Kava

Several well-conducted human studies have demonstrated kava's efficacy in the treatment of anxiety, with effects observed after as few as one to two doses, and progressive improvements over one to four weeks. Preliminary evidence suggests possible equivalence to benzodiazepines.

Many experts believe that kava is neither sedating nor tolerance-forming in recommended doses. Some trials report occasional mild sedation, although preliminary data from small studies suggest lack of neurological-psychological impairment.

There is growing concern regarding the potential for liver toxicity from kava. Multiple cases of liver damage have been reported in Europe, including hepatitis, cirrhosis, and liver failure. Kava has been removed from shelves in several countries due to these safety concerns. The United States Food and Drug Administration (FDA) has issued warnings to consumers and physicians. It is not clear what dose or duration of use is correlated with the risk of liver damage. The quality of these case reports has been variable; several are vague, describe use of products that do not actually list kava as an ingredient, or include patients who also ingest large quantities of alcohol. Nonetheless, caution is warranted.

Chronic or heavy use of kava has also been associated with cases of neurotoxicity, pulmonary hypertension, and dermatologic changes. Most human trials have been shorter than two months, with the longest study being six months in duration.

Synonyms

(+) -dihydrokawain-5-ol, 11-methoxy-5, 5-hydroxydihydrokawain, 6-dihydroyangonin, Antares, ava pepper, ava pepper shrub, ava root, awa, bornyl cinnamate, cavain, flavokavines A and B, gea, gi, intoxicating long pepper, intoxicating pepper, kao, kavakava, kava kava extract LI 140, kava kava rhizome, kavapiper, kavarod, kava root, kavasporal forte, kavain, kave-kave, kawa, kawa kawa, kawa pepper, Kawa Pfeffer, kew, Macropiper latifolium, malohu, maluk, maori kava, meruk, milik, pepe kava, Piper methysticum, pipermethystine, piperis methystici rhizoma, Rauschpfeffer, rhizoma piperis methystici, sakau, sakua, tonga, yagona, yangona, yaqona.

Evidence

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Uses based on scientific evidence	Grade^*
Anxiety Human studies have found at least moderate benefit of kava in the treatment of anxiety, and preliminary evidence suggests that kava may be equivalent to benzodiazepine drugs such as diazepam (Valium®). Kava's effects were reported to be similar to the prescription drug buspirone (Buspar®) used for Generalized Anxiety Disorder (GAD) in one study. However, there is concern regarding kava's potential toxicity, based on multiple reports of liver damage in Europe and a number of cases in the U.S., including hepatitis, cirrhosis, and liver failure. The US FDA has issued warnings to consumers and physicians. Many products have been pulled from the market. Natural Standard has collaborated with the World Health Organization (WHO) to prepare a detailed report of kava and associated adverse effects, which will be published soon.	A
Stress Early study results suggest that kava and valerian may be beneficial to health by reducing physiological reactivity during stressful situations and stress induced insomnia. Further research is needed to confirm these results.	C
Parkinson's disease Kava has been shown to increase 'off' periods in Parkinson patients taking levodopa and can cause a semicomatose state when given with alprazolam. Therefore, it is not recommended.	D

*Key to grades
A: Strong scientific evidence for this use;
B: Good scientific evidence for this use;
C: Unclear scientific evidence for this use;
D: Fair scientific evidence against this use;
F: Strong scientific evidence against this use.

Grading rationale

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Anesthesia, anorexia, anticraving agent (addiction), antifungal, antipsychotic, aphrodisiac, arthritis, asthma, birth control, brain damage, bust enhancement, cancer, colds, cystitis, depression, diuretic, dizziness, gonorrhea, hemorrhoids, infections, jet lag, joint pain and stiffness, kidney disorders, leprosy, menopause, menstrual disorders, migraine headache, neuroprotective, pain, premenstrual syndrome (PMS), premenstrual dysphoric disorder (PMDD), protection of brain tissue against ischemic damage, seizures, spasm, stomach upset, syphilis, toothache, tuberculosis, urinary tract disorders, uterus inflammation, vaginal prolapse, vaginitis, weight reduction, wound healing.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older)

300 milligrams of kava extract daily (standardized WS 1490 preparation) taken by mouth in three divided doses has been found beneficial in human studies for anxiety. Typical doses range from 50 to 280 milligrams of kava lactones daily, as a single bedtime dose or in divided doses, using a lower dose first and increasing slowly if necessary. Doses as high as 800 milligrams daily of kava extract have been taken for short periods, but have not been studied over the long term, and safety is not clear.

Children (younger than 18 years)

There is not enough scientific evidence to recommend the use of kava in children.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergic skin rashes have occasionally been reported.

Side Effects and Warnings

Until recently, kava was generally thought to be safe when used in otherwise healthy people not on any other drugs, herbs or supplements, over short periods of time (one to two months) at recommended doses. Side effects may include gastrointestinal (stomach) upset, allergic rash, or mild headache. There have been numerous reports of severe liver problems in people using kava. Multiple cases of liver toxicity, including liver failure, have been reported following use of kava in Europe. The U.S. FDA has issued warnings to consumers and physicians, and has requested that physicians report cases of liver toxicity that may be related to kava use. Although many natural medicine experts still believe that kava is safe at recommended doses, there is not enough scientific information to make a clear conclusion. Therefore, kava should be used only under the supervision of a qualified healthcare professional, should never be used above recommended doses, and should be avoided by people with liver problems or taking drugs that affect the liver.

