Finasteride and family planning: what do we know about sperm, a pregnant partner, and the spray?

I've been taking finasteride for my hair loss for three years, and I've used minoxidil for four years. If you're planning a child, three questions come up about finasteride: does it harm sperm, can it harm your pregnant partner or the baby to come, and do you need to stop, and if so how long before. The question also reaches pregnancy helplines: at the Canadian Motherisk service, of 188,188 inquiries between 2002 and 2007, 301 (0.16 percent) were about whether the father was taking any medication, and among these, finasteride was among the most commonly asked-about drugs, alongside methotrexate, prednisone and azathioprine.1

The answer is different for the 1 mg tablet, the 5 mg tablet, dutasteride, and the scalp spray, so I'll cover each separately, together with the regulatory documents, which also differ from each other. I wrote about the basics of finasteride and dutasteride, how they work and their side effects, in the parent article.

At a daily 1 mg dose, no change was measured in semen in healthy young men compared with placebo; a mild, partly transient decrease was measured at the 5 mg dose and with dutasteride. The trials look at four things. Semen volume is the amount of fluid released with one ejaculation, in millilitres. Sperm concentration tells you how many sperm are in one millilitre, and total sperm count tells you how many there are in total in one ejaculation, meaning concentration times volume. This is why total sperm count can drop even if concentration doesn't change: if there's less semen. Motility is the sperm's ability to move, morphology is their shape.

Daily 1 mg, the dose authorised for hair loss. Overstreet and colleagues in 1999 randomised 181 healthy men aged 19 to 41 to daily 1 mg finasteride or placebo, double-blind, for 48 weeks, and a subgroup of 79 of them provided semen samples regularly. Finasteride didn't significantly change sperm concentration, total sperm count, motility or shape. Semen volume dropped by 0.3 ml (11 percent) in those on finasteride, and by 0.2 ml (8 percent) in those on placebo, with no significant difference between the two groups. The authors' conclusion is that the 48-week treatment didn't affect sperm production.2 The limitation is that this is about healthy, non-infertile men, and the abstract doesn't report semen data from the 60-week period after treatment; I didn't have access to the full text. The original product's (Propecia) UK summary of product characteristics states that in its three 12-month, placebo-controlled trials (945 men got Propecia, 934 got placebo), decreased semen volume was reported as a side effect by 0.8 percent of those on Propecia and 0.4 percent of those on placebo. The document also mentions a separate trial in which the effect on semen volume didn't differ from placebo.3 The US document cites the exact same figure pair from a 48-week trial (0.3 ml and 11 percent, versus 0.2 ml and 8 percent),4 so this is likely the same trial, not a separate confirmation.

Daily 5 mg, the dose for benign prostate enlargement, five times the hair-loss dose. Amory and colleagues in 2007 studied 99 healthy men for a year: 34 got daily 5 mg finasteride, 33 got daily 0.5 mg dutasteride, 32 got placebo. Total sperm count dropped significantly from baseline at week 26, by 34.3 percent with finasteride and 28.6 percent with dutasteride. At week 52 (the drop was 16.2 percent with finasteride and 24.9 percent with dutasteride) and 24 weeks after the end of treatment (6.2 and 23.3 percent), the difference was no longer significant for either. Motility dropped by 6–12 percent with both drugs, both during treatment and at follow-up, neither changed shape. The authors describe this as a mild decrease that appears reversible after stopping.5 These percentages are relative to baseline, not adjusted against placebo.

Quintero and colleagues' 2026 review links finasteride to a 34 percent and dutasteride to a 29 percent drop in sperm count.6 The abstract doesn't name which trial these numbers come from. Rounded, they match the Amory trial's week-26 values (34.3 and 28.6 percent), so my own conclusion is that they most likely come from there; if so, this is the 5 mg dose's transient value, which was no longer significant by week 52, and doesn't apply to the 1 mg dose. For the 1 mg dose, the placebo-controlled data is the Overstreet trial's.

