Kava - Diclofenac Interaction
Herbal: Kava
Also Known As: Piper methysticum, 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
Drug: Diclofenac
Brand names:
Zorvolex
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
May 18, 2025
Interaction Details
Diclofenac is classified as belonging to the following category: Hepatotoxic Drugs
Theoretically, using kava with hepatotoxic drugs might increase the risk of liver damage.
Kava has been linked with over 100 cases of hepatotoxicity. Most cases occur with excessive and prolonged use. There is some concern that kava can adversely affect the liver, especially when used in combination with hepatotoxic drugs.
Interaction Rating
Likelihood of Occurrence
PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
References
- Escher M, Desmeules J, Giostra E, Mentha G. Hepatitis associated with Kava, a herbal remedy for anxiety. BMJ 2001;322:139.
- Russmann S, Lauterburg BH, Helbling A. Kava hepatotoxicity [letter]. Ann Intern Med 2001;135:68-9.
- Liver Toxicity With Kava. Pharmacist's Letter/Prescriber's Letter. January 2001.
- Consultation letter MLX 286: Proposals to prohibit the herbal ingredient Kava-Kava (Piper methysticum) in unlicensed medicines. Medicines Control Agency, United Kingdom, July 19, 2002.
- Li XZ, Ramzan I. Role of ethanol in kava hepatotoxicity. Phytother Res 2010;24:475-80.
- Chanwai, L. G. Kava toxicity. Emergency Medicine 2002;12:142-145.
Interaction Details
Diclofenac is classified as belonging to the following category: Cytochrome P450 2C9 (Cyp2C9) Substrates
Theoretically, kava might increase levels of CYP2C9 substrates.
In vitro research shows that kava significantly inhibits CYP2C9 enzymes. This effect has not yet been reported in humans.
Interaction Rating
Likelihood of Occurrence
PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
References
- Mathews JM, Etheridge AS, Black SR. Inhibition of human cytochrome P450 activities by kava extract and kavalactones. Drug Metab Dispos 2002;30:1153-7.
- Unger M, Frank A. Simultaneous determination of the inhibitory potency of herbal extracts on the activity of six major cytochrome P450 enzymes using liquid chromatography/mass spectrometry and automated online extraction. Rapid Commun Mass Spectrom 2004;1
Kava Overview
Kava is a tropical plant native to the Pacific Islands. The roots of the plant contain kavalactones, which are known to have sedative and relaxing effects. Kava has traditionally been used in social and cultural settings for its relaxant effects and is available as a dietary supplement to help with symptoms of anxiety and stress. It is important to note that Kava has been linked to causing liver damage and must be used cautiously, although the results of studies in this regard are mixed. Nevertheless, kava is banned in some parts of the world (e.g., the UK).
Diclofenac Overview
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Diclofenac capsules (Zipsor, Zorvolex) and tablets (Cataflam) are used to relieve mild to moderate pain. Diclofenac extended-release tablets (Voltaren XR), tablets (Cataflam), and delayed-release tablets (available generically) are used to relieve pain, tenderness, swelling, and stiffness caused by osteoarthritis (arthritis caused by a breakdown of the lining of the joints), and rheumatoid arthritis (arthritis caused by swelling of the lining of the joints). Diclofenac extended-release tablets and delayed-release tablets are also used to treat ankylosing spondylitis (arthritis that mainly affects the spine). Diclofenac tablets (Cataflam) are also used to treat painful menstrual periods. Diclofenac solution (Cambia) is used to treat migraine headaches in adults, but cannot be used to prevent migraines or to treat other types of headaches. Diclofenac is in a class of medications called NSAIDs. It works by stopping the body's production of a substance that causes pain, fever, and inflammation.
Kava - More Interactions
Kava interacts with 1127 drugs
Interaction Rating Key
These severity listings are for informational use only. Never start, stop or otherwise change your therapy before speaking with your provider.
| Major | The combined use of these agents is strongly discouraged as serious side effects or other negative outcomes could occur. |
| Moderate | Use cautiously under the care of a healthcare professional or avoid this combination. A significant interaction or negative outcome could occur. |
| Minor | Be aware that there is a chance of an interaction. Watch for warning signs of a potential interaction. |
| Unknown | No interactions have been reported or no interaction data is currently available. |
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Parts of this content are provided by the Therapeutic Research Center, LLC.
DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
© 2021 Therapeutic Research Center, LLC
Drug descriptions are provided by MedlinePlus.
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In addition to being a clinical pharmacist specializing in pharmacotherapy, Dr. Brian Staiger is a registered herbalist through the American Herbalist Guild. He has combined his passion for pharmacy practice with the study of medical ethnobotany to improve patient care. Feel free to reach out about any of your herbal or medication questions!
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