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Key points
What is valerian?
What are common valerian preparations?
What are the historical uses of valerian?
What clinical studies have been done on valerian and sleep disorders?
How does valerian work?
What is the regulatory status of valerian in the United States?
Can valerian be harmful?
Who should not take valerian?
Does valerian interact with any drugs or affect laboratory tests?
What are some additional sources of scientific information on valerian?
Key points
This fact sheet provides an overview of the use of valerian for insomnia and other sleep disorders and contains the following key information:

What is valerian?
Valerian (Valeriana officinalis), a member of the Valerianaceae family, is a perennial plant native to Europe and Asia and naturalized in North America [1]. It has a distinctive odor that many find unpleasant [2,3]. Other names include setwall (English), Valerianae radix (Latin), Baldrianwurzel (German), and phu (Greek). The genus Valerian includes over 250 species, but V. officinalis is the species most often used in the United States and Europe and is the only species discussed in this fact sheet [3,4].
What are common valerian preparations?
Preparations of valerian marketed as dietary supplements are made from its roots, rhizomes (underground stems), and stolons (horizontal stems). Dried roots are prepared as teas or tinctures, and dried plant materials and extracts are put into capsules or incorporated into tablets [5].

There is no scientific agreement as to the active constituents of valerian, and its activity may result from interactions among multiple constituents rather than any one compound or class of compounds [6]. The content of volatile oils, including valerenic acids; the less volatile sesquiterpenes; or the valepotriates (esters of short-chain fatty acids) is sometimes used to standardize valerian extracts. As with most herbal preparations, many other compounds are also present.

Valerian is sometimes combined with other botanicals [5]. Because this fact sheet focuses on valerian as a single ingredient, only clinical studies evaluating valerian as a single agent are included.
What are the historical uses of valerian?
Valerian has been used as a medicinal herb since at least the time of ancient Greece and Rome. Its therapeutic uses were described by Hippocrates, and in the 2nd century, Galen prescribed valerian for insomnia [5,7]. In the 16th century, it was used to treat nervousness, trembling, headaches, and heart palpitations [8]. In the mid-19th century, valerian was considered a stimulant that caused some of the same complaints it is thought to treat and was generally held in low esteem as a medicinal herb [2]. During World War II, it was used in England to relieve the stress of air raids [9].

In addition to sleep disorders, valerian has been used for gastrointestinal spasms and distress, epileptic seizures, and attention deficit hyperactivity disorder. However, scientific evidence is not sufficient to support the use of valerian for these conditions [10].
What clinical studies have been done on valerian and sleep disorders?
In a systematic review of the scientific literature, nine randomized, placebo-controlled, double-blind clinical trials of valerian and sleep disorders were identified and evaluated for evidence of efficacy of valerian as a treatment for insomnia [11]. Reviewers rated the studies with a standard scoring system to quantify the likelihood of bias inherent in the study design [12]. Although all nine trials had flaws, three earned the highest rating (5 on a scale of 1 to 5) and are described below. Unlike the six lower-rated studies, these three studies described the randomization procedure and blinding method that were used and reported rates of participant withdrawal.

The first study used a repeated-measures design; 128 volunteers were given 400 mg of an aqueous extract of valerian, a commercial preparation containing 60 mg valerian and 30 mg hops, and a placebo [13]. Participants took each one of the three preparations three times in random order on nine nonconsecutive nights and filled out a questionnaire the morning after each treatment. Compared with the placebo, the valerian extract resulted in a statistically significant subjective improvement in time required to fall asleep (more or less difficult than usual), sleep quality (better or worse than usual), and number of nighttime awakenings (more or less than usual).This result was more pronounced in a subgroup of 61 participants who identified themselves as poor sleepers on a questionnaire administered at the beginning of the study. The commercial preparation did not produce a statistically significant improvement in these three measures. The clinical significance of the use of valerian for insomnia cannot be determined from the results of this study because having insomnia was not a requirement for participation. In addition, the study had a participant withdrawal rate of 22.9%, which may have influenced the results.

