5-alpha-reductase inhibitor (type II)
Finasteride with vitamins, minerals and herbal supplements
Supplements are widely used and rarely disclosed to the prescriber, which makes them a common source of unrecognised interactions with Finasteride (Finasteride). Many supplements are inert or harmless, but a small number — particularly herbal extracts and high-dose vitamins — can affect how Finasteride works at 1mg.
High-priority supplement interactions
St John's Wort is the herbal supplement most often flagged for interactions because it strongly induces CYP3A4 and reduces plasma levels of many medications including several 5-alpha-reductase inhibitor (type II) agents. Grapefruit-extract supplements work in the opposite direction. High-dose vitamin K affects anticoagulants. Calcium and iron can chelate certain antibiotics.
Practical disclosure
According to the prescribing information for Finasteride, the medication list reviewed by the pharmacist should always include supplements. Most multivitamins at standard doses do not interact meaningfully with Finasteride at 1mg, but anything herbal, anything single-ingredient at high dose, and anything new started recently is worth flagging.
Frequently asked questions
Are vitamins safe with Finasteride? ▾
Standard-dose multivitamins are usually fine with Finasteride at 1mg. High-dose single vitamins (e.g. vitamin K, large doses of vitamin E) can interact with specific medication classes; the pharmacist confirms whether these matter for Finasteride.
Should I tell the pharmacist about herbal supplements? ▾
Yes — particularly St John's Wort, ginseng, ginkgo, garlic extract and any concentrated herbal formulation. Several of these have meaningful interactions with prescription medications including some agents in the 5-alpha-reductase inhibitor (type II) class.
Products containing Finasteride
More on Finasteride
- With alcoholFinasteride and alcohol — is it safe to drink?
- With foodShould Finasteride be taken with food?
- Side effectsFinasteride side effects: common, rare and warning signs
- Dosage guideFinasteride dosage guide: how much to take and when
- OnsetHow fast does Finasteride start working?
- DurationHow long does Finasteride last?
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.