There are a variety of drugs that can change the timing, duration, frequency, and/or intensity of menses. Patients may present with amenorrhea or with new-onset abnormal uterine bleeding (AUB). Medications that may be the culprit fall into the following categories.

Hormones – Birth control initiation, use, and cessation can all cause irregular bleeding, a change in cycles (timing, quality, and/or intensity), and/or amenorrhea. Each type of birth control has a range of potential menstrual outcomes with use.

Steroids – Anabolic steroids may cause irregular menses, while corticosteroids may cause intermenstrual bleeding or delayed cycles.

Anticoagulation medications – Warfarin and aspirin may increase the flow and intensity of bleeding. They may contribute to intermenstrual bleeding as well.

NSAIDs – Ibuprofen and naproxen can be used to decrease menstrual flow at time of menses.

Thyroid medications – Having thyroid levels that are out of range can change menstrual patterns to be heavier or lighter or more irregular.

Antipsychotics – Due to increased prolactin, patients may experience irregular menses or amenorrhea.

Antiepileptic medications – These medications can cause irregular menses or amenorrhea. Hepatic enzyme-inducing antiepileptic drugs such as phenobarbital, phenytoin, and carbamazepine increase serum sex hormone-binding globulin (SHBG) concentrations and, over time, lead to diminished bioactivity estradiol, which may result in menstrual disorders. Valproic acid may affect androgen concentrations and reduce serum follicle-stimulating hormone levels, resulting in polycystic changes to the ovaries, high serum testosterone levels, and menstrual disorders.

Chemotherapy – It is not unusual for patients undergoing chemotherapy to become amenorrheic. This can be a short-term side effect or could be permanent depending on the drugs used, the location of the chemotherapy, and the duration of treatment. In some cases, menses continue and may be heavier in the setting of chemotherapy-induced thrombocytopenia. See menopause for discussion of induced menopause.

Drugs of abuse – Heroin will often cause amenorrhea. Methadone maintenance tends to help normalize periods. Cocaine can cause irregular menses.

Related topic: primary ovarian insufficiency