In the second study, eight volunteers with mild insomnia (usually had problems falling asleep) were evaluated for the effect of valerian on sleep latency (defined as the first 5-minute period without movement) [14]. Results were based on nighttime motion measured by activity meters worn on the wrist and on responses to questionnaires about sleep quality, latency, depth, and morning sleepiness filled out the morning after each treatment. The test samples were 450 or 900 mg of an aqueous valerian extract and a placebo. Each volunteer was randomly assigned to receive one test sample each night, Monday through Thursday, for 3 weeks for a total of 12 nights of evaluation. The 450-mg test sample of valerian extract reduced average sleep latency from about 16 to 9 minutes, which is similar to the activity of prescription benzodiazepine medication (used as a sedative or tranquilizer). No statistically significant shortening of sleep latency was seen with the 900-mg test sample. Evaluation of the questionnaires showed a statistically significant improvement in subjectively measured sleep. On a 9-point scale, participants rated sleep latency as 4.3 after the 450-mg test sample and 4.9 after the placebo. The 900-mg test sample increased the sleep improvement but participants noted an increase in sleepiness the next morning. Although statistically significant, this 7-minute reduction in sleep latency and the improvement in subjective sleep rating are probably not clinically significant. The small sample size makes it difficult to generalize the results to a broader population.

The third study examined longer-term effects in 121 participants with documented nonorganic insomnia [15]. Participants received either 600 mg of a standardized commercial preparation of dried valerian root (LI 156, Sedonium?*) or placebo for 28 days. Several assessment tools were used to evaluate the effectiveness and tolerance of the interventions, including questionnaires on therapeutic effect (given on days 14 and 28), change in sleep patterns (given on day 28), and changes in sleep quality and well-being (given on days 0, 14, and 28). After 28 days, the group receiving the valerian extract showed a decrease in insomnia symptoms on all the assessment tools compared with the placebo group. The differences in improvement between valerian and placebo increased between the assessments done on days 14 and 28.

(*The mention of a specific brand name is not an endorsement of the product.)

The reviewers concluded that these nine studies are not sufficient for determining the effectiveness of valerian to treat sleep disorders [11]. For example, none of the studies checked the success of the blinding, none calculated the sample size necessary for seeing a statistical effect, only one partially controlled prebedtime variables [15], and only one validated outcome measures [13].

Two other randomized, controlled trials published after the systematic review described above [11] are presented below.

In a randomized, double-blind study, 75 participants with documented nonorganic insomnia were randomly assigned to receive 600 mg of a standardized commercial valerian extract (LI 156) or 10 mg oxazepam (a benzodiazepine medication) for 28 days [16]. Assessment tools used to evaluate the effectiveness and tolerance of the interventions included validated sleep, mood scale, and anxiety questionnaires as well as sleep rating by a physician (on days 0, 14, and 28). Treatment result was determined via a 4-step rating scale at the end of the study (day 28). Both groups had the same improvement in sleep quality but the valerian group reported fewer side effects than did the oxazepam group. However, this study was designed to show superiority, if any, of valerian over oxazepam and its results cannot be used to show equivalence.

In a randomized, double-blind, placebo-controlled crossover study, researchers evaluated sleep parameters with polysomnographic techniques that monitored sleep stages, sleep latency, and total sleep time to objectively measure sleep quality and stages [17]. Questionnaires were used for subjective measurement of sleep parameters. Sixteen participants with medically documented nonorganic insomnia were randomly assigned to receive either a single dose and a 14-day administration of 600 mg of a standardized commercial preparation of valerian (LI 156) or placebo. Valerian had no effect on any of the 15 objective or subjective measurements except for a decrease in slow-wave sleep onset (13.5 minutes) compared with placebo (21.3 minutes). During slow-wave sleep, arousability, skeletal muscle tone, heart rate, blood pressure, and respiratory frequency decreased. Increased time spent in slow-wave sleep may decrease insomnia symptoms. However, because all but 1 of the 15 endpoints showed no difference between placebo and valerian, the possibility that the single endpoint showing a difference was the result of chance must be considered. The valerian group reported fewer adverse events than did the placebo group.

Although the results of some studies suggest that valerian may be useful for insomnia and other sleep disorders, results of other studies do not. Interpretation of these studies is complicated by the fact the studies had small sample sizes, used different amounts and sources of valerian, measured different outcomes, or did not consider potential bias resulting from high participant withdrawal rates. Overall, the evidence from these trials for the sleep-promoting effects of valerian is inconclusive.
How does valerian work?
Many chemical constituents of valerian have been identified, but it is not known which may be responsible for its sleep-promoting effects in animals and in in vitro studies. It is likely that there is no single active compound and that valerian's effects result from multiple constituents acting independently or synergistically [18,reviewed in 19].

