Honokiol is a natural compound found in the bark, seed cones, and leaves of Magnolia trees, native to regions like Southeast Asia, China, Japan, and the Southeastern United States. For centuries, it has been used in traditional medicine systems, including Chinese, Korean, and Japanese practices. Magnolia bark extracts have been used for their analgesic properties and to address conditions like anxiety and mood disorders. Modern research continues to explore honokiol for its diverse properties, including potential anti-tumor, anti-inflammatory, and neuroprotective effects.
Commonly Reported Side Effects
While generally well-tolerated, honokiol can cause adverse reactions. Gastrointestinal issues are commonly reported, including nausea, heartburn, and diarrhea. Neurological effects like drowsiness or dizziness have also been noted, consistent with its calming properties.
At very high doses, concerns about neurotoxicity suggest careful dosage consideration. Skin reactions, such as allergic dermatitis, have been documented, particularly with topical magnolia bark extract.
Potential Drug Interactions
Honokiol may interact with certain medications. Its calming effects may increase the effects of central nervous system depressants, such as sedatives. Honokiol also inhibits several cytochrome P450 (CYP) enzymes (e.g., CYP1A2, CYP2C8, CYP2C9, CYP2C19) and UDP-glucuronosyltransferase 1A9 (UGT1A9), which metabolize many drugs.
Inhibiting these enzymes can alter drug metabolism, potentially increasing drug levels and side effects. For example, its inhibition of CYP2C19 suggests caution with drugs like diazepam, phenytoin, or omeprazole. Its effect on UGT1A9 could also impact drugs like propofol or S-etodolac. Animal studies also indicate that magnolol, another magnolia bark compound, may have antiplatelet activities, increasing bleeding risk with blood thinners.
Specific Populations and Precautions
Certain populations should exercise caution or avoid honokiol due to limited safety data or risks. Pregnant and breastfeeding individuals should avoid honokiol due to insufficient safety data. Animal studies show honokiol and magnolol can block uterine contractions, posing a risk during pregnancy.
Individuals undergoing surgery should also be cautious due to its sedative effects and possible interactions with anesthesia. Its potential to increase bleeding risk, observed with magnolol’s antiplatelet activities, is also a concern for surgical patients. People with pre-existing medical conditions, such as liver or kidney issues, should consult a healthcare professional, as honokiol is extensively metabolized in the liver. Individuals with low blood pressure should also be careful, as some research suggests magnolia may lower blood pressure.