URL of this page: https://www.nlm.nih.gov/medlineplus/druginfo/natural/872.html


What is it?

Kava is a plant native to the South Pacific. The root is used for medicine.

There are some BIG safety concerns about kava. Many cases of liver damage and even some deaths have been traced to kava use. As a result, kava has been banned from the market in Switzerland, Germany, and Canada, and several other countries are considering similar action. This ban has hurt the economies of Pacific Island countries that export kava.

Kava is used to calm anxiety, stress, and restlessness, and treat sleep problems (insomnia). It is also used for attention deficit-hyperactivity disorder (ADHD), epilepsy, psychosis, depression, migraines and other headaches, chronic fatigue syndrome (CFS), common cold and other respiratory tract infections, tuberculosis, muscle pain, and cancer prevention.

Some people use kava for urinary tract infections (UTIs), pain and swelling of the uterus, venereal disease, menstrual discomfort, and to arouse sexual desire.

Kava is applied to the skin for skin diseases including leprosy, to promote wound healing, and as a painkiller. It is also used as a mouthwash for canker sores and toothaches.

Kava was named by the explorer Captain Cook, who chose a name that meant "intoxicating pepper." While Captain Cook may have named kava, he didn’t discover it. Kava has been used for thousands of years by Pacific Islanders. Today in the South Pacific, kava is a popular social drink, similar to alcohol in Western societies. It also still has a role in rituals and ceremonies.

How effective is it?

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.

The effectiveness ratings for KAVA are as follows:

Possibly effective for...

  • Anxiety. The majority of evidence shows that certain kava extracts (extracts standardized to 70% kavalactones) can lower anxiety and might work as well as prescription anti-anxiety medications called low-dose benzodiazepines. But it might take up to 8 weeks of treatment to see improvement.

Insufficient evidence to rate effectiveness for...

  • Benzodiazepine withdrawal symptoms. Some research suggests that slowly increasing the dose of kava while decreasing the dose of benzodiazepines over the course of a week can prevent withdrawal symptoms and reduce anxiety in people who have been taking benzodiazepines for a long period of time.
  • Cancer prevention. There is some evidence that taking kava might help to prevent cancer.
  • Insomnia. Research on the effectiveness of kava in people with sleeping problems is unclear. Evidence shows that taking 200 mg of a kava extract (WS1490) daily for 4 weeks reduces sleeping problems associated with anxiety. However, a study using a different kava product found that it did not reduce sleeping problems associated with anxiety.
  • Anxiety related to menopause. Early research shows that taking 300 mg of a kava extract product (WS1490) daily for 8 weeks reduces anxiety and hot flashes in women with menopause.
  • Stress. Early research suggests that taking a single dose of kava by mouth might reduce the physical changes associated with mentally stressful tasks.
  • Restlessness.
  • Attention deficit-hyperactivity disorder (ADHD).
  • Epilepsy.
  • Psychosis.
  • Depression.
  • Chronic fatigue syndrome (CFS).
  • Headaches.
  • Colds.
  • Respiratory tract infections.
  • Tuberculosis.
  • Achy joints (rheumatism).
  • Chronic bladder infections.
  • Sexually transmitted diseases.
  • Menstrual problems.
  • Other conditions.
More evidence is needed to rate kava for these uses.

How does it work?

Kava affects the brain and other parts of the central nervous system. The kava-lactones in kava are believed to be responsible for its effects.

Are there safety concerns?

Kava is POSSIBLY UNSAFE when taken by mouth. Don’t use it. Serious illness, including liver damage, has occurred even with short-term use of normal doses. The use of kava for as little as one to three months has resulted in the need for liver transplants, and even death. Early symptoms of liver damage include yellowed eyes and skin (jaundice), fatigue, and dark urine. If you decide to take kava, despite warnings to the contrary, be sure to get frequent liver function tests.

Using kava can make you unable to drive or operate machinery safely. Do not take kava before you plan on driving. "Driving-under-the-influence" citations have been issued to people driving erratically after drinking large amounts of kava tea.

Special precautions & warnings:

Pregnancy and breast-feeding: Don’t use kava if you are pregnant or breast-feeding. Kava is POSSIBLY UNSAFE when taken by mouth. There is a concern that it might affect the uterus. Also, some of the dangerous chemicals in kava can pass into breast milk and might hurt a breast-fed infant.

