Understanding Kava and Its Effects
Kava, derived from the root of the Piper methysticum plant, is a traditional beverage from the Pacific Islands known for its relaxing and anxiety-reducing properties [1.5.3, 1.4.2]. Its active compounds, called kavalactones, affect the brain and central nervous system (CNS), primarily by influencing gamma-aminobutyric acid (GABA) receptors, which results in sedative and muscle-relaxant effects [1.4.3, 1.4.4]. While used by some as an alternative remedy for anxiety and stress, kava carries significant risks, especially when taken with other substances. The U.S. Food and Drug Administration (FDA) issued a consumer advisory in 2002 regarding the potential for severe liver injury associated with kava-containing products [1.3.3, 1.7.1]. These risks are amplified through drug interactions, which can occur through two primary mechanisms.
How Kava Interacts with Medications
Kava's interactions are primarily twofold:
- Pharmacodynamic Interactions: This occurs when kava and another substance have similar effects on the body. Because kava is a CNS depressant, taking it with other depressants like alcohol or sedatives can lead to an additive effect, causing excessive drowsiness, impaired motor control, and in severe cases, coma or respiratory depression [1.4.1, 1.8.4]. One case report detailed a patient becoming semicomatose after combining kava with the benzodiazepine alprazolam [1.8.5].
- Pharmacokinetic Interactions: Kava can interfere with the body's ability to metabolize (break down) other drugs. It achieves this by inhibiting cytochrome P450 (CYP) enzymes in the liver [1.2.1, 1.6.2]. These enzymes, such as CYP2D6, CYP3A4, and CYP2C9, are responsible for processing a vast majority of medications [1.6.1, 1.6.2]. By inhibiting these enzymes, kava can cause other drugs to build up in the body to toxic levels, increasing their effects and side effects [1.6.3].
Medications and Substances to Avoid with Kava
Due to these mechanisms, a wide range of medications are contraindicated with kava. It is essential to consult a healthcare provider before using kava if you are taking any prescription or over-the-counter drugs.
Central Nervous System (CNS) Depressants
This is the most critical category of interacting substances. Combining kava with any CNS depressant can lead to dangerous levels of sedation and cognitive impairment [1.3.1].
- Alcohol: This combination should always be avoided. Both are CNS depressants and both can be taxing on the liver. Using them together significantly increases the risk of both excessive sedation and severe liver damage [1.7.2, 1.7.4].
- Benzodiazepines: Medications like alprazolam (Xanax), diazepam (Valium), and lorazepam (Ativan) are used for anxiety. Combining them with kava can lead to extreme drowsiness, disorientation, and even a comatose state [1.4.3, 1.8.1].
- Barbiturates: Drugs like phenobarbital, used for seizures or as sedatives, can have their depressant effects dangerously amplified by kava [1.3.2, 1.4.1].
- Other Sedatives/Hypnotics: This includes sleep aids like zolpidem (Ambien) and other herbal supplements with sedative properties such as valerian, St. John's wort, and melatonin [1.2.5].
Medications Affecting the Liver (Hepatotoxic Drugs)
Given that kava itself is linked to liver toxicity, combining it with other drugs that are hard on the liver is particularly risky [1.5.4]. The FDA explicitly warns individuals with existing liver problems or those taking drugs that can affect the liver to consult a physician before using kava [1.3.3].
- Acetaminophen (Tylenol): A common over-the-counter pain reliever that can cause liver damage in high doses. Taking it with kava may increase this risk [1.3.4, 1.2.2].
- Certain Antifungals, Statins, and other prescription drugs: Medications like methotrexate and isoniazid are known to be potentially hepatotoxic, and the risk is compounded when taken with kava [1.3.2, 1.5.4].
Medications for Parkinson's Disease
Kava may interfere with the action of dopamine in the brain [1.10.4].
- Levodopa: This is a primary medication for Parkinson's disease. Kava can decrease its effectiveness, potentially worsening Parkinson's symptoms [1.10.3, 1.10.2].
- Ropinirole (Requip): Kava can inhibit the breakdown of this medication, leading to increased side effects and dopaminergic toxicity [1.2.3, 1.2.4].
Psychiatric Medications
Beyond benzodiazepines, other psychiatric drugs can also interact negatively.
- Antidepressants: Combining kava with SSRIs like sertraline (Zoloft) can increase side effects such as drowsiness and impaired judgment [1.9.2]. It should not be taken with MAOIs, as kava may have similar properties, leading to additive effects [1.3.3].
- Antipsychotics: Drugs like haloperidol (Haldol) are broken down by liver enzymes that kava inhibits. This can lead to higher levels of the medication and increased side effects [1.6.3, 1.2.4].
| Drug/Substance Class | Examples | Primary Risk of Interaction | Source(s) |
|---|---|---|---|
| CNS Depressants | Alcohol, Benzodiazepines (Xanax), Barbiturates | Additive sedative effects, excessive drowsiness, impaired motor control, potential coma | [1.4.1, 1.8.4] |
| Hepatotoxic Drugs | Acetaminophen (Tylenol), Methotrexate | Increased risk of severe liver damage and failure | [1.2.2, 1.5.4] |
| Parkinson's Medications | Levodopa, Ropinirole | Decreased effectiveness of the medication, worsening of Parkinson's symptoms | [1.10.4, 1.10.1] |
| Antidepressants | SSRIs (Zoloft), MAOIs | Increased side effects like dizziness and drowsiness; potentially dangerous with MAOIs | [1.9.2, 1.3.3] |
| Antipsychotics | Haloperidol (Haldol) | Increased levels of the medication in the body, leading to more side effects | [1.6.3] |
Conclusion: Prioritize Safety and Medical Advice
While kava is promoted for its calming effects, its potential for serious drug interactions cannot be overlooked. The herb's impact on the central nervous system and liver metabolism means it can dangerously alter the effects of many common medications. The risk of severe liver toxicity, though considered rare, has led to hospitalizations and even liver transplants [1.5.2, 1.5.3]. It is absolutely critical to avoid combining kava with alcohol, sedatives, and medications for Parkinson's disease. For anyone taking any medication, consulting with a doctor or pharmacist is a non-negotiable step before considering kava use. This ensures that potential interactions are identified and life-threatening complications are avoided.
Authoritative Link: For more information on kava safety, consult the National Center for Complementary and Integrative Health (NCCIH).
