Also, spironolactone is immunosuppressive in the treatment of sarcoidosis.Most of the side effects of spironolactone are dose-dependent. Low-dose spironolactone is generally very well tolerated. Even higher doses of spironolactone, such as 100 mg/day, are well tolerated in most individuals. Dose-dependent side effects of spironolactone include menstrual irregularities, breast tenderness and enlargement, orthostatic hypotension, and hyperkalemia. The side effects of spironolactone are usually mild and rarely result in discontinuation. High potassium levels
Spironolactone can cause hyperkalemia, or high blood potassium levels. Rarely, this can be fatal. Of people with heart disease prescribed typical dosages of spironolactone, 10 to 15% develop some degree of hyperkalemia, and 6% develop severe hyperkalemia. At a higher dosage, a rate of hyperkalemia of 24% has been observed. An abrupt and major increase in the rate of hospitalization due to hyperkalemia from 0.2% to 11% and in the rate of death due to hyperkalemia from 0.3 per 1,000 to 2.0 per 1,000 between early 1994 and late 2001 has been attributed to a parallel rise in the number of prescriptions written for spironolactone upon the publication of the Randomized Aldactone Evaluation Study (RALES) in July 1999. However, another population-based study in Scotland failed to replicate these findings.
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.