Propecia drug interactions: a practical overview
Drug interactions are the single biggest cause of preventable medication problems. Propecia (Finasteride) interacts to varying degrees with several classes of medication and with a smaller list of foods. This page summarises the practically important ones at 1mg, framed for a real-world prescription review rather than an exhaustive PDF list.
High-priority interactions for Propecia
For Finasteride, the most clinically relevant interactions are typically with strong CYP3A4 inhibitors and inducers, with cardiovascular medications (notably nitrates for several Male and Female Pattern Hair Loss agents), with central nervous system depressants, and with medications affecting blood pressure or heart rate. DHT, produced from testosterone by 5-alpha-reductase, drives miniaturisation of scalp hair follicles in genetically susceptible men, gradually shortening anagen growth phases until follicles produce o…
Working with the pharmacist
A pharmacist review of all current medications is the practical safeguard against unintended interactions with Propecia. According to the prescribing information for Finasteride, the full medication list — prescription, OTC, supplements and recreational substances — should be reviewed before starting and at every dose change at 1mg.
Frequently asked questions
What's the most important Propecia interaction to know? ▾
For most Male and Female Pattern Hair Loss 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 1mg doses.
Do I need to tell the pharmacist about supplements? ▾
Yes. Supplements and herbal products can interact with Propecia 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 1mg.
More on Propecia
- With alcoholPropecia and alcohol — is it safe to drink?
- With foodShould Propecia be taken with food?
- Side effectsPropecia side effects: common, rare and warning signs
- Dosage guidePropecia dosage guide: how much to take and when
- OnsetHow fast does Propecia start working?
- DurationHow long does Propecia last?
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.