Answer
Some medicines for epilepsy, tuberculosis or HIV, griseofulvin and St John's wort can reduce exposure. A pharmacist or clinician may advise another emergency contraceptive option.
Sources for this answer
- Levonorgestrel 1.5mg Tablets (P) — Current selected SmPCemc · Summary of Product Characteristics
- NHSNHS · NHS medicine guidance
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.