Common and Allergic Side Effects
Kampo formulations can cause common side effects such as nausea, vomiting, diarrhea, abdominal discomfort, and loss of appetite, likely due to herbal ingredients. Formulas with rhubarb (Rhei Rhizoma) may cause diarrhea. Allergic reactions, including skin rashes, itching, and respiratory issues, are also possible. Some formulas can induce drowsiness or fatigue, which is important to consider if driving or operating machinery.
Serious and Organ-Specific Adverse Effects
More severe, organ-specific adverse events are associated with particular herbs within Kampo formulas. Concerns include liver injury, lung injury, pseudoaldosteronism, and mesenteric phlebosclerosis.
Liver Injury
Drug-induced liver injury (DILI) is a significant risk, often linked to Scutellariae Radix ('ogon') and possibly involving an allergic mechanism. Symptoms can be non-specific, emphasizing the need for liver function monitoring.
Lung Injury
Interstitial pneumonia is an immunoallergic reaction associated with Kampo, particularly formulas containing Scutellariae Radix. Symptoms include fever, cough, and shortness of breath.
Pseudoaldosteronism
This disorder is caused by glycyrrhizin in Glycyrrhizae Radix (licorice root, 'kanzo'). It can lead to high blood pressure, low potassium, and edema, with severe cases potentially causing muscle problems, irregular heartbeats, and heart failure.
Mesenteric Phlebosclerosis
Long-term use (over 5 years) of Kampo with Gardeniae Fructus (gardenia fruit, 'sanshishi') can cause this condition, leading to abdominal pain, diarrhea, constipation, and distension. Severe cases may require surgery.
Drug Interactions and Compounding Risks
Kampo can interact with conventional medications. Some herbs may affect liver enzymes crucial for drug metabolism, while metallic additives in some preparations can alter drug absorption. Taking multiple Kampo formulas or combining them with other drugs increases the risk of polypharmacy and potential overdose of specific ingredients, such as licorice.
Comparison of Major Serious Side Effects
| Feature | Liver Injury (Hepatotoxicity) | Lung Injury (Pneumonitis) | Pseudoaldosteronism | Mesenteric Phlebosclerosis |
|---|---|---|---|---|
| Associated Herb | Scutellariae Radix ('ogon') | Scutellariae Radix ('ogon') | Glycyrrhizae Radix ('kanzo') | Gardeniae Fructus ('sanshishi') |
| Mechanism | Immunoallergic reaction | Immunoallergic reaction | Inhibition of 11β-HSD II by glycyrrhizin | Genipin-induced damage from long-term use |
| Onset | Short latency period (weeks to months) | Can occur after weeks or months | Often occurs with prolonged or high-dose use | Occurs after long-term use (years) |
| Monitoring | Regular liver function tests | Awareness of respiratory symptoms | Blood pressure and serum potassium checks | CT or colonoscopy for long-term users |
Conclusion
Kampo medicine can provide benefits but carries risks, from common digestive issues to severe organ damage. Serious effects are often linked to specific herbs like Scutellariae Radix, Glycyrrhizae Radix, and Gardeniae Fructus. It is vital for patients to inform healthcare providers about all Kampo use to manage interactions and monitor for adverse reactions. Proper diagnosis and cautious use are essential for safety.
For further details on the toxicological considerations of Kampo medicines, a review article is available via the National Institutes of Health(https://pubmed.ncbi.nlm.nih.gov/15138045/).