The 5 mg tablet's US label also describes a 24-week trial in healthy volunteers: median semen volume dropped by 0.6 ml (22.1 percent), and total sperm count per ejaculation dropped along with it. Concentration, motility, shape and pH didn't change in a clinically meaningful way. Values stayed within the normal range, and returned to baseline after stopping the drug, over an average of 84 weeks.7 The document doesn't give the sample size or the control group.

Daily 0.5 mg dutasteride. According to the 2025 regulatory communication agreed with the EMA, dutasteride is indicated for the symptomatic treatment of benign prostatic enlargement; hair loss isn't among its indications.8 Avodart's UK summary of product characteristics describes healthy volunteers aged 18 to 52 (27 got dutasteride, 23 got placebo), with 52 weeks of treatment and 24 weeks of follow-up. At week 52, adjusted against placebo, total sperm count dropped by 23 percent, semen volume by 26 percent, motility by 18 percent, concentration and shape didn't change. 24 weeks after treatment, total sperm count was still 23 percent below baseline. Average values stayed within the normal range throughout, and didn't reach the pre-defined clinically meaningful change of 30 percent, but two men had a sperm-count drop of more than 90 percent by week 52, with partial improvement at follow-up. The document states that the possibility of reduced male fertility can't be excluded.9 The US document phrases it as: the effect on total sperm count hadn't reversed after 24 weeks of follow-up.10

The document doesn't name which trial this is. Based on the dose, the 52-week treatment, the 24-week follow-up and the healthy volunteers, it's likely the same trial that Amory and colleagues reported against baseline, just adjusted against placebo here, so I'm not counting the two sets of figures as two separate confirmations. Jebli and colleagues' 2026 systematic review (a descriptive summary of 184 trials, without a meta-analysis) focused on newer trials providing good- or high-quality evidence of harmful effects of certain agents on male hormones or fertility, and names dutasteride among them; I didn't have access to the full text, so I can't see which trials this rests on.11

Finasteride spray applied to the scalp. I found no trial on sperm or fertility, and the spray's summary of product characteristics states that its effect on human fertility hasn't been studied.12 This is covered in a separate section below.

What to take from this: if you read a sperm figure, check which dose, which week, and against what it's measured. For the 1 mg dose, no difference was measured against placebo in healthy men; the mild decrease was measured at the 5 mg dose and with dutasteride, and for dutasteride, the documents say total sperm count hadn't returned to baseline even after 24 weeks of follow-up.

Large improvement, without a control group, has been described in men attending fertility clinics who were taking finasteride, after stopping it. Oligospermia means there's little sperm in the semen, azoospermia means there's none at all.

Samplaski and colleagues in 2013 reviewed a Toronto male-infertility clinic's database from 2008 to 2012. Of the 4,400 people seen, 27 (0.6 percent) were on finasteride, at an average of 1.04 mg daily, for an average of 57.4 months. After stopping the drug, sperm count rose an average of 11.6-fold. Of those whose concentration was below 5 million/ml, 57 percent rose above 15 million/ml. Sperm count didn't drop in any of the men, and hormone levels, motility and shape didn't change. The authors' conclusion is that finasteride can reduce sperm count in some men even at a low dose, should be stopped in men with reduced fertility and low sperm counts, and should be used cautiously by anyone wanting a child.13 This was a before-after comparison, without a control group, in a group already being seen for infertility, and the abstract doesn't say how long after stopping the re-measurement happened. Without a control, it also can't be separated how much of the improvement is due to stopping the drug, because a re-measurement after a very poor result can also come out better by chance. My own reading is that the average 11.6-fold multiplier is strongly pulled up by the very low starting cases, so it doesn't follow from this that a healthy man's sperm count would drop to a tenth because of finasteride.

