Hair loss common after COVID-19 infection

There appears to be an increased risk of hair loss – a phenomenon called telogen effluvium – after COVID-19 infection.

Hair loss was one of a wide range of symptoms patients complained to their primary care physicians following COVID-19, said Dr Brian Abittan, director of skin and hair rejuvenation at Mount Sinai Health System in New York, US. “A day doesn’t go by that I don’t get asked about hair loss following COVID-19 infection.”

A not-so-recent study supported Abittan’s observation in the clinic, demonstrating that 22 percent of patients hospitalized for COVID-19 had experienced hair loss, which typically happens after stress, a shock, or a traumatic event. [Lancet 2021;397:220-232]

Another study showed that patients who had a COVID-19 infection were nearly four times as likely to have hair loss (hazard ratio [HR], 3.99) compared with those who were not infected. [Nat Med 2022;doi.org/10.1038/s41591-022-w]

 Hair shedding could last 6 months

“Hair could start shedding 2 or 3 months after infection and could last for up to 6 months,” said Dr Alexis Young, a dermatologist at Hackensack University Medical Center in Hackensack, New Jersey, US. “It typically takes about a year and a half for hair to grow back.”

She said the heightened inflammation in COVID-19 patients could be behind the hair loss. Patients who were hospitalized with COVID or been placed on a mechanical ventilator may experience more shedding than those with mild cases, she added.

On average, people shed about 100 to 150 hair strands a day during the exogen phase, said Dr Powell Perng, a dermatologist and specialist in hair loss at the University of Utah Health in Salt Lake City, Utah, US.

Other inducers of hair loss

But when an individual experiences a stressful event, such as COVID-19 infection, interleukin release increases which can prematurely shift a significant proportion of growing anagen hairs into a resting telogen state.

“Instead of the 10 percent of hairs that are in the resting and shedding phase, up to 50 percent of hairs are resting and shedding, which is more than normal,” added Perng.

Young added that more research is warranted to determine what causes severe hair shedding following COVID-19 infection. Other theories point to the direct invasion of the virus into the hair follicles which could interrupt the growth cycle or the micro clots typical in COVID cases that could be interfering with the same growth cycle.

Evaluate your patients

The presence of autoimmune thyroid disease also puts patients at greater risk for hair loss, hence clinicians should carefully evaluate patients for targeted treatment, Abittan advised. If hair loss is COVID-related, simple hair care will help to grow back the hair, he added.