Alopecia is common in people with severe COVID-19 who spend time in ICU and experience acute hypoxic respiratory failure, dermatologists in Europe have reported.

In a single centre study of 38 patients, Italian clinicians found that  70% of COVID-19 survivors who received prolonged respiratory support developed telogen effluvium (TE) alopecia within three months of hospital discharge.

They described TE alopecia a scalp disorder characterised by excessive shedding and thinning of hair, usually associated with drugs, trauma and emotional and physiological stress.

Reporting their results in the Internal Medicine Journal, the researchers noted that the COVID-19 survivors presenting with TE would have been influenced by alopecia-promoting factors such as being on anticoagulants during hospitalisation, having infection-related disruption of the androgen-regulated pathway and experiencing emotional distress due to the severity of the disease’s clinical manifestations.

“However, the most important pathophysiologic pathway that might have predisposed patients to TE onset may be found in the prolonged persistent severe hypoxia these patients experienced, which may be responsible for a lower or insufficient blood supply to the scalp tissues, leading to TE alopecia,” they wrote.

“Furthermore, the use of tight mask head support for many consecutive hours or sometimes days, may have also contributed to the drop in scalp oxygenation and the normal vital cycle of hair,” they added.

The study authors said that previous studies had suggested up to a third of patients may develop alopecia after ICU admission, and there had been other anecdotal reports of alopecia being common among patients hospitalised for COVID-19 disease.

“Further studies will be warranted to clarify better each of those hypothesised mechanisms or the potential correlations among them,” they suggested.