Formulary
St John's wort: Indications, Dosing, Side Effects and Interactions
John's wort St John's wort is a herbal medicine included only for its potential to interact with drugs.
MedNext Academy | 3 min read
St John's wort: Indications, Dosing, Side Effects and Interactions
John's wort St John's wort is a herbal medicine included only for its potential to interact with drugs.
Drug action
John's wort St John's wort is a herbal medicine included only for its potential to interact with drugs.
Interactions
**Severe interactions:**
- Concomitant administration of strong or moderate CYP3A inducers, (such as rifampicin, rifabutin, carbamazepine, phenobarbital, phenytoin, efavirenz and St John's wort), is expected to significantly...
- St John's Wort Severe hypotension and delayed emergence from anaesthesia with halogenated inhalational anaesthetics have been reported in patients treated long-term with St John's Wort.
- Contraindications of concomitant use Primidone and its main metabolite phenobarbital are strong inducers of cytochrome P450 and thus lead to life-threatening situations due to the risk of decreased...
**Other interactions (51):**
- Herbal preparations containing St John's Wort ( Hypericum perforatum ) may induce the metabolism of estrogens and progestogens.
- Concomitant use with precautions - Moderate CYP3A4 inhibitors: the concomitant use of ivabradine with other moderate CYP3A4 inhibitors (e.g.
- The combination of ivabradine 10 mg twice daily with St John's Wort was shown to reduce ivabradine AUC by half.
- The intake of St John's Wort should be restricted during the treatment with ivabradine.
- HERBAL PRODUCTS St John's wort (Hypericum perforatum) Not studied.
- Inducers of CYP2C19 and/or CYP3A4 Active substances known to induce CYP2C19 or CYP3A4 or both (such as rifampicin and St John's wort) may lead to decreased omeprazole serum levels by increasing...
Medicinal forms
Medicinal forms No licensed medicines listed.
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
Inside MedNext for this topic
- 411 MedNext-authored chapters
- 80,000+ MCQ bank
- 15 study modes
- Growing visual cheat sheets
Study modes
- Notes
- MCQ
- Audio
- Video
- Visual
- 3D Anatomy
- Trace
- Flashcards
- Mnemonics
- Image Bank
- Clinical
- Microscopy
- Audio QBank
- Cadaver
- Book Match
Continue reading
Subject HubPharmacology Hub
All pharmacology resources in one place.
Drug SchedulesIndian Drug Schedules
Schedule H, H1, X and G classifications.
FormularyBrowse all drugs
Search 1,850+ drug profiles.
Study St John's wort in the MedNext app
Challenge yourself with targeted pharmacology MCQs on this drug class. Every explanation links back to the chapter that teaches the concept.
Start drug challengeExplore the full formulary