Two categories of constituents have been proposed as the major source of valerian's sedative effects. The first category comprises the major constituents of its volatile oil including valerenic acid and its derivatives, which have demonstrated sedative properties in animal studies [6,20]. However, valerian extracts with very little of these components also have sedative properties, making it probable that other components are responsible for these effects or that multiple constituents contribute to them [21]. The second category comprises the iridoids, which include the valepotriates. Valepotriates and their derivatives are active as sedatives in vivo but are unstable and break down during storage or in an aqueous environment, making their activity difficult to assess [6,20,22].

A possible mechanism by which a valerian extract may cause sedation is by increasing the amount of gamma aminobutyric acid (GABA, an inhibitory neurotransmitter) available in the synaptic cleft. Results from an in vitro study using synaptosomes suggest that a valerian extract may cause GABA to be released from brain nerve endings and then block GABA from being taken back into nerve cells [23]. In addition, valerenic acid inhibits an enzyme that destroys GABA [reviewed in 24]. Valerian extracts contain GABA in quantities sufficient to cause a sedative effect, but whether GABA can cross the blood-brain barrier to contribute to valerian's sedative effects is not known. Glutamine is present in aqueous but not in alcohol extracts and may cross the blood-brain barrier and be converted to GABA [25]. Levels of these constituents vary significantly among plants depending on when the plants are harvested, resulting in marked variability in the amounts found in valerian preparations [26].
What is the regulatory status of valerian in the United States?
In the United States, valerian is sold as a dietary supplement, and dietary supplements are regulated as foods, not drugs. Therefore, premarket evaluation and approval by the Food and Drug Administration are not required unless claims are made for specific disease prevention or treatment. Because dietary supplements are not always tested for manufacturing consistency, the composition may vary considerably between manufacturing lots.
Can valerian be harmful?
Few adverse events attributable to valerian have been reported for clinical study participants. Headaches, dizziness, pruritus, and gastrointestinal disturbances are the most common effects reported in clinical trials but similar effects were also reported for the placebo [14-17]. In one study an increase in sleepiness was noted the morning after 900 mg of valerian was taken [14]. Investigators from another study concluded that 600 mg of valerian (LI 156) did not have a clinically significant effect on reaction time, alertness, and concentration the morning after ingestion [27]. Several case reports described adverse effects, but in one case where suicide was attempted with a massive overdose it is not possible to clearly attribute the symptoms to valerian [28-31].

Valepotriates, which are a component of valerian but are not necessarily present in commercial preparations, had cytotoxic activity in vitro but were not carcinogenic in animal studies [32-35].
Who should not take valerian?

  • Women who are pregnant or nursing should not take valerian without medical advice because the possible risks to the fetus or infant have not been evaluated [36].
  • Children younger than 3 years old should not take valerian because the possible risks to children of this age have not been evaluated [36].
  • Individuals taking valerian should be aware of the theoretical possibility of additive sedative effects from alcohol or sedative drugs, such as barbiturates and benzodiazepines [10,37,38].

Does valerian interact with any drugs or affect laboratory tests?
Although valerian has not been reported to interact with any drugs or to influence laboratory tests, this has not been rigorously studied [5,10,36].
What are some additional sources of scientific information on valerian?
Medical libraries are a source of information about medicinal herbs. Other sources include Web-based resources such as PubMed available at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?holding=nih.

For general information on botanicals and their use as dietary supplements, please see Background Information About Botanical Dietary Supplements (http://ods.od.nih.gov/factsheets/botanicalbackground.asp) and General Background Information About Dietary Supplements (http://ods.od.nih.gov/factsheets/dietarysupplements.asp), from the Office of Dietary Supplements (ODS).



