Many drugs have been reported to cause hair loss. This loss is usually diffuse, temporary, nonscarring, and limited to the scalp. Women are more commonly affected. The mechanism varies depending upon the causal drug. In most cases, drugs induce the telogen (resting) stage of the hair and may lead to a chronic telogen effluvium. In addition, cytotoxic drugs can cause anagen effluvium, while certain medications (such as anti-tumor necrosis factor-α therapy) can cause alopecia areata. Several medications such as contraceptives containing androgenic progestational agents and topical diclofenac 3% gel could worsen or precipitate androgenetic alopecia.

The degree of anagen effluvium from cytotoxic drugs is dependent upon the dosage, schedule, and route of administration. The risk for alopecia is higher with high-dose, intermittent, intravenous, and/or combination therapies. Topical therapies such as topical timolol solution and topical diclofenac 3% gel can induce hair loss as well. Although drug-induced alopecia is usually reversible upon discontinuation of the culprit medication, permanent alopecia from chemotherapy (taxane and adjuvant hormonal therapy) has been reported. Changes in the hair color, quality, or texture are also possible from chemotherapy.

Localized alopecia has been reported as an adverse effect in men at the site of deoxycholic acid injections for submental adiposity.

See articles on telogen effluvium and anagen effluvium for more information on implicated medications.