The case reports point the same way. Liu and colleagues in 2008 (the same Toronto group) described two men taking 1 mg daily for hair loss. One had azoospermia measured for more than a year, and was scheduled for a testicular tissue sample (biopsy); six months after stopping finasteride, his concentration was 5.5 million/ml. The other went from 4 million/ml to 6.6 million/ml after 3 months, and to 18.7 million/ml after 6 months.14 Chiba and colleagues in 2011 described a man who had low sperm counts measured five years earlier, and became azoospermic after a year on daily 1 mg finasteride; after stopping, his semen volume increased immediately, and 16 weeks later his concentration rose above 10 million/ml. The authors say that in men with pre-existing impaired sperm production like this, the drug may worsen it further.15

Tu and Zini in 2011 described a 48-year-old man with normal sperm values but a high DNA fragmentation index (how fragmented the sperm's DNA is), who was on a low dose of finasteride. His fragmentation index was 30 percent a year earlier, and still the same when re-measured two months later; after stopping, it was 21 percent at 3 months, and 16.5 percent at 3 more months. No child had been born by the time of publication, and the authors only hypothesise the cause and effect.16 Collodel and colleagues in 2007 examined three young men at a fertility centre who had been on finasteride for five years. A year after stopping, sperm production recovered, motility and shape improved, but the proportion of sperm with an abnormal chromosome count (double chromosome set, or an extra sex chromosome) stayed high. The paper doesn't report a pre-treatment measurement, so the cause can't be judged.17 Ricci and colleagues in 2012 described a man who had been on finasteride for roughly 10 years: 3 months after stopping, he had a severely low sperm count measured, a month later concentration had improved, the following month his partner conceived spontaneously, and a healthy child was born at term.18 These are case reports of one to three people, without a control.

Drobnis and Nangia's 2017 review says the low doses used for hair loss have been studied by fewer trials, and these showed little effect in men with normal sperm quality, but a negative effect on sperm count in men with low sperm counts.19 Propecia's UK label states there's no long-term fertility data, no trial targeted men with reduced fertility, and men planning a child were initially excluded from the clinical trials. Spontaneous reports of infertility and poor semen quality have come in since it went to market, some with another risk factor present, and improvement or normalisation of semen quality was reported after stopping the drug. In the side-effect table, the frequency of infertility is listed as “not known.”3

Finasteride also shows up in side-effect reports. Tan and colleagues' 2025 analysis found that in the US FDA's adverse-event database, between 2004 and 2023, finasteride was the most frequently named drug among reports of decreased semen quality (845 cases), dutasteride was second (163).20 Gong and colleagues in 2026 found 45 reports in the same US database where improvement came after stopping finasteride, and 5 where the complaint returned after restarting. Their abstract calls this strong evidence for a causal link; in the discussion, they say the same thing supports a causal link, but can't be conclusively settled from spontaneous reports, needs confirmation by a well-designed clinical trial, and the number of such reports is small.21 These are voluntary reports, and it isn't known how many people were taking the drug at the time, so they don't measure frequency; the authors also note that for a well-known drug, media attention can inflate the proportion of reports.

Ask your doctor this if you've had a poor semen result before, or you've been trying for a while: is it warranted for me to stop finasteride, and should I have a semen test before and after? For men with low sperm counts and reduced fertility, the Samplaski group recommends stopping.

There's no trial on whether finasteride or dutasteride affects the chance of conception. Sperm values are an indirect sign; how many months it takes a couple to reach pregnancy hasn't been measured for either drug. Drobnis and Nangia described this gap in 2017,19 and my own search found no such trial since. That pregnancy can still occur while on the drug is shown indirectly by the documents: Propecia's UK label describes pregnancies where the woman was exposed to the drug through the semen of a man taking finasteride.3

I looked at three urology guidelines. The American urology and reproductive medicine societies' (AUA/ASRM) male infertility guideline (2020, amended 2024) sees an effect from only finasteride among the listed drugs: reduced semen volume, which appears dose-dependent. It rates the evidence as low quality, and gives no recommendation on stopping or timing.22 The Canadian Urological Association's 2023 azoospermia guideline lists 5-alpha-reductase inhibitors (which includes finasteride and dutasteride) among the drugs that should be asked about during work-up.23 In the European Association of Urology's (EAU) online male infertility chapter, as of September 2026, I couldn't find either finasteride or dutasteride mentioned.24

A hair-specialist author group, Trüeb and colleagues, recommend in 2022 that when prescribing finasteride, at least men uncertain about their fertility, but in their view perhaps all of them, should be seen by an andrologist (a specialist in male fertility) before starting. Anyone who finds this awkward can start with an at-home sperm-count test instead, but in an uncertain case this doesn't replace a full andrological work-up. In their view, oral finasteride should be suspended in cases of reduced fertility.25 This is the authors' own recommendation, not a professional society's guideline.