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administration - The process of giving a person a medicine or dietary supplement by mouth, by vein, on the skin, or by another route. For example, a 14-day administration of valerian extract.
adverse effect - An unwanted side effect.
adverse event - An unwanted medical problem that occurs during treatment. Adverse events may be unrelated to the treatment or they may be caused by the therapy or procedure. For example, an adverse event may be caused by the toxic effects of a particular drug or dietary supplement or by an interaction with another therapy. Also called adverse effect and side effect.
animal study - A laboratory test using animals to study the development and course of human diseases, and to test the safety and effectiveness of new treatments before they are given to humans.
aqueous - Having to do with water.
attention deficit hyperactivity disorder - ADHD. A common mental disorder that usually develops before age 7 and may continue into adulthood. Symptoms include inattention, excessive impulsiveness, and/or inability to remain still and quiet.
barbiturate - A category of drug used to treat seizure disorders, insomnia, and anxiety and to calm patients before surgery. It belongs to the family of drugs called central nervous system depressants.
benzodiazepine - A category of drug used to treat seizure disorders, insomnia, anxiety, alcohol withdrawal, and muscle spasms, and to calm patients before surgery. It belongs to the family of drugs called central nervous system depressants.
bias - In a clinical trial, the result of a flaw in the study design or method of collecting or interpreting the study information that can lead to incorrect conclusions.
blinding - A process used in clinical trials to assign individuals to the control group (to receive the standard treatment) or the test group (to receive the new treatment under study) without the individuals or the researchers knowing to which group they have been assigned. Blinding helps ensure that information collected in the study is true and not biased (flawed). In a single-blinded study, the individuals do not know whether the standard treatment or a new treatment is being given. In a double-blinded study, neither the individuals nor the researchers know which treatment is being given.
blood-brain barrier - A network of specialized cells that prevents certain substances, including many toxins and potentially harmful substances, from leaving the blood vessels and entering the brain.
botanical - Having to do with plants or plant parts, or dietary supplement products made from plants.
capsule - A gelatin shell containing a dose of medicine, a vitamin, or other dietary supplement.
carotenoid - A substance that makes certain fruits and vegetables yellow, orange, or red. Some carotenoids (beta-carotene, alpha-carotene, and beta-cryptoxanthin) can be made into vitamin A by the body. Other carotenoids (lycopene, lutein, and zeaxanthin) cannot be made into vitamin A by the body. All carotenoids are antioxidants.
case report - A detailed record of the diagnosis, treatment, and follow-up of an individual patient. Case reports also contain some information about the patient (such as age, gender, and ethnic origin).
clinical significance - In medicine, a judgment that a change caused by a treatment or dietary supplement has practical importance for a patient's health. Clinical significance is different from statistical significance, which focuses on making a mathematical determination about whether the change might or might not be expected to happen by chance.
Example: Suppose the results of a clinical trial show that people with sleep disorders who took a particular supplement slept 10 minutes longer each night than people who took a placebo and the difference of 10 minutes was statistically significant. Also, the results of earlier research show that sleeping at least 60 minutes longer each night would help a person with a sleep disorder feel well rested when they wake up. The results of this study would not be judged as clinically significant because the people who took the supplement only slept an additional 10 minutes and not the 60 minutes experts have determined can help a person with a sleep disorder feel well rested when they wake up. But the study results would still be considered statistically significant.
clinical trial - A type of research study that uses volunteers to test the safety and efficacy (the ability to produce a beneficial effect) of new methods of screening (checking for disease when there are no symptoms), prevention, diagnosis, or treatment of a disease. Also called a clinical study.
commercial preparation - A product such as a drug or dietary supplement made in large quantities to be sold.
compound - In pharmacy, a substance that contains more than one ingredient.
constituent - A component, part, or ingredient of a larger whole. For example, valerenic acid and valepotriate are constituents of the dietary supplement valerian.
cytotoxic - Cell-killing.
day 0 - Sometimes used to indicate the first day of treatment.
derivative - In chemistry, a compound made from or related to another compound.
dietary supplement - A product that is intended to supplement the diet. A dietary supplement contains one or more dietary ingredients (including vitamins, minerals, herbs or other botanicals, amino acids, and other substances) or their components; is intended to be taken by mouth as a pill, capsule, tablet, or liquid; and is identified on the front label of the product as being a dietary supplement.
