MGA can cause hypogonadism and associated symptoms like diminished secondary sexual characteristics, sexual dysfunction, osteoporosis, and reversible infertility in men and premenopausal women. Combining MGA with an androgen/anabolic steroid like oxandrolone, nandrolone decanoate, or testosterone in men can alleviate MGA-associated symptoms of hypoandrogenism as well as further increase appetite and weight gain. Less common but more serious side effects of MGA include cardiovascular/thromboembolic complications such as thrombophlebitis. It may also cause glucocorticoid side effects such as Cushing syndrome-like symptoms, steroid diabetes, and adrenal insufficiency at high dosages. Case reports of deep vein thrombosis, pulmonary embolism, jaundice, intrahepatic cholestasis, and meningiomas in association with high-dosage MGA have been published. In older patients who take MGA, one in 23 will have an adverse event leading to death. Overdose
MGA has been studied at very high dosages of as much as 1,600 mg/day with no serious adverse effects observed. No clear increase in rate or severity of side effects have been observed up to 1,600 mg/day MGA except for weight gain, mild increases in blood pressure, and some fluid retention. In post-marketing experience, limited reports of overdose have been received. Signs and symptoms described in these reports have included diarrhea, nausea, abdominal pain, shortness of breath, cough, unsteady gait, listlessness, and chest pain. There is no specific antidote for overdose of MGA. Treatment should be supportive and based on symptoms. MGA has not been assessed for dialyzability. However, due to its low solubility, it is thought that dialysis would not be useful for treating MGA overdose.
Megestrol acetate (MGA), sold under the brand name Megace among others, is a progestin medication which is used mainly as an appetite stimulant to treat wasting syndromes such as cachexia. It is also used to treat breast cancer and endometrial cancer, and has been used in birth control. MGA is generally formulated alone, although it has been combined with estrogens in birth control formulations. It is usually taken by mouth.Side effects of MGA include increased appetite, weight gain, vaginal bleeding, nausea, edema, low sex hormone levels, sexual dysfunction, osteoporosis, cardiovascular complications, glucocorticoid effects, and others. MGA is a progestin, or a synthetic progestogen, and hence is an agonist of the progesterone receptor, the biological target of progestogens like progesterone. It has weak partial androgenic activity, weak glucocorticoid activity, and no other important hormonal activity. Due to its progestogenic activity, MGA has antigonadotropic effects. The mechanism of action of the appetite stimulant effects of MGA is unknown.MGA was discovered in 1959 and was introduced for medical use, specifically in birth control pills, in 1963. It may be considered a "first-generation" progestin. The medication was withdrawn in some countries in 1970 due to concerns about mammary toxicity observed in dogs, but this turned out not to apply to humans. MGA was approved for the treatment of endometrial cancer in 1971 and wasting syndromes in 1993. It is marketed widely throughout the world.