st johns wort: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
st johns wort: clinical details
Prescribing considerations
- Establish whether symptoms require assessment rather than self-treatment.
- Complete a medication and contraception review before initiation or discontinuation.
- Ensure the surgical or anaesthetic team knows about current or recent use.
- Advise avoidance of excessive sunlight and ultraviolet exposure.
Contraindications and cautions
- Hypersensitivity to the extract or excipients.
- Known dermal photosensitivity, phototherapy or photodiagnostic procedures.
- Concurrent warfarin, ciclosporin, systemic tacrolimus, specified HIV protease inhibitors or irinotecan.
Monitoring
- Monitor for deterioration, depressive illness, mania or significant behavioural change.
- Assess clinical response and medicine-specific laboratory parameters where exposure to an interacting medicine may have changed.
- Review breakthrough bleeding or suspected contraceptive failure promptly.
Clinical pharmacology
Hyperforin activates the pregnane X receptor, inducing CYP3A4, CYP2C9, CYP2C19 and P-glycoprotein; CYP1A2 induction is also described. Serotonergic interactions occur with antidepressants and triptans.
Formulation and product differences
- Selected products are oral film-coated tablets containing a dry ethanolic extract from aerial parts of Hypericum perforatum.
- Advice from the selected SmPC should not automatically be applied to differently formulated or unlicensed products.
st johns wort interactions
St John’s wort has many clinically important interactions. A pharmacist or prescriber should review all medicines before it is started or stopped.
Hormonal contraception, including emergency contraception
It can reduce hormone exposure, causing breakthrough bleeding and contraceptive failure; concurrent use should be avoided.
Antidepressants, other serotonergic medicines and triptans
Combining them may increase serotonergic effects and the risk of serotonin syndrome.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.