What to take from this: none of the guidelines I reviewed give a number for when to stop; the expert suggestion is a semen test when starting finasteride, at least for anyone uncertain about their fertility, in the authors' view perhaps for everyone starting finasteride.

None of the guidelines and package leaflets I reviewed generally require stopping before trying to conceive, and none give a timeframe. Samplaski and colleagues say that men with reduced fertility and low sperm counts should stop finasteride, and that men who want to have a child should use it with caution; Trüeb and colleagues likewise recommend suspending it in cases of reduced fertility.1325 If you and your doctor decide to stop, three building blocks help with the timing: how long it takes the drug to clear the blood, how long it takes to make a sperm, and when improvement showed up in the case reports.

The half-life is the time it takes for the amount in the blood to fall by half. For finasteride in men aged 18 to 60 it's about 5–6 hours, and about 8 hours over age 70,3 so it clears the blood quickly. Dutasteride's is measured in weeks: about 3–5 weeks according to the UK label,9 and detectable in the blood for 4–6 months after stopping according to the US label.10

Spermatogenesis is sperm production: the process from starting cells in the testis to a finished sperm. Heller and Clermont's classic 1963 estimate puts this at about 64 days.26 Misell and colleagues measured it in 2006 in 11 men with normal sperm concentration: they had the men drink heavy water (water labelled with the heavier form of hydrogen) for three weeks, and the labelled sperm appeared in the semen after an average of 64 ± 8 days (42–76 days).27 Amann's 2008 review says the accepted value could be off by as much as 6 days, because the 1960s data isn't precise enough.28

In the case reports, improvement showed up over months. In Liu and colleagues' two cases it was after 3 and 6 months,14 in Chiba and colleagues' case after 16 weeks,15 in Tu and Zini's case after 3, then another 3 months.16 At the 5 mg dose, semen volume returned to baseline after an average of 84 weeks,7 and with dutasteride, total sperm count was still 23 percent below baseline 24 weeks after treatment.9

There's one recent study on dutasteride that also looked at how long it had been taken, with serious limitations. Kim and colleagues in 2025 split 200 applicants (aged 28 to 39) at a Korean fertility centre into five groups of 40, based on how long they'd been taking 0.5 mg dutasteride daily for hair loss beforehand (under 6 months, 6–12, 13–18, 19–24, or over 24 months), then re-tested them 6 months after stopping. The longer they'd taken it, the smaller the semen volume and motility. Motility and volume increased in every group after stopping, but in the two longest-use groups the improvement in motility wasn't significant, and in the longest group neither was the improvement in volume (p = 0.076). The authors calculated thresholds of 17.8 and 20.3 months for the persisting difference.29 There was no group that hadn't taken dutasteride at all, everyone also got a lifestyle programme alongside stopping (limits on caffeine, alcohol and smoking, sleep, fluids, exercise), there are internal inconsistencies in their tables, and a letter to the editor names body mass index as a possible confounder.30 So the 17.8 and 20.3 months are an assumption, and can't be used as a safety cutoff.

My own reading of this, which isn't a guideline and isn't a measurement: finasteride clears the blood quickly, but making a sperm takes about two months on average (42 to 76 days in the Misell measurement), and in the case reports on men with reduced fertility, improvement showed up over 3–6 months. Dutasteride itself stays detectable in the blood for months; I couldn't find a measurement of how long it stays in semen after stopping.

Stopping has a cost on the hair side too: the Propecia UK label says the benefit starts to reverse within six months, and returns to baseline within 9–12 months.3 Ask your doctor this: given my medication and my semen results, is stopping even warranted, and if so, how far ahead of trying?