distress - Mental or physical pain or suffering.
double-blind - Describes a clinical trial in which neither the researcher nor the patient knows which of several possible therapies the patient is receiving.
effectiveness - In medicine, the ability of an intervention (for example, a drug, surgery, or a dietary supplement) to produce the desired beneficial effect under the usual conditions of care by a health care provider.
efficacy - In medicine, the ability of an intervention (for example, a drug, surgery, or dietary supplement) to produce the desired beneficial effect under the best possible conditions of care, such as a clinical trial.
endpoint - A specific outcome measured in a clinical trial that is used to judge how well the treatment works (treatment efficacy). For example, the endpoint measured in a clinical trial may be weight loss, quality of life, or survival.
enzyme - A protein that speeds up chemical reactions in the body.
esteem - Admiration, regard, respect, and value.
ester - A chemical compound made by the reaction between an alcohol and an acid.
evidence - Information used to support the use of a particular screening procedure, treatment, or preventive measure. In medicine, evidence needed to determine effectiveness is provided by laboratory research, clinical trials, and other studies.
extract - A substance made by soaking an herb in a liquid that removes specific types of chemicals. The liquid can be used as is or evaporated to make a concentrate or a dry extract for use in capsules or tablets.
fetus - The developing human from 7 to 8 weeks after conception until birth.
gamma aminobutyric acid - GABA. A chemical found naturally in plants and animals. It stops nerve cells from communicating with each other and decreases electrical activity and nerve impulses in the brain. At high levels, GABA may cause a lack of coordination, sedation, and anesthesia.
gastrointestinal - GI. Having to do with the gastrointestinal tract (the large, muscular tube that extends from the mouth to the anus, where the movement of muscles and release of hormones and enzymes digest food).
genus - The name of a category that is part of the scientific classification of all organisms. Genus is located in the classification system after kingdom, phylum, class, order, and family and before the subclassification of species. Humans, for example, belong to the genus Homo and are identified by the scientific name Homo (genus) sapiens (species).
glutamine - A chemical that increases the number of messages sent between nerve cells. It is thought to be involved in learning and memory.
H2 receptor antagonist - A medication that reduces the amount of acid made by the stomach. It is used to treat conditions such as stomach ulcer (peptic ulcer) and gastroesophageal reflux disease.
heart palpitation - Forceful and irregular beating of the heart.
herb - A plant used in cooking, in tea, and for medicinal purposes.
herbal - Having to do with or made from medicinal or edible plants.
in vitro - In the laboratory (outside the body).
in vivo - In the body.
infant - A child younger than 12 months old.
ingestion - Taking into the body by mouth.
inhibitory neurotransmitter - A chemical that stops one nerve cell (neuron) from communicating with the next nerve cell, and decreases or blocks the transmission of nerve impulses. The main inhibitory neurotransmitter in the brain is gamma aminobutyric acid (GABA). See: excitatory neurotransmitter.
insomnia - Difficulty in going to sleep or in getting enough sleep.
interaction - In pharmacy, the effect that results from combining two or more drugs or dietary supplements that neither drug nor dietary supplement produces when taken individually. Such interactions can increase or decrease the absorption, metabolism, effectiveness, and safety of a drug or dietary supplement.
iridoid - A category of compounds found in some plants.
laboratory test - A medical procedure that involves testing a sample of blood, urine, tissue, or other substance collected from the body. Tests can help determine a diagnosis, plan treatment, check to see whether treatment is working, or monitor a disease over time.
lot - A batch, or a specific identified portion of a batch, having uniform character and quality within specified limits; or, an amount produced in a unit of time or quantity.
mechanism of action - The means by which a substance (such as a dietary supplement) is able to produce an effect in the body.
medicinal - Having to do with the abilities of medicine to prevent and cure.
milligram - mg. A measure of weight. It is a metric unit of mass equal to 0.001 gram (it weighs 28,000 times less than an ounce).
naturalize - To introduce a plant from one geographic region to another, and to allow it to establish itself without cultivation, and grow as if it were native to the area.
nerve ending - The end of a nerve fiber that projects from the cell body of a nerve cell (neuron).
nonorganic insomnia - A sleep disorder (difficulty in going to sleep or getting enough sleep) that occurs as a symptom of a physical or mental disease.
nursing - Breastfeeding.
objective - Having to do with fact, experience, or direct observation rather than personal opinion or feeling.
