Drug-induced Alopecia

Alopecia from drugs is a usually reversible nonscarring diffuse hair loss that occurs within days to weeks of starting a new medication or changing the dose.

There are two types of drug-induced hair loss:
● Anagen effluvium – the shedding of actively growing hairs
● Telogen effluvium – the shedding of resting, or bulb hairs
Anagen effluvium is usually due to chemotherapy drugs and rarely with gold, colchicine or poisoning
with arsenic, bismuth, thallium or boric acid.
Telogen effluvium is the mechanism of virtually all other medication-induced hair loss. The list of possible drug causes is very long and includes:
● Anticoagulants — heparin, warfarin and possibly newer anticoagulants such as rivaroxaban, dabigatran and apixaban
● Antihypertensives — beta-blockers, ACE inhibitors
● hormones — oral contraceptive pill (during/after/changing), hormone replacement therapy,
androgens
● Anticonvulsants — valproic acid 12–28% (dose-dependent), carbamazepine up to 6%, phenytoin
● Mood stabilizers and antidepressants — most, such as lithium 12–19%
● Others — cimetidine, retinoids (acitretin > isotretinoin), antithyroid drugs, cholesterol-lowering
drugs, interferons, anti-infective agents, amphetamines, nonsteroidal anti-inflammatory drugs (NSAIDs), bromocriptine, levodopa, some antipsychotics and anti-anxiety drugs, rarely tricyclic antidepressants such as amitriptyline.
Hair loss due to medications is usually diffuse and non scarring. The hair loss may be ‘patterned’ as seen in male-pattern or androgenetic alopecia or female-pattern alopecia. The scalp is the most common site affected, but all body hair including eyebrows and eyelashes may be lost with chemotherapy.

Management:
Usually, the only treatment required for drug-induced hair loss is to cease the causative drug if it is possible to do so. Once that drug has been ceased, hair shedding settles, although this may take up to 6 months. Evidence of hair regrowth is usually seen within 3–6 months but can take 12–18 months to recover cosmetically.The most effective treatment to reduce hair loss from chemotherapy to date has been cooling the patient’s head to reduce the blood flow around hair follicles. Hair cooling devices are worn for 30 minutes before infusion of the causative drug, during the infusion, and for 90 minutes afterwards.

Written by: Khalid Nagshabandi, medical student

 

Resources:

DermNet