What Happens If You Take Spironolactone While Pregnant?

Spironolactone is not recommended during pregnancy, primarily because of its ability to block the action of androgens. In animal studies, the drug has caused feminization of male offspring, and while human evidence remains limited, the theoretical risk to a male fetus’s genital development is enough that prescribing guidelines strongly advise against its use in pregnant women. The reality, though, is more nuanced than a blanket warning suggests, and many women who take spironolactone for acne, hormonal symptoms, or blood pressure find themselves wondering what actually happens if they are exposed before realizing they are pregnant.

Why Spironolactone Raises Concerns During Pregnancy

Spironolactone was originally developed as a potassium-sparing diuretic and is widely prescribed to treat high blood pressure, heart failure, and conditions involving excess aldosterone. But it also has a well-known secondary effect: it blocks androgen receptors and interferes with enzymes that produce androgens. That anti-androgen activity is actually the reason many women take it in the first place, because it can reduce hormonal acne, slow unwanted hair growth, and help manage symptoms of polycystic ovary syndrome.

The same anti-androgen property that makes spironolactone useful for skin and hair issues is what creates concern during pregnancy. Androgens, including testosterone and its more potent form dihydrotestosterone, play a critical role during fetal development. In a male fetus, androgens drive the formation of external genitalia. Spironolactone competes with dihydrotestosterone for binding at androgen receptors and also inhibits some of the enzymes involved in making androgens, which in theory could interfere with that process.¹ The specific worry is undervirilization, meaning incomplete masculinization of a male infant’s genitalia.²

What Animal Studies Show

Much of the alarm around spironolactone in pregnancy comes from animal research rather than human cases. When pregnant rats are given anti-androgenic compounds, including spironolactone, during the critical window of fetal sexual differentiation, male offspring can develop malformations of the reproductive tract. These studies consistently show that disrupting androgen signaling during development produces physical changes in male pups, though the exact pattern of effects depends on the specific drug and its mechanism of action.³

The rat data is fairly clear: high-dose anti-androgens during a specific developmental window can feminize male offspring. But translating animal findings directly to humans is always tricky. Rats metabolize drugs differently, the doses used in research tend to be proportionally much higher than human therapeutic doses, and the timing of sexual differentiation relative to drug exposure does not map perfectly between species. Still, because the stakes involve irreversible developmental changes, the animal data is enough to warrant serious caution even without abundant human evidence.

The Gap in Human Evidence

Here is where the picture gets genuinely frustrating for anyone trying to assess real-world risk: human data on spironolactone exposure during pregnancy remain scarce and largely inconclusive.¹ There are no randomized controlled trials, and for obvious ethical reasons there never will be. What exists in the medical literature is a handful of case reports, which describe individual women who were exposed accidentally or before they knew they were pregnant.

The most detailed published case involves a 25-year-old woman who received spironolactone at a relatively high dose of 240 mg per day for one week during her second trimester due to a pharmacy dispensing error. She was 16 weeks pregnant at the time. Despite the exposure, she went on to deliver a healthy male infant at 38 weeks with completely normal genitalia, and follow-up showed the child was developing normally.¹ That single case is reassuring, but it is also just one case. A week of exposure at 16 weeks might carry a different risk profile than months of exposure starting in the first trimester, or exposure at a different dose, or exposure during the narrow window when male genital formation is most sensitive to androgen disruption.

The scarcity of data is partly a product of how spironolactone is prescribed. The women most likely to be taking it are those with acne, hirsutism, or PCOS, and prescribers typically emphasize reliable contraception as a requirement before starting the drug. That means accidental pregnancies on spironolactone are relatively uncommon, which is good for patients but leaves the medical literature thin on outcomes.

The FDA Category and What It Actually Means

Spironolactone carried an FDA pregnancy category of C before the agency phased out that letter-grading system in 2015.² Category C meant that animal studies had shown an adverse effect on the fetus, but there were no adequate studies in humans, and the drug might be justified in certain situations if the potential benefit outweighed the potential risk. In practice, though, the anti-androgen concern has led most guidelines to treat spironolactone as effectively contraindicated during pregnancy, particularly when safer alternatives exist.

