Finasteride, dutasteride and trying to conceive: what applies when your partner is pregnant?

If your partner is pregnant or wants to become pregnant and you take a DHT blocker for hereditary hair loss, one question above all determines how to proceed: who is taking the medication?

The clear-cut side first. A woman who is pregnant or could become pregnant must not take 5-alpha-reductase inhibitors such as finasteride and dutasteride. This applies without exception. For you as the man being treated, the picture is more nuanced, and it depends on which product you take and in what form. In most cases it is less dramatic than many fear. Even so, you should not stop or switch anything on your own, but always together with your doctor. Why these medications matter at all, what applies to the tablet and the spray, and how the two of you decide together, is explained here.

Why caution applies to DHT blockers during pregnancy at all

Finasteride and dutasteride lower the level of the hormone dihydrotestosterone (DHT). That is exactly what is wanted in hereditary hair loss, because DHT causes the sensitive hair follicles to shrink. How this connection works is explained in the article DHT and hair loss.

But DHT has another role as well: in the womb it is needed for the normal development of the external genitalia of a male fetus. If the DHT level is lowered at the wrong moment, this development can be disrupted, for example in the form of a malformation of the urethra.¹ Only male fetuses are affected, not female ones. The risk is greatest in the first 16 weeks of pregnancy, when the genitalia are forming.² This is the heart of the whole discussion about caution, and that is why it is worth keeping the individual situations clearly apart.

When the woman herself is being treated: a clear no

For women who are pregnant or could become pregnant, all 5-alpha-reductase inhibitors are contraindicated. This applies to finasteride and dutasteride, as a tablet and as a spray. The reason is precisely the disruption of the genital development of a male fetus just described.¹ That is why these active ingredients are, as a matter of principle, not used against hair loss in women of childbearing age.

This is not a question of amount or timing, but an absolute contraindication. A woman trying to conceive does not take these medications, not even briefly or at a low dose.

If you take finasteride as a tablet

Finasteride tablet: barely any passes into the semen, usually no need to stop. Finasteride passes into the semen only in very small amounts. At the usual 1 mg dose it was not detectable at all in around 60 percent of the samples examined, and the highest value ever measured was tiny. Even this maximum value lies, with a very large safety margin, below the amount that would have a hormonal effect on the partner. Compared with the dose that had any effect on a fetus in animal studies, the margin is larger again by many times over.³ For this reason, the prescribing information does not require stopping in order to protect a male fetus. The advisory service MotherToBaby also concludes that use by the father is not expected to increase the risk of malformation.⁴

In practice this means: a man taking finasteride tablets can, as a rule, conceive a child and also continue taking it during the pregnancy. Whether this applies to your situation is decided by your doctor. Some recommend a condom as a precaution during an existing pregnancy. Based on the data this is not necessary, but it does no harm either if it gives you a more reassured feeling. What other side effects finasteride can have is explained in the article Finasteride and its side effects.

If you take dutasteride

Dutasteride: more potent and longer-lasting, hence stricter precautionary rules. Dutasteride belongs to the same class of active ingredients and likewise passes into the semen only in a small amount, which is also strongly bound to protein. Here too, the calculated exposure of the partner is well below critical levels.⁵ Even so, dutasteride is deliberately regulated more cautiously, and there are two reasons for this.

First, it acts more strongly. It inhibits both types of 5-alpha-reductase and lowers the DHT level more comprehensively than finasteride. Second, it stays in the body for a very long time: its half-life is several weeks, and the active ingredient is still detectable in the blood months after the last dose. From this stronger and longer-lasting effect follows a specific precaution. The European prescribing information explicitly recommends using a condom during a pregnancy or when the partner could be pregnant.² The US prescribing information does not contain this recommendation; we follow the more cautious European line here. The long time in the body also means that men taking dutasteride should not donate blood for up to six months after the last dose.²

What applies to the finasteride spray?

Finasteride spray: less active ingredient in the body, but an honest gap in the data. With the spray, considerably less active ingredient reaches the body than with the tablet. The DHT level in the blood does fall measurably, but less strongly than with oral use.⁶ This suggests that less also passes into the semen, but this has not been measured.

For topical finasteride there is a gap in the data here: no published measurements of the active ingredient in the semen exist. The risk via this route therefore cannot be quantified as precisely as with the tablet. By calculation it should be below the tablet's already very low value, but this is not firmly established.

With the spray, a different point is more important, namely protecting your partner from direct contact. A pregnant partner or a woman trying to conceive should not come into contact with the spray itself, with the freshly treated scalp or with sprayed surfaces. Let the product dry after applying it and wash your hands before close contact occurs.

What your partner should keep in mind when handling tablets and spray

Regardless of how much active ingredient passes over via the semen, there is one route that is easy to avoid: direct absorption through the skin. A few rules are enough for this.

• Finasteride film-coated tablets: Intact tablets are safe to handle. Broken or crushed tablets, on the other hand, should not be handled by pregnant women or women trying to conceive, because the active ingredient can then be absorbed through the skin.³
• Dutasteride soft capsules: Here the rule is stricter. Pregnant or possibly pregnant women should not handle the capsules at all. If contact with a leaking capsule does occur, the affected area should be washed with soap and water.⁵
• Spray and treated scalp: Avoid contact with the product, the freshly sprayed scalp and sprayed surfaces until everything has dried and hands have been washed.

These are simple everyday precautions, not exceptional measures. They apply only to pregnant women and women trying to conceive.

Can finasteride make conception more difficult?

Sometimes it is not a pregnancy that is at issue, but rather that trying to conceive is not yet working. Then the question arises whether the medication itself affects fertility.

With finasteride at the 1 mg dose, a meaningful effect on the number, motility or shape of sperm has not been established. The ejaculate volume can decrease somewhat. There are isolated reports of worsened semen quality, which improved again after stopping.⁷ Dutasteride intervenes more strongly: on average it lowers the total sperm count, the ejaculate volume and the motility. In studies, these values mostly remained within the normal range. The total sperm count in particular had not yet fully recovered after around half a year of follow-up; the effects are considered partly reversible.⁵

If you are trying for a child and it is not working, a pause from the medication can be a sensible step. Whether, when and for how long is decided by the doctor together with you. Do not stop a DHT-blocking medication for this without consulting a doctor.

How the two of you decide this together with the doctor

Let us summarise the situations, because they give a rough framework that the doctor confirms or adjusts for your case:

• Finasteride as a tablet: based on the data usually able to be continued, condom optional as an additional precaution.
• Dutasteride: to be handled more cautiously, with a condom recommendation in Europe and a long lead time when stopping because of the long time in the body.
• Spray: little systemic exposure, but make sure to protect your partner from direct contact.

In any case: this is an individual medical decision that depends on the product, the form, the pregnancy status and your situation regarding trying to conceive.

With us, you complete an online medical health questionnaire for this, our doctors review your information, and if a medication-based therapy is suitable for you, they discuss the right approach with you. Trying to conceive or a pregnancy of your partner belongs explicitly in this conversation, so that the choice of medication fits accordingly. A prescription is never guaranteed, and if you wish, a German partner pharmacy handles the dispensing, while you remain free to choose your own pharmacy. How the process works in detail is explained under Start treatment.