For centuries, kava has been a ceremonial and social beverage in the South Pacific, known for its relaxing properties. In Western culture, it is used as a dietary supplement for anxiety and sleep. The active compounds responsible for its effects are kavalactones, which act as CNS depressants by modulating neurotransmitters, including gamma-aminobutyric acid (GABA). This action is where the danger lies, as many anesthetic agents also target the central nervous system, leading to potentially serious drug interactions. Perioperative care requires a complete and accurate health history, including all supplements and herbal remedies, to prevent complications arising from these interactions.
The Pharmacological Interaction with Anesthesia
Kava's primary interaction with anesthesia and other medications used during surgery is due to its potentiation of other CNS depressants. This additive effect means that when kava is in the patient's system, the sedatives and pain medication administered by an anesthesiologist may be excessively powerful. The consequences can be severe, ranging from a slower-than-expected emergence from anesthesia to respiratory depression and an increased risk of post-operative complications.
Excessive Sedation and Delayed Awakening
One of the most immediate concerns is the risk of excessive sedation. Kava, when combined with medications like barbiturates and benzodiazepines, can lead to a synergistic effect that results in profound drowsiness and a delayed or difficult wake-up period after the surgery is complete. This prolonged effect can require extended monitoring and intervention to ensure the patient fully recovers from the anesthesia.
Central Nervous System Effects
Kavalactones in kava affect neurotransmission in a way that can complicate a carefully controlled anesthetic plan. The anxiolytic and sedative effects can cause muscle weakness and reduce control (ataxia). In the perioperative setting, this could interfere with the delicate balance of medications needed to keep a patient stable and unconscious during surgery, and then to ensure a safe and steady recovery of motor and respiratory function.
Additional Perioperative Risks Associated with Kava
Besides its direct sedative properties, kava carries other risks that are particularly relevant in the surgical context:
- Liver Toxicity (Hepatotoxicity): Kava use, particularly long-term and high-dose consumption, has been linked to liver damage and, in rare cases, liver failure. The FDA has issued warnings about this risk. The combination of kava with anesthetic agents, many of which are also metabolized by the liver, can place additional stress on the organ, increasing the risk of adverse hepatic events.
- Impact on Blood Clotting: Some evidence suggests kava may interfere with blood clotting mechanisms, potentially increasing the risk of bleeding during or after surgery. While not as pronounced as with other herbs, this risk is another reason for caution and mandatory cessation before a procedure.
- Other Side Effects: Prolonged, heavy kava use has been associated with a scaly skin rash (kava dermopathy), changes in blood composition, and potentially worsening symptoms of pre-existing conditions like Parkinson's disease. These factors can complicate both the surgical procedure and the recovery process.
How Kava Interacts with Anesthetic Medications
The chemical interaction between kava and anesthetic agents is a major concern. The primary mechanism is the potentiation of other CNS depressants, as listed below:
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Benzodiazepines (e.g., Xanax, Valium): Kava can enhance the sedative effects when administered concurrently.
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Barbiturates: Theoretically, kava may have an additive effect on sedation and muscle-relaxant activity.
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Opiates: Kava may potentiate the inhibitory neurotransmission effects of opiates, leading to excessive sedation.
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Liver-metabolized Drugs: Because kava is metabolized by the liver, it can affect the breakdown of other drugs processed by the same enzymes, potentially leading to toxic concentrations.
The Crucial Pre-Surgical Withdrawal Period
Medical guidelines universally recommend that patients stop taking kava for a specific period before surgery to ensure it is completely out of their system. The most common recommendation is at least two weeks prior to a scheduled procedure. This allows the body sufficient time to metabolize and excite the kavalactones and minimize any risk of interaction. The specific timing can vary based on individual health factors and the surgical procedure, but following the established medical advice is paramount for safety.
Common Herbal Supplements and Surgical Risks: A Comparison
| Herbal Supplement | Relevant Perioperative Effects | Recommended Discontinuation Period |
|---|---|---|
| Kava | Sedation, prolonged anesthesia effects, liver toxicity | At least 2 weeks |
| Ginseng | Increased heart rate, blood pressure changes, hypoglycemia | At least 7 days |
| Ginkgo | Increased bleeding risk | At least 36 hours to 7 days, depending on source |
| Garlic | Increased bleeding risk, potential blood pressure issues | At least 7 days |
| St. John's Wort | Interferes with metabolism of many drugs (including some anesthetics), blood pressure changes | At least 5 days |
The Importance of Full Disclosure
Many patients do not consider herbal supplements to be "drugs" and may fail to mention their use to their healthcare providers. Studies show that a significant portion of patients neglect to disclose their use of herbal remedies before surgery. This lack of information can be extremely dangerous. It is vital for patients to provide their entire medical team—including surgeons, anesthesiologists, and nurses—with a complete and honest list of all medications, over-the-counter products, and herbal supplements they are taking.
Conclusion
Kava has a significant and potentially dangerous interaction with anesthesia, primarily by compounding the sedative effects of anesthetic agents and risking liver damage. It is not a benign, natural supplement in the context of surgery. To ensure patient safety and avoid complications like excessive sedation and prolonged recovery, medical professionals strongly advise stopping kava use at least two weeks before any surgical procedure. Open communication between patients and their healthcare providers about all herbal supplement use is a critical step in preventing adverse events and ensuring a smooth and safe surgical outcome.
Visit the Merck Manuals for more information on herbal supplements and surgery.
