One study showed that spironolactone or the steroidal antiandrogen cyproterone acetate both in combination with a birth control pill had equivalent effectiveness for hirsutism. Spironolactone is considered to be a first-line treatment for hirsutism, finasteride and the steroidal antiandrogen cyproterone acetate are considered to be second-line treatments, and flutamide is no longer recommended for hirsutism due to liver toxicity concerns. The nonsteroidal antiandrogen bicalutamide is an alternative option to flutamide with improved safety.The combination of spironolactone with a birth control pill in the treatment of acne appears to have similar effectiveness to a birth control pill alone and the combination of a birth control pill with cyproterone acetate, flutamide, or finasteride. However, this was based on low- to very-low-quality evidence. Spironolactone may be more effective than birth control pills in the treatment of acne, and the combination of spironolactone with a birth control pill may have greater effectiveness for acne than either alone. In addition, some clinical research has found that flutamide is more effective than spironolactone in the treatment of acne. In one study, flutamide decreased acne scores by 80% within 3 months, whereas spironolactone decreased symptoms by only 40% in the same time period. However, the use of flutamide for acne is limited by its liver toxicity. Bicalutamide is a potential alternative to flutamide for acne as well.
Spironolactone bodies are eosinophilic, round, concentrically laminated cytoplasmic inclusions surrounded by clear halos in preparations stained with hematoxylin and eosin. Pregnancy and breastfeeding
In the United States, spironolactone is considered pregnancy category C meaning that it is unclear if it is safe for use during pregnancy. It is able to cross the placenta. Likewise, it has been found to be present in the breast milk of lactating mothers and, while the effects of spironolactone or its metabolites have not been extensively studied in breastfeeding infants, it is generally recommended that women also not take the medication while nursing. However, only very small amounts of spironolactone and its metabolite canrenone enter breast milk, and the amount received by an infant during breastfeeding (<0.5% of the mothers dose) is considered to be insignificant.A study found that spironolactone was not associated with teratogenicity in the offspring of rats. Because it is an antiandrogen, however, spironolactone could theoretically have the potential to cause feminization of male fetuses at sufficient doses. In accordance, a subsequent study found that partial feminization of the genitalia occurred in the male offspring of rats that received doses of spironolactone that were five times higher than those normally used in humans (200 mg/kg per day). Another study found permanent, dose-related reproductive tract abnormalities rat offspring of both sexes at lower doses (50 to 100 mg/kg per day).In practice however, although experience is limited, spironolactone has never been reported to cause observable feminization or any other congenital defects in humans.