All three oral drugs are contraindicated in women who are pregnant or who could become pregnant, because they may interfere with the development of a male fetus's external genitalia; whether condoms are needed because of the man's semen is answered differently by each label. The Propecia UK label's reason is that these drugs inhibit the conversion of testosterone to DHT in certain tissues, and if given to a pregnant woman may cause abnormalities of a male fetus's external genitalia (the penis and scrotum).3 The labels for 5 mg finasteride and for dutasteride also contraindicate them for women who are pregnant or could become pregnant.319

The tablet and the capsule. An intact finasteride tablet is coated, and under normal handling this can be touched. A broken or crushed tablet, however, must not be handled by a woman who is pregnant or could become pregnant, because the active substance may be absorbed, and this could pose a risk to a male fetus.3 If contact does happen, the US label says the affected skin area should be washed immediately with soap and water.4 The two labels differ for the dutasteride capsule. The UK label says dutasteride is absorbed through the skin, so women, children and adolescents should avoid contact with leaking capsules, and the skin should be washed immediately with soap and water after contact.9 The US label is stricter: a woman who is pregnant or could become pregnant should not handle the Avodart capsule at all, and if she does come into contact with a leaking capsule, the affected skin should be washed immediately with soap and water.10

How much of the drug ends up in semen? A nanogram (ng) is a billionth of a gram. At 1 mg daily, finasteride was undetectable after six weeks in 60 percent (21 of 35) of 35 men's semen samples, with an average of 0.26 and a highest measured value of 1.52 ng/ml. The US label works from the worst case: the highest value, 5 ml of semen daily, and complete vaginal absorption would expose a woman to at most 7.6 ng a day, which is 650 times less than the 5 micrograms (5000 ng) that, in men, didn't change blood DHT levels.4 The Propecia UK label says less than 0.001 percent of the 1 mg dose reaches the semen per ejaculation, and based on studies in rhesus monkeys this amount is unlikely to pose a risk to a male fetus: in pregnant monkeys, a daily intravenous dose of 800 ng given throughout embryonic and fetal development caused no abnormalities in male fetuses, which is at least 750 times the largest estimated exposure via semen.3

At 5 mg daily, finasteride in the semen of 69 healthy men ranged from undetectable up to 10.54 ng/ml after 6–24 weeks, and up to 21 ng/ml in an older, less sensitive measurement in 16 men; the US label estimates this as 50–100 times less than the 5 micrograms mentioned above.7 The Proscar UK label says it isn't known whether a pregnant woman's contact with the semen of a man taking 5 mg would harm a male fetus; in pregnant rhesus monkeys, the same daily intravenous dose of 800 ng, about 60–120 times the estimated amount from the semen of a man taking 5 mg, caused no abnormalities in male fetuses.31

At 0.5 mg dutasteride daily, semen in 26 men averaged 3.4 ng/ml (0.4–14) after 12 months, which is on average 11.5 percent of the serum level. The US label estimates, for a 50 kg woman with 5 ml of semen and complete absorption, a blood level of about 0.0175 ng/ml, which is about 100 times less than the level that caused abnormalities of the male genitals in animal studies, and more than 96 percent of the dutasteride in semen is protein-bound, which may reduce the amount available for vaginal absorption. In the study in pregnant monkeys, the external genitalia of male offspring weren't feminised; at the highest dose tested, however, fetal adrenal gland and prostate weight were lower, and ovary and testis weight were higher. The label calculates these doses, based on the worst case (the highest measured semen concentration and complete absorption), as up to 16 times the greatest possible exposure to a woman, or 32–186 times when scaled to body weight.10 The Avodart UK label says it isn't known whether dutasteride received via semen would harm a male fetus; if it does, the risk is greatest in the first 16 weeks of pregnancy. Based on the monkey data, the label considers this unlikely, and recommends a condom regardless if the partner is pregnant or could become pregnant.9

The condom question, by product:

The sources for the table are the UK labels for Propecia,3 Proscar31 and Avodart,9 plus the Hungarian Summary of Product Characteristics for Fynzur,12 and on the US side the three FDA labels4710 and the FDA's 2025 communication.32 I haven't seen the Hungarian or another EU Summary of Product Characteristics for 1 mg finasteride, so I quote the UK text there.

