Synthetic progestin (emergency contraception)
Levonorgestrel drug interactions: a practical overview
Drug interactions are the single biggest cause of preventable medication problems. Levonorgestrel (Levonorgestrel) interacts to varying degrees with several classes of medication and with a smaller list of foods. This page summarises the practically important ones at 1.5mg, framed for a real-world prescription review rather than an exhaustive PDF list.
High-priority interactions for Levonorgestrel
For Levonorgestrel, the most clinically relevant interactions are typically with strong CYP3A4 inhibitors and inducers, with cardiovascular medications (notably nitrates for several Synthetic progestin (emergency contraception) agents), with central nervous system depressants, and with medications affecting blood pressure or heart rate. In emergency contraception, levonorgestrel works primarily by delaying or inhibiting ovulation when taken before the LH surge.
Working with the pharmacist
A pharmacist review of all current medications is the practical safeguard against unintended interactions with Levonorgestrel. According to the prescribing information for Levonorgestrel, the full medication list — prescription, OTC, supplements and recreational substances — should be reviewed before starting and at every dose change at 1.5mg.
Frequently asked questions
What's the most important Levonorgestrel interaction to know? ▾
For most Synthetic progestin (emergency contraception) medications, the highest-priority interaction is with nitrate medications used for chest pain — this combination is often a hard contraindication. After that, strong CYP3A4 inhibitors (some antifungals, macrolides) are the next concern at routine 1.5mg doses.
Do I need to tell the pharmacist about supplements? ▾
Yes. Supplements and herbal products can interact with Levonorgestrel in ways that prescription drug-drug interaction databases miss. The pharmacist needs the complete picture — including supplements like St John's Wort, grapefruit-containing products and high-dose vitamins — to flag risks at 1.5mg.
Products containing Levonorgestrel
More on Levonorgestrel
- With alcoholLevonorgestrel and alcohol — is it safe to drink?
- With foodShould Levonorgestrel be taken with food?
- Side effectsLevonorgestrel side effects: common, rare and warning signs
- Dosage guideLevonorgestrel dosage guide: how much to take and when
- OnsetHow fast does Levonorgestrel start working?
- DurationHow long does Levonorgestrel last?
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.