This is a MedPage Today story.
Clinicians are seeing an influx of patients experiencing an unsettling side effect after COVID-19: losing their hair.
Dr. Brian Abittan, the director of skin and hair rejuvenation at Mount Sinai Health System in New York, said that he sees multiple patients a week who have reported hair loss after COVID-19.
"A day doesn't go by that I don't get asked about it," Abittan told MedPage Today.
Although more patients are clearly reporting the symptom after COVID, there isn't robust data describing how many patients experience this phenomenon or what factors put someone at risk for it. While there are still many unanswered questions about COVID-related hair loss, experts say the good news is that it appears to be temporary and clinicians should reassure patients that their hair will very likely grow back.
Some evidence has shown that there is an increased risk of hair loss following COVID infection. A study published in Nature Medicine last month found that hair loss was one of a wide range of symptoms that post-COVID patients reported to their primary care physicians.
Patients with a history of COVID were nearly four times as likely to develop hair loss than those who weren't infected, the researchers found.
Additionally, a study in the Lancet journal estimated that 22% of patients who were hospitalized with COVID experienced hair loss after their illness.
The most common type of hair loss seen in post-COVID patients is telogen effluvium.
"The assumption is that COVID-related hair loss is very similar to stress-related hair loss," Abittan said.
Telogen effluvium occurs when the growth cycle of hair is disrupted, induced by traumas such as surgery, illness, or any stressful life event, such as moving or a pregnancy. There are three phases that hair goes through during a growth cycle: anagen, catagen and telogen.
Anagen is the active growth phase, catagen is the transitional phase, and telogen is the resting phase -- in which hair sheds.
Telogen effluvium occurs when a larger proportion of hairs on the scalp shift into this resting phase, resulting in shedding at a higher rate. It's normal for patients to lose about 100 hairs a day, Abittan said.
But with telogen effluvium, patients could lose up to 300, 500, or even 1,000 hairs each day, he added.
"A lot of times people don't even notice that they shed," Abittan said. "But once they shed to a level where they notice, then they start to count every hair on their head."
Hair may start shedding as soon as 2 or 3 months after infection, said Dr. Alexis Young, a dermatologist at Hackensack University Medical Center in New Jersey. That shedding could last for up to six months, and it typically takes about a year and a half for hair to grow back, she added.
There are a few hypotheses about why infection may be causing hair loss in COVID patients, one of which being patients' heightened state of inflammation. Certain inflammatory markers, called interleukins, become elevated during COVID, which could be causing a premature shifting of the hairs into the telogen phase, Young said.
Because telogen effluvium is triggered by stress on the body, it may be that patients who were hospitalized with COVID or placed on a mechanical ventilator experience more shedding than patients with mild cases, she added.
"The more severe cases are probably having more severe hair loss," Young said. However, she added that the causes of hair loss in patients with severe COVID could be multifactorial, linked to the medications they took or the procedures they underwent.
More research is needed to understand what puts a patient at risk of more severe hair shedding, Young stated.
Other theories about what causes COVID-related hair loss include a direct invasion of the virus into the hair follicles, which may interrupt the growth cycle. Given that COVID causes blood clots, some have also raised the hypothesis that tiny microclots may interfere with the growth cycle as well.
Abittan said that to determine the best course of treatment, clinicians should evaluate patients to ensure there are no other underlying causes of hair loss, such as a thyroid issue.
Once COVID-19 is determined as a likely cause of telogen effluvium, there are some oral pills and topical treatments -- none of which are FDA-approved for COVID-linked hair loss -- that patients may turn to. However, gentle combing and hair care practices will be most effective in allowing the hair to grow, Abittan said.
Because telogen effluvium is not a scarring process, hair can -- and likely will -- grow back on its own, Young added. "There's not really anything that can speed that along," she said.
Young advises her patients to eat a healthy diet and try to reduce stress, which could worsen hair loss.
"The majority of people do, ultimately, grow their hair back," Abittan said. "It just takes time."
There's a broad range of symptoms that patients with long COVID can experience, ranging from heart issues to breathing problems and fatigue. Although hair loss may get lost in the mix with some of these other symptoms, Abittan said resolving the issue is important for patients' mental health and well-being.
"When somebody does experience hair loss, it can be quite dramatic, and concerning to the patient," Abittan said. "It definitely can take a toll on people."