outcome - A specific endpoint measured in a clinical trial. Examples include weight loss, cholesterol levels, severe toxicity, worsening of disease, and death.
oxazepam - A drug used to treat anxiety, sleeping disorders, irritable bowel syndrome, and the symptoms of alcohol withdrawal. It belongs to the family of drugs called benzodiazepines.
participant withdrawal - When a person enrolled as a subject in a clinical trial stops participating before the study is completed.
placebo - An inactive substance or treatment that has no effect on the body and that ideally looks, smells, and tastes the same as, and is given the same way as, the active drug or treatment being tested. The effects of the active substance or treatment are compared to the effects of the placebo.
placebo-controlled - Refers to a method of studying a drug or dietary supplement in which a placebo (an inactive ingredient) is given to one group of participants, and the drug or dietary supplement being tested is given to a second group of participants. Results from the two groups are compared to see if the drug or dietary supplement being tested works better than the placebo.
polysomnography - PSG. The use of an instrument (called a polysomnograph) that is used to measure the quality of sleep and identify sleep disorders. PSG records measurements of brain activity, eye movement, and muscle tension in the face, and may include the measurement of heart rate, breathing rate, leg movements, blood pressure, and body temperature.
population - All individuals who share something in common (such as geographic location, ethnicity, gender, age, or disease). In statistics, conclusions are made about the population by studying smaller sample groups of individuals who are representative of the larger group.
preparation - A mixture made for medicinal use.
prescription - A written order from a health care provider for medicine, other therapy, or tests.
prevention - In medicine, action taken to decrease the chance (risk) of developing a disease.
pruritus - An itching sensation that triggers the desire to scratch. Pruritus can range from mild to severe.
randomization - When referring to an experiment or clinical trial, the process by which animal or human subjects are assigned by chance to separate groups that compare different treatments or other therapies. Randomization gives each participant an equal chance of being assigned to any of the groups.
regulate - To govern, make uniform, and bring under the control of a rule, principle, or legal system. In the United States, the FDA has the authority to regulate dietary supplements.
respiratory - Having to do with breathing. The organs that are involved with breathing include the mouth, nose, throat (pharynx), voicebox (larynx), windpipe (trachea), air passages between the windpipe and lungs (bronchial tubes), and lungs.
rhizome - A horizontal stem that grows shallowly underground. At nodes along the rhizome, below-ground roots and above-ground shoots grow into new plants. Examples include strawberries and many types of grasses.
rigorous - Accurate, precise, and without deviation from standards.
risk - The chance or probability that a harmful event will occur.
sample - A subset of individuals selected from a larger population. A sample is used to form conclusions about the general population.
scientific literature - Published peer-reviewed original research in the sciences and social sciences.
sedative - A drug or other substance that helps cause relaxation, calmness, and sleepiness.
sesquiterpene - A substance found in some plants.
short-chain fatty acid - A fat molecule that is composed of 6 or fewer carbon atoms. This type of fat is able to dissolve in water and is digested and absorbed more rapidly than other fats.
sleep disorder - A consistent disruption of the normal pattern of sleep.
sleep latency - The period of time between settling down to go to sleep and actually falling asleep.
slow-wave sleep - Deep, nondreaming sleep.
spasm - An abnormal and uncontrollable muscle contraction or cramp.
species - The name of a category that is part of the scientific classification of all organisms. The category species is located in the classification system after kingdom, phylum, class, order, family and genus. Humans, for example, belong to the species sapiens and are identified by the scientific name Homo (genus) sapiens (species).
standardization - A process manufacturers may use to ensure batch-to-batch consistency of their products and to provide a measure of quality control. Dietary supplements are not required to be standardized in the United States. Some manufacturers use the term incorrectly or to mean different things and the presence of the word "standardized" on a supplement label does not necessarily indicate a level of product quality.
statistical effect - Describes a mathematical measure of difference between groups.
statistically significant - In medicine, a mathematical measure of difference between two or more groups receiving different treatments that is greater than what might be expected to happen by chance alone.
stimulant - A substance that increases brain activity, alertness, attention, blood pressure, heart rate, breathing, and energy.
stolon - A specialized stem that grows horizontally on top of the ground; roots and new plants form at nodes along the stolon. An example is the strawberry plant.
