Medications That Cause Hair Loss

Hair loss can have various causes, some of which are treatable while others are permanent, with physical or genetic origins. Baldness is only partially treatable for many patients, while some unfortunate individuals may have to accept it as a permanent condition.

Medications are one environmental cause of hair loss, meaning that the effects usually diminish relatively soon after stopping the specific medication.

Although medications that trigger hair loss are used to treat a variety of conditions, the hair loss they cause typically occurs in one of two ways.

The hair growth cycle has three phases: anagen, catagen, and telogen. The first phase can last up to six years, during which the hair is actively growing. In the second phase, the lower part of the hair follicle shrinks, pushing the hair root outward. The last phase, telogen, is a "resting" phase for the hair that lasts three to four months, after which the hair falls out.

When taking medications that may cause hair loss as a side effect, hair can fall out in one of two ways, either during the telogen or the anagen phase.

The first and most common type is called telogen effluvium. This occurs approximately two to four months after starting the medication and causes hairs that are usually in the growth phase to prematurely enter the catagen phase and fall out. Typically, one can lose between 100 to 150 hairs per day (normal loss ranges from about 50 to 100 hairs), with gradual shedding.

The second type, anagen effluvium, occurs within days or weeks after beginning treatment. Here, hair does not fall out in the telogen phase but rather directly in the anagen phase. The active ingredients in medications disrupt the division of stem cells that produce new hair or halt this process altogether. Hair loss in such cases is more severe, and hair may be lost across the entire scalp, including eyebrows, eyelashes, or even body hair. The best-known medications with this side effect are cytostatics – drugs that inhibit cell growth and division, most commonly used in cancer treatment (chemotherapy).

However, hair loss is not only caused by cytostatics; it can also be an unpleasant side effect of various other medications, such as those for treating high blood pressure, gout, arthritis, heart disease, blood clotting disorders, antidepressants, cholesterol-lowering drugs, medications containing high doses of vitamin A (such as acne treatments), amphetamines, hormonal supplements, and more.

Treatment for hair loss caused by specific medications is straightforward – simply stopping the medication. In most cases, hair grows back within a few months, much like after chemotherapy. If this does not happen, which is rare, it is best to consult your doctor, who may prescribe anti-hair-loss medications, such as Propecia for men or Aldactone for women.