Other serious side effects have been observed with chronic or heavy use of kava, including skin disorders, blood abnormalities, abnormal muscle movements, apathy, kidney damage, seizures, psychotic syndromes, and increased blood pressure in the lungs (pulmonary hypertension). Blood in the urine has also been reported.

Several cases of abnormal muscle movements have been reported after short-term use of kava (one to four days), including tightening, twisting, or locking of the muscles of the mouth, neck (torticollis) and eyes (oculogyric crisis). Worsening of symptoms of Parkinson's disease, and several cases of abnormal whole body movements (choreoathetosis) following high doses of kava have also been noted. Tremor, poor coordination, headache, drowsiness, and fatigue have uncommonly been reported, particularly with large doses. A case of muscle cell breakdown (rhabdomyolysis) was reported in a 29 year-old man after taking an herbal combination of ginkgo, guarana, and kava.

Sedation (drowsiness) has occasionally been reported with kava use, although there is early evidence from several small human studies that kava may not significantly cause this effect. Because this issue remains unclear, driving and operating heavy machinery is not recommend while taking kava.

Eye disturbances and eye irritation have rarely been associated with chronic or heavy kava use. Rapid heart rate, electrocardiogram (ECG) abnormalities, and shortness of breath have been reported in heavy kava users. Laboratory tests suggest that kava may increase the risk of bleeding through effects on blood platelets.

Kava may cause sedation and affect electroconvulsive therapy (ECT) outcome. It has also been associated with meningismus, urinary retention, skin lesions, mood elevation, enhanced or decreased cognitive performance, anorexia, sleeplessness, palpitations, paresthesia, headache, vomiting, and dangerously high blood pressure.

Pregnancy & Breastfeeding

Use of kava cannot be recommended during pregnancy or breastfeeding. There may be decreases in the muscle strength of the uterus with the use of kava, which may have harmful effects on pregnancy. Chemicals in kava may pass into breast milk with unknown effects, and therefore this herb should be avoided during breastfeeding.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

Interactions with Drugs

Based on multiple human reports of liver toxicity, including hepatitis, cirrhosis, and liver failure, a theoretical increased risk of liver damage may occur if kava is taken with drugs that may injure the liver such as alcohol or acetaminophen (Tylenol®).

In theory, kava may increase the effects of alcohol or other drugs that cause sedation (drowsiness). In theory, kava may interfere with the effects of dopamine or drugs that are similar to dopamine, and may worsen the neurologic side effects of drugs that block dopamine such as haloperidol (Haldol®).

Kava may have chemical properties similar to monoamine oxidase inhibitors (MAO-I). In theory, kava may add to the effects of MAO-I antidepressants, such as isocarboxazid (Marplan®), phenelzine (Nardil®), or tranylcypromine (Parnate®). Due to this possible effect, kava may also cause the effects of anesthesia to last longer, and some practitioners recommend stopping kava two to three days before surgery.

Laboratory tests suggest that kava may increase the risk of bleeding through effects on blood platelets. However, human evidence is lacking in this area. People using aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) and heparin, or anti-platelet drugs such as clopidogrel (Plavix®) should be aware of possible interactions .

Since kava has diuretic properties, it may have additive effects when taken with diuretic drugs such as furosemide or with ACE inhibitors such as benazepril or captopril. Avoid in Parkinson's disease or in patients with a history of medication-induced extrapyramidal effects because kava may cause additive effects. Kava may cause excessive drowsiness when taken with SSRI antidepressant drugs such as fluoxetine or sertraline. Buspirone and opipramol may have additive effects when taken with kava.

Preliminary evidence shows that kava may interfere with the way the body processes certain drugs using the liver's "cytochrome P450" enzyme system. As a result, the levels of these drugs may be altered in the blood, and may cause different effects or potentially serious adverse reactions.

Interactions with Herbs & Dietary Supplements

In theory, kava may increase the sedation (drowsiness) caused by some herbs and supplements.

Kava may have chemical properties similar to antidepressant drugs monoamine oxidase inhibitors (MAO-I) and therefore may interact with herbs and supplements with similar effects.

Based on laboratory tests, it is suggested that kava may increase the risk of bleeding through effects on blood platelets. However, human evidence is lacking in this area. People using other herbs or supplements that may increase the risk of bleeding should speak with a healthcare professional before starting kava.

Nausea, sweating, muscle cramping, weakness and increased pulse and blood pressure has been reported after a single dose of combination St. John's wort, kava, and valerian.

Since kava has diuretic properties, it may have additive effects when taken with diuretic herbs or supplements like horsetail or licorice.

Preliminary evidence shows that kava may interfere with the way the body processes certain herbs or supplements using the liver's "cytochrome P450" enzyme system. As a result, the levels of other herbs or supplements to be too high in the blood.

Kava (Piper methysticum G. Forst)

Background

Synonyms

Evidence

Dosing

Safety

Interactions