Telogen effluvium in the new SARS-CoV-2 era.

Dear Editor,

SARS‐CoV‐2 infection is well known to produce various dermatologic manifestations, including affection of skin and hair. Telogen effluvium (TE) is one of the most common forms of hair loss, especially in women. It is a nonscarring alopecia characterized by an abnormal shift in the follicular cycle with diffuse synchronization and shedding of telogen hairs, usually involving less than 50% of the hair. , The transit of >20% of the hairs to telogen phase is considered to be diagnostic. The hair fall is sometimes dramatic, causing significant psychological implications in the patients, which worsens the hair condition. It can be divided into acute or chronic when it continues for more than 6 months. Different triggering factors have been described, including drug induced (heparin, vitamin A, antidepressants), nutritional or micronutrient deficiency (vitamin D, B12, iron), autoimmunity, postpartum, infection, trauma, physical or emotional stress, or febrile states. TE usually occurs 2–4 months after the triggering event and resolves 6–12 months after the elimination of the activating factor.

During the last months, the SARS‐CoV‐2 emergency has forced countries to impose mobility restrictions which contribute to negative psychological effects (emotional exhaustion, anger or irritability, and anxiety). These psychological reactions cause release of specific neurotransmitters, neuropeptides, and hormones that promote changes in the hair growth cycle, stimulating the transition of hair from anagen to telogen phase. As a consequence, a higher number of patients with TE have been seen in dermatology consultations. Rivetti et al. reported a worsening in patients previously diagnosed with TE. Also an association of TE after COVID‐19 infection has been reported. , Rizzetto et al. described the first case series of TE related to post‐severe SARS‐CoV‐2 infection.

The diagnosis of TE is usually made clinically. Dermatologic examination shows diffuse loss of hair volume, without defined alopecic patches and a positive pull test. Sometimes patients report a reduction in the diameter of the ponytail or diffuse temporal alopecia. Trichodynia is a common symptom. Trichoscopy is nonspecific, follicular units of only one hair can be found, with no anisotrichosis or loss of follicular units. A trichogram can also help in the diagnosis, and it is considered when more than 20% of hairs are in telogen phase. Another tool for confirming the diagnosis is the wash or Rebora’s test or the modified wash test, in which the patient abstains from showering their hair for 5 days, after which they are invited to shampoo their hair in a basin whose bottom is covered by a filter napkin and to count all the lost hairs.

The therapeutic approach in TE involves the identification of the triggering factor and its elimination. In the case of post‐COVID infection, the triggering factor has been resolved but different possible causes should be considered including use of drugs, or if unsure of autoimmune diseases or nutritional deficiencies, laboratory tests should be done. , When the cause has been studied and the patient has been reassured the lost hair will grow back, corticosteroid creams, topical minoxidil, or oral minoxidil (chronic TE) can be given. Some authors also consider using sulfur amino acids, vitamin B complex, or topical peptides.

Dermatologists should be aware of the association of COVID‐19 and confinement stress to hair loss for TE. Also, they should be capable of discarding other causes and explaining the benign nature of this disease. It would be interesting to describe the severity of the TE in relation to the severity of fever, drugs utilized, and the time of hospitalization in case of COVID‐19 infection. Further studies including a greater number of patients are warranted in order to explain the association and etiopathogenesis of TE and SARS‐CoV‐2.

Ethics approval

All procedures followed were in accordance with ethical standards and with the Helsinki declaration.