The old letter categories are worth understanding because you will still see them referenced on drug information sheets and in older medical literature. Category C was a broad and somewhat unhelpful bucket: it covered everything from drugs with alarming animal data to drugs with almost no data at all. The label told you the evidence was incomplete, but it did not tell you how dangerous the drug actually was. For spironolactone, the specific concern about genital development in male fetuses makes the warning more targeted than a generic “insufficient data” classification might suggest.

Does the Risk Apply Only to Male Fetuses?

Virtually all of the concern centers on male fetuses. Androgens are the hormones that drive masculinization of external genitalia during fetal development, and spironolactone’s mechanism blocks that process. For a female fetus, the anti-androgen effects of spironolactone would not be expected to cause the same type of developmental disruption, because female genital development does not depend on androgen signaling in the same way.

That said, the absence of expected harm is not the same as proof of safety. Female fetuses are exposed to the same maternal blood levels of the drug, and androgens do play some roles in female development as well, particularly later in life. But the published concern in medical literature is specifically about undervirilization of males, and that is where the warnings are focused. If you were exposed to spironolactone early in pregnancy and are carrying a female fetus, the theoretical risk profile is substantially lower, though your doctor will still want to monitor the pregnancy closely because the evidence base is thin in all directions.

Common Scenarios Where Accidental Exposure Happens

Most cases of spironolactone exposure during pregnancy fall into a few predictable patterns. The most common is a woman taking the drug for acne or hirsutism who becomes pregnant before her next prescription review. Many dermatologists prescribe spironolactone as a long-term treatment for hormonal acne in women, and although the standard practice is to pair it with reliable contraception, no method is perfect. A missed pill, a broken condom, or a change in plans about pregnancy can result in early first-trimester exposure before a positive pregnancy test.

A less common but notable scenario involves women with primary aldosteronism, a condition where the adrenal glands produce too much aldosterone, leading to high blood pressure and low potassium. Spironolactone is a first-line treatment for this condition, and some women with primary aldosteronism may not realize they need to switch medications before conceiving. The case report of accidental exposure described above involved a pharmacy error, which is rarer still but illustrates that medication mix-ups can happen even when no one intended to prescribe the drug during pregnancy.

What to Do If You Were Exposed

If you discover you are pregnant and have been taking spironolactone, the first step is to stop taking it and contact your healthcare provider. The drug should be discontinued as soon as pregnancy is confirmed. Beyond that, the approach depends on how long the exposure lasted, the dose, and how far along the pregnancy was when exposure occurred.

The critical window for male genital development is roughly between weeks 8 and 14 of gestation. Exposure before that window, or after genital formation is already complete, carries a lower theoretical risk. Exposure during that window at higher doses would be the scenario of greatest concern. Your provider will likely recommend a detailed anatomy ultrasound to assess fetal development, and in some cases may refer you to a maternal-fetal medicine specialist for additional monitoring.

The published case of accidental exposure at 16 weeks resulted in a normal outcome, which is consistent with the idea that the timing and duration of exposure matter.¹ But “reassuring single case report” is not the same as “proven safe,” and your doctor will rightly treat the situation with care. The honest answer you should expect from a clinician is that the risk is plausible based on the drug’s mechanism but unquantifiable based on available human data.

Safer Alternatives When You Need a Mineralocorticoid Receptor Antagonist

For women who genuinely need a mineralocorticoid receptor antagonist during pregnancy, typically those with primary aldosteronism causing dangerous blood pressure or potassium levels, eplerenone is the preferred alternative. Eplerenone works on the same receptor as spironolactone to block excess aldosterone, but it is far more selective. It does not bind meaningfully to androgen receptors, which eliminates the theoretical risk of feminizing a male fetus.²

Eplerenone carried an FDA pregnancy category of B, which meant that animal studies had not shown a risk but, again, human studies were limited. Clinical guidelines suggest that the first choice for managing blood pressure in pregnant women with primary aldosteronism is standard approved antihypertensive drugs combined with potassium supplementation, but eplerenone appears to be a safe and effective option when a mineralocorticoid receptor antagonist is specifically needed.²

For women who were taking spironolactone specifically for acne or hair growth, the conversation is different. Those are not conditions that require treatment during pregnancy, and most dermatologists will simply discontinue spironolactone and manage skin symptoms with pregnancy-safe topical options. The anti-androgen approach to acne is paused until after delivery and, if applicable, after breastfeeding.