There's little data on births. The Propecia UK label reports that among post-marketing reports of women exposed via semen during pregnancy, data came in on 8 live-born boys, and in one report received after the fact, the infant had simple hypospadias (where the urethral opening isn't at the tip of the penis). According to the label, cause and effect can't be judged from this, and hypospadias is relatively common, occurring in 0.8–8 of every 1000 live-born boys. A further 9 boys were born after semen exposure in clinical trials, with no abnormalities reported for them.3 That's 8, plus a further 9, live-born boys, which is too few to rule out a rare abnormality.

Zeng and colleagues in 2025 reviewed 3210 reports of paternal exposure out of 16,180,533 reports in the FDA's adverse event database from 2010 to 2022, and the pairing of finasteride with cryptorchidism (where the testis doesn't descend into the scrotum) gave a disproportionate reporting signal, based on 11 reports.34 A reporting ratio measures how much more often a drug and a symptom appear together in reports than for other drugs; it doesn't measure risk, because it isn't known how many fathers took the drug. The authors say the signal is indirect but warrants suspicion, and that the reports can be biased. I couldn't find a follow-up study that tracked thousands of fathers' drug use through to a birth (a cohort or registry study) for finasteride or dutasteride.

What you can take from this: the condom question depends on which product you're taking. The UK labels don't call for a condom with 1 mg finasteride, call for reducing contact with semen at 5 mg, and recommend a condom with dutasteride. Keep the broken tablet and the dutasteride capsule (the intact one too, per the US label) away from your pregnant or potentially pregnant partner.

Possibly, but there's no measurement of it: the spray's label states that its effect on human fertility hasn't been studied.12 The idea follows from the fact that blood finasteride levels are much lower, and DHT falls less as well; for a pregnant partner, though, the spray carries its own risk through skin contact. Finasteride sprayed onto the scalp is sold in Hungary as Fynzur, and in several EU countries as Finjuve, and it's a prescription-only medicine. It occurred to me too that when trying to conceive, the spray might be the more manageable route. These three facts together give the picture.

The first fact: fertility hasn't been studied. I couldn't find a study of the spray on sperm, semen or conception, nor a measurement of finasteride in semen after using the spray. The label states that because the average peak blood finasteride level after the spray is more than a hundred times lower than with the 1 mg tablet, it's “unlikely” that the active substance reaches the semen.12 That's the label's conclusion, with no measurement behind it.

The second fact: the blood level is lower, and DHT falls less. Piraccini and colleagues in 2022 randomly assigned 458 men aged 18 to 40 to the spray (189), placebo (184) or a 1 mg daily tablet (85), double-blind, for 24 weeks, at 45 European centres, including 6 in Hungary. At week 24, the highest finasteride blood level averaged 48.0 picograms/ml with the spray and 5029 picograms/ml with the tablet (a picogram is a thousandth of a nanogram). Blood DHT fell 34.5 percent from baseline with the spray and 55.6 percent with the tablet, and didn't change in the placebo group.35 The spray's label states that among those whose DHT was in the normal range at baseline, it fell below the normal range in 15.3 percent with the spray and 55.2 percent with the tablet, and both decreases were clinically significant.12 The authors say this doesn't rule out DHT-related, whole-body side effects for either form, but they're less likely with the spray.35 There was no fertility endpoint in this study.

The third fact: the spray carries its own risk for a pregnant partner. The label states that a woman who is pregnant or could become pregnant must not come into contact with the spray, with the treated scalp, or with surfaces the spray has touched, because the finasteride may be absorbed and could pose a risk to a male fetus; after accidental contact, the affected area should be washed thoroughly. The treated scalp shouldn't touch a pillow, helmet or hat until dry, and the spray must be left on the scalp for at least 6 hours.12 Beyond the prohibition for pregnant women, the label gives no time limit. An English-language hair loss blog (Perfect Hair Health), in a 2025 update, writes of roughly 30 minutes of drying time and the same period of physical contact to avoid,36 which is milder than the official label. The label's own estimate is that at the highest recommended daily dose, the treated man's blood level is a 39th part of the exposure calculated as having no adverse effect in pregnant rhesus monkeys, and estimates the partner's as even lower;12 the prohibition still applies regardless. With the tablet, this precaution doesn't apply: the intact tablet can be handled, and the rule on semen differs by product.