subjective - Influenced by experience, knowledge, opinion, or emotion; not based on facts alone.
subjective improvement - An improvement that is reported by a person but cannot be measured by a healthcare provider. For example, "I feel better."
subjective measurement - A method of determining an effect when precise numbers cannot be known. Examples of tools used in subjective measurement include questionnaires and sliding scales. For example, "On a scale of 1 to 10, my pain is an 8."
symptom - An indication of disease that an individual can feel, but that cannot be measured objectively by a health care professional. Examples include headache, fatigue, indigestion, depression, and pain.
synaptic cleft - The gap between nerve cells (neurons). Nerve cells communicate with each other by sending and receiving chemical messages (neurotransmitters) across the synaptic cleft.
synaptosome - A sac of nerve-ending particles that have been processed in a centrifuge in the laboratory. Synaptosomes are used in lab tests to study communication between nerve cells (neurons).
synergism - The interaction of two or more substances to produce an effect that is greater than what would be expected by adding the separate effects of each.
systematic review - A structured method of identifying, selecting, and analyzing appropriate research to answer a specific question.
tea - A drink made by adding boiling water to fresh or dried herbs and steeping (soaking) them. It may be drunk either hot or cold. Also called an infusion.
theoretical - Describes an assumption that is supported by scientific evidence, but has not been proven.
therapeutic - Used to treat disease and help healing take place.
therapeutic effect - The beneficial response or outcome of a treatment or prevention measure.
tincture - A liquid made by soaking an herb in a solution of alcohol and water. It is used for concentrating and preserving an herb and may be made in different strengths that are expressed as ratios of the weight of the dried herb to the volume or weight of the finished product.
tolerance - The ability to take a drug or dietary supplement without discomfort or unwanted side effects. Also, a condition that occurs when the body gets used to a drug or dietary supplement so that either larger amounts or a different drug or supplement is needed to get the same effect originally experienced.
tranquilizer - A drug used to treat anxiety and insomnia. It belongs to the family of drugs called central nervous system (CNS) depressants. An example is valium.
treat - To care for a patient with a disease by using medicine, surgery, or other approaches.
valepotriate - An active component of valerian. It has a sedative effect.
valerenic acid - An active component of valerian. It is has a sedative effect.
valerian - The roots of this plant are used by some cultures as an ingredient in mild sedatives and sleep aids for nervous tension and insomnia. It is being studied in improving sleep in patients undergoing treatment for cancer. Latin name: Valeriana officinalis.
validate - A process of distinct steps providing documented evidence that an analytic method does what it is intended to do. Validation applies to a defined protocol, for the determination of a specified analyte (the substance being analyzed) and range of concentrations in a specified type of test material (matrix) with a high degree of accuracy and precision, used for a specified purpose.
volatile - Describes a substance that evaporates quickly.
volatile oil - An oil that vaporizes easily and is responsible for the fragrance of some plants.
well-being - The state of feeling healthy, happy, and content. Well-being is affected by things such as physical and mental health, income, education, social support, attitude, values, stress, security, and other qualities of life.

The mention of a specific brand name is not an endorsement of the product. Reasonable care has been taken in preparing this fact sheet and the information provided herein is believed to be accurate. However, this information is not intended to constitute an "authoritative statement" under Food and Drug Administration rules and regulations.

About ODS
The mission of the Office of Dietary Supplements (ODS) is to strengthen knowledge and understanding of dietary supplements by evaluating scientific information, stimulating and supporting research, disseminating research results, and educating the public to foster an enhanced quality of life and health for the U.S. population.

General Safety Advisory

  • The information in this document does not replace medical advice.
  • Before taking an herb or a botanical, consult a doctor or other health care provider-especially if you have a disease or medical condition,take any medications, are pregnant or nursing, or are planning to have an operation.
  • Before treating a child with an herb or a botanical, consult with a doctor or other health care provider.
  • Like drugs, herbal or botanical preparations have chemical and biological activity. They may have side effects. They may interact with certain medications. These interactions can cause problems and can even be dangerous.
  • If you have any unexpected reactions to an herbal or a botanical preparation, inform your doctor or other health care provider.

Information Provided By:
Office of Dietary Supplements
National Institutes of Health
Bethesda, Maryland 20892 USA
Web: http://ods.od.nih.gov
E-mail: ods@nih.gov