Contraception Requirements While on Spironolactone

Because the risk to a pregnancy is theoretical but plausible, and because spironolactone is so commonly prescribed to women of childbearing age, most prescribing guidelines strongly recommend reliable contraception throughout treatment. Some dermatologists will not prescribe spironolactone without confirming that a patient is using an effective contraceptive method, and a few insist on a pregnancy test before starting the drug.

This is one area where clinical practice varies more than you might expect. Unlike isotretinoin, which has a formalized risk-management program requiring two forms of contraception and monthly pregnancy tests, spironolactone has no such mandated system. The level of contraceptive counseling you receive depends heavily on your prescriber. Some are strict about it, others mention it briefly and move on. If you are prescribed spironolactone and are sexually active with a partner who could get you pregnant, it is worth taking the contraception conversation seriously yourself, even if your prescriber does not emphasize it.

Hormonal contraceptives, including combined oral contraceptive pills, are a common pairing with spironolactone for acne treatment. The pill provides contraception while also contributing its own anti-androgen effects, making the combination particularly effective for hormonal breakouts. An IUD, implant, or other long-acting method also works well for the contraceptive piece, though without the additional hormonal acne benefit of oral contraceptives.

Why the Evidence Will Probably Stay Limited

It is worth understanding why the data gap on spironolactone and pregnancy is unlikely to close anytime soon. Prospective studies, where researchers deliberately expose pregnant women to a potentially harmful drug, are ethically impossible. What researchers rely on instead are case reports, pregnancy registries, and retrospective analyses of medical records. For a drug like spironolactone, where prescribers already counsel against pregnancy and most women discontinue the drug as soon as they learn they are pregnant, the number of exposed pregnancies entering any database is small.

Even when accidental exposures do occur, they are underreported. A woman who takes spironolactone in early pregnancy, stops when she gets a positive test, and has a healthy baby has little incentive to write it up as a case report. The cases that do get published tend to be either concerning outcomes or deliberately documented reassuring ones, which creates a biased sample in the literature. The 2024 case report of the pharmacy dispensing error is notable partly because the authors chose to document a normal outcome, adding one more data point to an extremely thin evidence base.¹

Spironolactone and Breastfeeding

A related question many women have is whether spironolactone is safe while breastfeeding. Spironolactone and its active metabolite canrenone do pass into breast milk in small amounts. Most sources consider the amount transferred to the infant to be low, and many clinicians are comfortable resuming spironolactone during breastfeeding, particularly at lower doses. However, the same anti-androgen mechanism that makes the drug concerning in pregnancy is at least theoretically relevant for a nursing infant, especially a male infant in early life when hormonal signals matter for development.

In practice, many dermatologists will wait until a woman is done breastfeeding before restarting spironolactone, simply because the indication is usually cosmetic and the risk, however small, is not worth taking for acne control. For women who need the drug for blood pressure or aldosteronism, the decision involves weighing the maternal benefit against the small amount of drug the infant receives, and this is a conversation to have with both the prescriber and the pediatrician.

How Spironolactone Compares to Other Anti-Androgens in Pregnancy

Spironolactone is not the only anti-androgen medication that raises pregnancy concerns. Finasteride, used for hair loss and prostate enlargement, works by a different mechanism but carries a similar warning about feminization of male fetuses. Cyproterone acetate, used in some countries for acne and hirsutism, is also contraindicated in pregnancy for the same reason. The through-line is consistent: any drug that substantially blocks androgen activity or production is treated as a risk during pregnancies with male fetuses.

What makes spironolactone somewhat unique is how widely it is prescribed to young women for relatively low-stakes conditions like acne, compared to finasteride, which is predominantly used by men. That means the population most likely to become pregnant while on the drug overlaps heavily with the population taking it. The gap between theoretical risk and real-world evidence is most frustrating exactly in this population, where actual exposures are most likely but published data remains sparse.