Kava (Piper methysticum), a plant native to the South Pacific islands, has a long history of use in traditional ceremonies and for its relaxing, anxiety-reducing effects [1.2.3, 1.5.2]. Its active compounds, called kavalactones, interact with the central nervous system to produce feelings of calm and well-being [1.5.2]. However, despite its potential benefits, kava is not safe for everyone. Regulatory bodies like the U.S. Food and Drug Administration (FDA) have issued warnings about its potential for causing severe liver damage [1.5.4]. Knowing the specific situations and conditions where kava is contraindicated is essential for safe use.
The Foremost Concern: Liver Toxicity (Hepatotoxicity)
The most significant risk associated with kava is hepatotoxicity, or liver damage [1.2.3]. Since 1999, there have been reports in Europe and the United States of severe liver injury, including hepatitis, cirrhosis, and liver failure, in people who used kava supplements [1.7.3, 1.6.4]. Some cases were so severe that they required a liver transplant [1.7.3].
Because of this risk, individuals with any pre-existing liver condition should never use kava [1.2.2]. This includes:
- Hepatitis (viral or other forms)
- Cirrhosis
- Fatty liver disease
- Any history of liver problems or elevated liver enzymes [1.3.3]
The World Health Organization (WHO) notes that the risk of liver toxicity is more likely with overdosing, excessive alcohol intake, pre-existing liver disease, and drug interactions [1.2.3]. The quality of the kava product also plays a role; preparations made from the plant's roots using water-based extraction are generally considered safer than those made with ethanol or acetone, or those containing the plant's leaves and stems [1.2.3, 1.3.3].
Absolute Contraindications: Groups Who Must Avoid Kava
Beyond liver conditions, several other groups should completely abstain from using kava due to significant health risks.
Pregnant or Breastfeeding Women
Kava is considered unsafe for use during pregnancy and while breastfeeding [1.8.4]. Chemicals in kava can pass into breast milk and may harm the infant [1.8.4]. There is also concern it could affect the uterus during pregnancy [1.8.4]. A recent case report described a newborn developing a scaly skin rash (ichthyosiform dermopathy) linked to the mother's kava use during pregnancy [1.8.2].
Individuals with Parkinson's Disease
Kava may interfere with the effects of dopamine and can worsen symptoms of Parkinson's disease [1.2.1, 1.6.6]. It may decrease the effectiveness of medications like levodopa, which is used to treat the condition [1.6.6]. Therefore, individuals with Parkinson's should avoid kava [1.6.6].
People with Depression
Some sources suggest that kava can worsen symptoms of endogenous depression [1.2.1, 1.6.5]. Anyone with a diagnosis of depression or bipolar disorder should consult their healthcare provider before considering kava, as it may not be appropriate [1.8.1].
Children
Kava is not recommended for use in children [1.2.2]. There is a lack of research on its safety and effects in pediatric populations.
Kava and Medication: A Risky Combination
Kava can interact with numerous prescription and over-the-counter (OTC) medications, often by affecting how the liver metabolizes them through enzymes known as the cytochrome P450 system [1.4.1, 1.4.4]. This can lead to increased medication levels, heightened side effects, or reduced efficacy. Combining kava with other central nervous system depressants is particularly dangerous.
Kava Drug Interactions Comparison Table
| Medication or Substance Class | Examples | Potential Interaction and Risk | Sources |
|---|---|---|---|
| Central Nervous System (CNS) Depressants | Alcohol, Benzodiazepines (e.g., Xanax, Valium), Barbiturates, Opioids | Kava can enhance the sedative effects, leading to excessive drowsiness, impaired coordination, slowed breathing, and in severe cases, coma or death. The risk of liver damage is also increased when combined with alcohol. | [1.4.3, 1.4.5, 1.2.5] |
| Hepatotoxic Drugs (Liver-damaging) | Acetaminophen (Tylenol), certain statins (e.g., atorvastatin), amiodarone, methotrexate | Taking kava with other drugs that can harm the liver significantly increases the risk of severe liver injury. Kava has been shown to enhance acetaminophen-induced liver toxicity in lab studies. | [1.3.5, 1.2.5] |
| Anti-Parkinson's Medication | Levodopa, Ropinirole | Kava may interfere with dopamine pathways, reducing the effectiveness of these medications and potentially worsening Parkinson's symptoms. | [1.6.6, 1.6.5] |
| Anesthetics | General anesthesia used during surgery | Kava can intensify the effects of anesthetics and other sedatives used during and after surgery. It is recommended to stop kava use at least 2 weeks before a scheduled surgery. | [1.2.6, 1.6.5] |
| Various Drugs Metabolized by CYP450 Enzymes | Some antidepressants, antipsychotics (e.g., haloperidol), 'blood thinners' (e.g., warfarin), and others | Kava can inhibit liver enzymes (like CYP1A2, 2C9, 2C19, 2E1, 3A4), which may increase the concentration and side effects of many other medications. Always consult a healthcare provider. | [1.4.4, 1.3.5, 1.4.2] |
Other Situational Risks
- Driving or Operating Machinery: Due to its sedative effects, you should not drive or operate heavy machinery after taking kava, as it can impair motor skills and reaction time [1.2.3].
- Long-Term, Heavy Use: Chronic, heavy consumption of kava can lead to a condition called "kava dermopathy," a scaly, yellow skin rash that is reversible upon stopping use [1.2.1, 1.5.2]. It can also cause weight loss, apathy, and changes in blood cells [1.5.2].
- Before Surgery: Kava should be discontinued at least two weeks before any scheduled surgery to avoid dangerous interactions with anesthesia and other medications [1.6.5].
Conclusion: Prioritize Safety Through Consultation
While kava has been used for centuries for its calming properties, its potential for serious side effects and drug interactions cannot be overlooked. The risk of liver damage is the most critical concern, making it essential for anyone with a history of liver issues to avoid it completely. Likewise, pregnant and breastfeeding women, individuals with Parkinson's disease, and those taking a wide range of medications should steer clear. Given the complexity of its interactions and the seriousness of the risks, it is imperative to consult with a healthcare professional before using any kava-containing product.
For more information on kava safety, you can visit the National Center for Complementary and Integrative Health (NCCIH).
