⚠️ Mechanism
St Johns Wort is a strong inducer of CYP3A4, which increases metabolism of CYP3A4 substrates, potentially reducing their plasma concentrations and therapeutic efficacy.
📋 Effect
Reduced plasma levels of nifedipine (calcium-channel-blockers), potentially leading to therapeutic failure.
💊 Management
Monitor for reduced efficacy of nifedipine. Dose adjustment may be necessary. Consider alternative supplement or consult healthcare provider.
Plain Language Summary
This combination is dangerous because St. John's Wort can cause your body to break down calcium channel blockers much faster than normal. This can lead to lower levels of the medication in your system, which may prevent the drug from working effectively.
Source
Flockhart CYP450 Table (drug-interactions.medicine.iu.edu)
Supporting Research
The effect of Hypericum perforatum on postmenopausal symptoms and depression: A randomized controlled trial
Hypericum extract LI 160 and fluoxetine in mild to moderate depression: a randomized, placebo-controlled multi-center study in outpatients
[Hypericum perforatum extract in treatment of mild to moderate depression. Clinical and pharmacological aspects]
Hypericum perforatum versus fluoxetine in the treatment of mild to moderate depression
Efficacy of continuation treatment with hypericum perforatum in depression
Predicting stable treatment response in patients with major depression treated with hypericum extract WS 5570/5572
Adverse Event Profile: St Johns Wort
Medical Disclaimer: This interaction record is for informational and educational purposes only and does not constitute medical advice. Drug-supplement interactions can be dangerous. Always consult your healthcare provider or pharmacist before combining any supplement with prescription medications. Do not stop or change any medication without professional guidance.