The spray and the tablet also differ in another area. The EMA's 2025 review confirmed that suicidal ideation can occur with oral 1 mg finasteride, at an unknown frequency. 325 such cases were identified in the EU adverse event database, 313 with finasteride and 13 with dutasteride (one case reported both), against an estimated roughly 270 million and 82 million patient-years of use respectively (a patient-year is one person's use for one year). For the spray, the authority says there isn't enough evidence for a causal link, so the spray's label hasn't changed.837 I've covered this in detail for the tablet in the parent article, and for the spray in the article on topical finasteride.

My own reading: “could be gentler” is a conclusion drawn from the lower blood level and the smaller DHT reduction, with no fertility measurement behind it. During pregnancy, though, the spray adds a new task, keeping the treated scalp, the pillow, the hat and your hand away from your partner, which the tablet doesn't require. Ask your prescribing doctor this if you'd switch to the spray: does it have an advantage over the tablet for me during family planning, and how do we manage skin contact if my partner becomes pregnant?

There's no human fertility study on minoxidil; there's animal research and one adverse-event reporting signal. The label for oral minoxidil (Loniten) states that there's no human fertility data; in male and female rats, conception rates fell in a dose-dependent way, at one to five times the highest dose used for human blood pressure treatment.38 The low-dose oral minoxidil used for hair loss is off-label, and I haven't separately looked into this. The label for the 5 percent topical solution (Regaine) also reports only rat data: conception and implantation rates fell at doses of at least 8 times the human exposure given orally, and at least 25 times given subcutaneously.39

Santana and colleagues' 2023 systematic review gathered 31 cell and rodent studies. The authors say both drugs acted as endocrine disruptors, causing oxidative stress (an excess of oxygen-derived molecules that damage cells) and structural changes mainly in the testis, and that finasteride may be more harmful to male reproductive health.40 This isn't human data. The Propecia UK label states that animal studies showed no relevant adverse effect on fertility (I wrote above about the post-marketing infertility reports),3 and the Santana paper also notes there's no consensus that minoxidil impairs male fertility. Gong and colleagues' 2026 analysis found an infertility signal for minoxidil too, alongside finasteride and dutasteride, in adverse-event reports; the authors stress this is a reporting signal, without frequency or causation, and the abstract doesn't split out the topical and oral forms.41 Neither the 1 mg tablet's nor the spray's label reports data on using finasteride together with topical minoxidil.312

I haven't looked into whether minoxidil on a man's scalp affects a pregnant partner through touch, so I won't write about that here. What you can take from this: there's no human fertility study on minoxidil, only animal research and one reporting signal, so if you're planning a child, put this to your doctor alongside finasteride.

The reason for the blood-donation wait is the same as with a pregnant partner: the blood drawn from you could be given to a pregnant woman. The US Avodart label says not to donate blood for at least 6 months after dutasteride, so that a pregnant woman doesn't receive dutasteride through a transfusion.10 I didn't find a blood-donation warning in the UK labels for Avodart or Propecia, so your own country's blood service's rule governs.

The answers depend on your product, your semen test results and your situation, so it's worth writing these down before you see your prescribing doctor, or an andrologist if you also want your sperm checked:

• Which product am I taking exactly (1 mg or 5 mg finasteride, dutasteride, or the spray), and what does its label say about semen and a pregnant partner?
• Do I need a semen test now, while taking the drug, and if I stop, when is it worth repeating?
• Is stopping before trying to conceive even warranted for me, and if so, how far ahead?
• What will happen to my hair in the meantime, and when can I start again?
• If I switched to the spray, would it have an advantage for me during family planning, and how do we manage skin contact if my partner becomes pregnant?
• What should I do about minoxidil and the other things I use on my hair?