Finasteride Pregnancy & Lactation Safety: What Patients and Partners Must Know

Is finasteride safe to take during pregnancy?

No. Both oral finasteride labels list pregnancy as a contraindication: finasteride use is contraindicated in women when they are or may potentially be pregnant [1][2]. The label gives the reason: finasteride blocks conversion of testosterone to DHT, a hormone the label describes as necessary for normal development of male genitalia, so inhibiting that conversion may cause abnormalities of the external genitalia of a male fetus [1]. The label notes these outcomes resemble those reported in male infants with genetic 5-alpha-reductase deficiency [1].

Propecia, the 1 mg tablet approved in 1997 for male pattern hair loss, is indicated for men only and is not indicated for use in women [3][1]. Proscar, the 5 mg tablet approved in 1992 for symptomatic benign prostatic hyperplasia, carries the same pregnancy contraindication [4][2].

The current Propecia label, effective 14 October 2024, still uses the older letter system in section 8.1, where it states 'Pregnancy Category X' [1].

The label also addresses what happens if the drug is used during pregnancy or a patient becomes pregnant while taking it: the pregnant woman should be apprised of the potential hazard to the male fetus [1].

What about handling tablets?

Propecia and Proscar tablets are coated, and the labels say the coating prevents contact with the active ingredient during normal handling provided the tablets have not been broken or crushed [1][2]. The labels state that women who are pregnant or may be pregnant should not handle crushed or broken tablets [1][2]. If a pregnant woman comes into contact with crushed or broken tablets, the labels direct that the contact area be washed immediately with soap and water [1][2].

That instruction is about contact with a damaged tablet. Swallowing a tablet is a different event — it is the maternal use that the contraindication addresses [1].

Does a partner's finasteride reach the pregnancy?

The label names the route: women could be exposed to finasteride through contact with crushed or broken tablets or through semen from a male partner taking the drug [1]. The quantified semen measurements come from the Proscar (5 mg) label [2].

In two studies of healthy subjects (n=69) taking Proscar 5 mg a day for 6 to 24 weeks, finasteride concentrations in semen ranged from undetectable (less than 0.1 ng/mL) to 10.54 ng/mL, and the highest amount in semen was estimated to be 50- to 100-fold less than the 5 microgram dose that had no effect on circulating DHT levels in men [2].

The label also reports an animal experiment on paternal exposure: no developmental abnormalities were observed in the offspring of untreated female rats mated with finasteride-treated males that received approximately 488 times the recommended human dose, based on AUC [1].

Does finasteride affect male fertility?

The label data come from short semen studies in healthy volunteers, and the 1 mg and 5 mg products report different numbers.

With Proscar 5 mg, 24 weeks of treatment revealed no clinically meaningful effects on sperm concentration, motility, morphology or pH [2]. Median ejaculate volume fell 0.6 mL (22.1%), with a corresponding reduction in total sperm per ejaculate; the values stayed within the normal range and were reversible after the drug was stopped, with an average time to return to baseline of 84 weeks [2].

With Propecia 1 mg, a study in healthy men found a median ejaculate volume decrease of 0.3 mL (-11%) against 0.2 mL (-8%) on placebo after 48 weeks [1].

The Propecia label's postmarketing section also lists male infertility and/or poor seminal quality, and states that normalization or improvement of seminal quality has been reported after discontinuation [1]. The semen changes above are median values from short studies in healthy volunteers, not a prediction for any one man, while the infertility entry is a postmarketing report [1][2].

Is a washout needed before trying to conceive?

We found no study or label statement that sets a waiting period before conception for a man taking finasteride.

Some timing facts are in the label. The mean terminal half-life is about 5 to 6 hours in men aged 18 to 60 and about 8 hours in men over 70 [1]. The enzyme complex itself turns over slowly, roughly 30 days for the Type II enzyme, so the effect on DHT lasts longer than the plasma half-life suggests [1]. Neither figure describes how fast an individual man's semen parameters change, and the Proscar label's own reversibility figure was an average of 84 weeks to return to baseline [2].

What the labels say about breastfeeding

The Proscar label's lactation section says only that Proscar is not indicated for females [2], and the Propecia label says it is not indicated for use in women [1]. The Proscar label gives no data on finasteride in human milk [2].

Is there an approved topical finasteride?

No. No topical or injectable finasteride is FDA-approved; the Drugs@FDA entries for Propecia and Proscar list oral tablets [3][4]. The pregnancy and handling information on this page comes from the oral tablet labels [1][2].