Depression: Kava use might make depression worse.

Liver problems: Kava is hard on the liver, even healthy ones. Taking kava if you already have liver disease is taking a risk.

Surgery: Kava affects the central nervous system. It might increase the effects of anesthesia and other medications used during and after surgery. Stop using kava at least 2 weeks before a scheduled surgery.

Are there interactions with medications?

Do not take this combination.
Sedative medications (CNS depressants)
Kava might cause sleepiness and drowsiness. Medications that cause sleepiness are called sedatives. Taking kava along with sedative medications might cause too much sleepiness.

Some sedative medications include clonazepam (Klonopin), lorazepam (Ativan), phenobarbital (Donnatal), zolpidem (Ambien), and others.
Be cautious with this combination.
Alprazolam (Xanax)
Kava can cause drowsiness. Alprazolam (Xanax) can also cause drowsiness. Taking kava along with alprazolam (Xanax) may cause too much drowsiness. Avoid taking kava and alprazolam (Xanax) together.
Levodopa affects the brain by increasing a brain chemical called dopamine. Kava might decrease dopamine in the brain. Taking kava along with levodopa might decrease the effectiveness of levodopa.
Medications changed by the liver (Cytochrome P450 1A2 (CYP1A2) substrates)
Some medications are changed and broken down by the liver. Kava might decrease how quickly the liver breaks down some medications. Taking kava along with some medications that are changed by the liver might increase the effects and side effects of some medications. Before taking kava, talk to your healthcare provider if you take any medications that are changed by the liver.

Some of these medications that are changed by the liver include clozapine (Clozaril), cyclobenzaprine (Flexeril), fluvoxamine (Luvox), haloperidol (Haldol), imipramine (Tofranil), mexiletine (Mexitil), olanzapine (Zyprexa), pentazocine (Talwin), propranolol (Inderal), tacrine (Cognex), theophylline, zileuton (Zyflo), zolmitriptan (Zomig), and others.
Medications changed by the liver (Cytochrome P450 2C19 (CYP2C19) substrates)
Some medications are changed and broken down by the liver. Kava might decrease how quickly the liver breaks down some medications. Taking kava along with some medications that are broken down by the liver can increase the effects and side effects of your medication. Before taking kava, talk to your healthcare provider if you take any medications that are changed by the liver.

Some of these medications changed by the liver include amitriptyline (Elavil), clomipramine (Anafranil), cyclophosphamide (Cytoxan), diazepam (Valium), lansoprazole (Prevacid), omeprazole (Prilosec), lansoprazole (Protonix), phenytoin (Dilantin), phenobarbital (Luminal), progesterone, and others.
Medications changed by the liver (Cytochrome P450 2C9 (CYP2C9) substrates)
Some medications are changed and broken down by the liver. Kava might decrease how quickly the liver breaks down some medications. Taking kava along with some medications that are broken down by the liver can increase the effects and side effects of some medications. Before taking kava, talk to your healthcare provider if you take any medications that are changed by the liver.

Some medications that are changed by the liver include amitriptyline (Elavil), diazepam (Valium), zileuton (Zyflo), celecoxib (Celebrex), diclofenac (Voltaren), fluvastatin (Lescol), glipizide (Glucotrol), ibuprofen (Advil, Motrin), irbesartan (Avapro), losartan (Cozaar), phenytoin (Dilantin), piroxicam (Feldene), tamoxifen (Nolvadex), tolbutamide (Tolinase), torsemide (Demadex), warfarin (Coumadin), and others.
Medications changed by the liver (Cytochrome P450 2E1 (CYP2E1) substrates)
Some medications are changed and broken down by the liver. Kava might decrease how quickly the liver breaks down some medications. Taking kava along with some medications that are changed by the liver can increase the effects and side effects of your medication. Before taking kava, talk to your healthcare provider if you take any medications that are changed by the liver.

Some medications that are changed by the liver include acetaminophen, chlorzoxazone (Parafon Forte), ethanol, theophylline, and drugs used for anesthesia during surgery such as enflurane (Ethrane), halothane (Fluothane), isoflurane (Forane), and methoxyflurane (Penthrane).
Medications changed by the liver (Cytochrome P450 3A4 (CYP3A4) substrates)
Some medications are changed and broken down by the liver. Kava might decrease how quickly the liver breaks down some medications. Taking kava along with some medications that are broken down by the liver can increase the effects and side effects of some medications. Before taking kava, talk to your healthcare provider if you are taking any medications that are changed by the liver.

