Hair loss after an infection: why it happens, and how long it lasts

You were sick two months ago, you're feeling much better, and now your hair is falling out in clumps in the shower. This sudden change in timing isn't a coincidence: it's a sign of telogen effluvium, the reactive hair loss that follows a high fever, infection, or shock. Covid-19 brought it to the forefront, but the underlying mechanism has been known for a long time.

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What Covid revealed about the reactive fall

A six-month follow-up study of a large cohort of hospitalized patients in Wuhan, published in The Lancet, reported hair loss in 22% of them. Subsequent data confirmed the phenomenon and clarified its characteristics, notably that the most severe forms of the infection are associated with a higher risk of hair loss.

• It primarily affects women in the published series.
• ELLE occurs after the infection, not during
• It is temporary and does not affect the follicular capital

Why are the fall comes two months later

A high fever and the accompanying inflammation cause a large proportion of the hair to prematurely switch from the growth phase to the resting phase. These hairs remain in place for several weeks before being shed—hence the delay. In post-Covid studies, hair loss appears on average around six to eight weeks after the first symptoms, slightly earlier than in classic telogen effluvium.

Signs of telogen effluvium

You are probably affected if you observe several of these signs:

• A diffuse hair loss, covering the entire head, and not localized to the crown or temples.
• Hair that comes out easily when washed and brushed
• An episode of fever, infection, surgery, or shock two to three months earlier
• An overall loss of density, without any clear depleted areas
• A fall that came on suddenly, in just a few days.

The protocol for restarting regrowth

Telogen effluvium resolves spontaneously within three to six months. The goal is therefore not to stop the hair loss, which will stop on its own, but to support the regrowth: reactivating microcirculation at the root, providing the nutrients necessary for keratin synthesis, and avoiding aggressive procedures during this fragile phase.