Bicalutamide

Bicalutamide is a medication licensed as an antiandrogen therapy for prostate cancer. It belongs to the class of drugs known as nonsteroidal antiandrogens. Bicalutamide works by blocking androgen receptors, which prevents the action of androgens such as testosterone and dihydrotestosterone (DHT). These hormones can stimulate the growth of prostate cancer cells.

The mechanism of action of bicalutamide involves competitive inhibition at the androgen receptor. By binding to these receptors, it blocks the interaction of androgens with their target receptors on prostate cancer cells, which reduces the growth-stimulating effect of androgens on those cells. Its US label dose is 50 mg a day, taken with another hormone treatment for advanced prostate cancer.

Because it blocks androgens, bicalutamide has also been explored off-label in other androgen-related conditions, such as female pattern hair loss (FPHL) and hirsutism. In FPHL, androgens can lead to miniaturization of hair follicles and hair thinning; the reasoning is that blocking the receptor might slow this. Whether it does so has not been shown in a controlled trial.

The evidence for hair loss is limited. It consists mainly of retrospective case series and a small pilot study in women. The one randomised, double-blind trial (Libório et al., JAAD International 2025, 74 women) found that adding bicalutamide 25 mg a day to oral minoxidil gave no additional improvement at 24 weeks. No study has reported long-term outcomes.

Bicalutamide carries important safety warnings. Its US label warns that severe liver injury, including fatal liver failure, has been reported, usually in the first three to four months, and it requires liver blood tests before starting, regularly for the first four months, and periodically after that. The label states that bicalutamide has no indication for women and should not be used in them, and that it is contraindicated in pregnancy because it can harm a developing fetus. The label also lists breast pain and breast enlargement, sensitivity to sunlight, rare lung inflammation (interstitial lung disease), and an interaction with warfarin-type blood thinners. Its use for hair loss is off-label and needs a prescriber who monitors liver function.

In the community, discussions about bicalutamide often compare it with other antiandrogens such as spironolactone, and share personal experiences. Some users report improvement or better tolerability than spironolactone; others raise liver risk, pregnancy risk and the difficulty of finding a prescriber. These are individual accounts, not trial results.

In summary, bicalutamide is a prostate-cancer medicine that some dermatologists prescribe off-label for women with androgen-related hair loss. The published evidence is limited, the one randomised trial was negative, and the drug carries label warnings about liver injury, use in women and pregnancy.

References: Libório RDS, Motta AVD, Miot HA, Müller Ramos P. Bicalutamide 25 mg combined with minoxidil 1 mg versus minoxidil 1 mg for female pattern hair loss: a randomized double-blind clinical trial. JAAD Int. 2025;19:48–55. PMID 40034971. CASODEX (bicalutamide) US prescribing information, DailyMed: https://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=dfee4fe7-8478-4a3e-925d-00be3cd0ab67