Some medications changed by the liver include lovastatin (Mevacor), ketoconazole (Nizoral), itraconazole (Sporanox), fexofenadine (Allegra), triazolam (Halcion), and many others.
Medications moved by pumps in cells (P-Glycoprotein Substrates)
Some medications are moved by pumps in cells. Kava might make these pumps less active and increase how much of some medications get absorbed by the body. This might increase the amount of some medications in the body, which could lead to more side effects. But there is not enough information to know if this is a big concern.

Some medications that are moved by these pumps include etoposide, paclitaxel, vinblastine, vincristine, vindesine, ketoconazole, itraconazole, amprenavir, indinavir, nelfinavir, saquinavir, cimetidine, ranitidine, diltiazem, verapamil, corticosteroids, erythromycin, cisapride (Propulsid), fexofenadine (Allegra), cyclosporine, loperamide (Imodium), quinidine, and others.
Medications that can harm the liver (Hepatotoxic drugs)
Kava might harm the liver. Taking kava along with medication that might also harm the liver can increase the risk of liver damage. Do not take kava if you are taking a medication that can harm the liver.

Some medications that can harm the liver include acetaminophen (Tylenol and others), amiodarone (Cordarone), carbamazepine (Tegretol), isoniazid (INH), methotrexate (Rheumatrex), methyldopa (Aldomet), fluconazole (Diflucan), itraconazole (Sporanox), erythromycin (Erythrocin, Ilosone, others), phenytoin (Dilantin), lovastatin (Mevacor), pravastatin (Pravachol), simvastatin (Zocor), and many others.
Be watchful with this combination.
Medications changed by the liver (Cytochrome P450 2D6 (CYP2D6) substrates)
Some medications are changed and broken down by the liver. Kava might decrease how quickly the liver breaks down some medications. Taking kava along with some medications that are changed by the liver can increase the effects and side effects of your medication. Before taking kava, talk to your healthcare provider if you take any medications that are changed by the liver.

Some medications that are changed by the liver include amitriptyline (Elavil), clozapine (Clozaril), codeine, desipramine (Norpramin), donepezil (Aricept), fentanyl (Duragesic), flecainide (Tambocor), fluoxetine (Prozac), meperidine (Demerol), methadone (Dolophine), metoprolol (Lopressor, Toprol XL), olanzapine (Zyprexa), ondansetron (Zofran), tramadol (Ultram), trazodone (Desyrel), and others.

Are there interactions with herbs and supplements?

Herbs and supplements that might harm the liver
There is some concern that kava might harm the liver. Using kava along with other products that might harm the liver could raise the risk of dangerous liver damage. Some of these products include androstenedione, chaparral, comfrey, DHEA, germander, niacin, pennyroyal oil, red yeast, and others.
Herbs and supplements with sedative properties
Kava can cause sleepiness or drowsiness. Using it along with other herbs and supplements that have the same effect might make you overly drowsy. Some of these herbs and supplements include 5-HTP, calamus, California poppy, catnip, hops, Jamaican dogwood, St. John's wort, skullcap, valerian, yerba mansa, and others.

Are there interactions with foods?

Using kava along with alcohol might increase drowsiness and slow reflexes dangerously. There is also some concern that using kava along with alcohol could increase the risk of liver damage.

What dose is used?

The appropriate dose of kava depends on several factors such as the user's age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for kava. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.

Other names

Ava Pepper, Ava Root, Awa, Gea, Gi, Intoxicating Long Pepper, Intoxicating Pepper, Kao, Kavain, Kavapipar, Kawa, Kawa Kawa, Kawa Pepper, Kawapfeffer, Kew, Lawena, Long Pepper, Malohu, Maluk, Maori Kava, Meruk, Milik, Piper methysticum, Poivre des Cannibales, Poivre des Papous, Rauschpfeffer, Rhizome Di Kava-Kava, Sakau, Tonga, Waka, Wurzelstock, Yagona, Yangona, Yaqona, Yaquon, Yongona.


To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.


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Last reviewed - 02/15/2015