Medication questions Safety and side effects
Can you give blood if you take finasteride?
Short answer
Not while you are taking finasteride tablets. The UK Blood Services' donor guidelines say you must not donate if you have taken finasteride in the last 4 weeks, whether for hair loss or the prostate. For dutasteride the wait is 6 months. If you have only ever used topical finasteride, the guidelines allow you to donate.
Key facts
- Finasteride tablets: do not donate within 4 weeks of the last dose (JPAC, any dose or reason).
- Dutasteride: do not donate within 6 months of the last dose.
- Topical finasteride only: JPAC guidance says the donor can be accepted.
- Always tell the donor service about every medicine you use.
The rule for finasteride and dutasteride
Blood donors in the UK are assessed against the donor selection guidelines published by JPAC, the professional advisory committee for the UK Blood Services. Its entry on anti-androgens (medicines that reduce the effect of male hormones) says you must not donate if you have taken:
Finasteride (Propecia, Proscar) in the last 4 weeks
Dutasteride (Avodart) in the last 6 months
The finasteride rule is the same whether you take the 1 mg dose for hair loss or the 5 mg dose for an enlarged prostate. The guidance does not separate them by dose or reason. Scotland's blood service puts it the same way: you cannot give blood while taking these medicines "and for a variable length of time afterwards".
Why the rule exists
The medicine is safe for you, but your blood could be given to someone else. JPAC explains that finasteride and dutasteride "can cause abnormal development of the sexual organs of a male baby within the womb". Donated blood can be given to a pregnant woman, so the waiting period lets the medicine clear from your blood first.
The longer wait for dutasteride reflects how long it stays in the body. The UK Avodart product information gives its half-life (the time for the level in the blood to fall by half) as about 3 to 5 weeks, compared with around 5 to 6 hours for finasteride. Our half-life explainer covers why that matters.
The same concern about a developing male baby is why pregnant women should not handle crushed finasteride tablets or leaking dutasteride capsules. Our page on finasteride and trying for a baby covers that side.
Topical finasteride and minoxidil
JPAC's entry on alopecia (hair loss) treats topical products differently. It says: "If the donor has only used topical finasteride (e.g. spray, foam or lotion), accept." So if your only finasteride is a scalp solution, such as a topical finasteride and minoxidil combination, the guidelines allow donation. If you take tablets as well, the 4-week rule for tablets applies.
The same entry says a donor taking minoxidil or spironolactone who is not under specialist follow-up can be accepted. The final decision always rests with the donor service on the day, so tell them about every medicine and product you use, including anything you apply to your scalp.
If you want to give blood regularly
Do not stop a prescribed medicine just to donate without talking to your prescriber first. With finasteride, a short break before a donation is possible in principle, but the hair benefit fades if you stop for longer: the UK product information says it begins to reverse by about 6 months. Our page on stopping finasteride explains the timeline.
If giving blood matters to you, mention it at your assessment or review. It is a legitimate factor when you and the doctor decide on a treatment plan. If you are starting out, the free online assessment is the place to raise it. The guidelines are updated regularly, so check with the donor service before you book.
Whatever you take, the MHRA safety warnings about mood and sexual side effects still apply. See our MHRA safety updates page.
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Start your free assessment →Related questions
Can I give blood if I take finasteride for hair loss?
Not while you are taking the tablets. UK donor guidelines say you must not donate if you have taken finasteride in the last 4 weeks. The rule is the same for the 1 mg hair loss dose and the 5 mg prostate dose.
I only use a topical finasteride spray. Can I donate?
JPAC's alopecia guidance says a donor who has only used topical finasteride, such as a spray, foam or lotion, can be accepted. Tell the donor service exactly what you use, because they make the final decision.
How long after stopping dutasteride can I give blood?
Six months after your last capsule. Dutasteride has a half-life of about 3 to 5 weeks, so it takes much longer to leave the body than finasteride.
Does minoxidil stop me giving blood?
Not usually. JPAC's alopecia guidance says donors taking minoxidil who are not under specialist follow-up can be accepted. The donor service will ask about your health and medicines on the day.
Why is finasteride a problem in donated blood if it is safe for me?
Because the person receiving your blood might be pregnant. Finasteride and dutasteride can affect the development of a male baby's sex organs, so the waiting period protects recipients rather than you.
Sources
- JPAC, Guidelines for the UK Blood Transfusion Services: Anti-androgens (whole blood, September 2026)
- JPAC, Guidelines for the UK Blood Transfusion Services: Alopecia (whole blood, August 2026)
- Scottish National Blood Transfusion Service: Medications
- Avodart 0.5 mg soft capsules: summary of product characteristics (eMC, revised 11 August 2026)
Facts checked against these sources on 4 October 2026. This page is general information, not personal medical advice. Read our editorial policy.