Post COVID Hair Loss: What We Know and Don’t know

New review Highlights Important Gaps in Knowledge.

Authors from Japan and the US set out to review all articles relating to COVID hair loss from the start of the pandemic up to  November  20,  2021. They used a  total  of  26 articles in their final review,   with  9   observational  studies  and  17 case reports  or series  (total  of  58 cases).

Most  studies  dealt  with  telogen effluvium.  Interestingly, there  were  no  clear  trends  between  COVID-19  severity   and  the  extent  of hair  loss. Most  of the cases of telogen effluvium occurred in females (82.8%), (ie 5:1 ratio F:M). The median  onset of hair  loss of 2.0 months,  and the median  time  to recovery  of hair  loss was 5.0 months  with  a resolution  rate of 95%. The  outcome   of   hair   loss   was   described   only   in   20   cases.   Among   the   20   cases,  19  (95.0%)  had  resolution of hair loss with a medium time to recovery of around 5.0 months months. 5 % that did not have a typical expected recovery and clearly more studies are needed to understand these patients better. The type of hair loss was  predominately   telogen effluvium  (74.1%),  with  the  next  most  common   hair  loss  type  being  early-onset   effluvium   (12.1%).

Key Summary Points:

It’s clear that post COVID hair loss affects women more than men. The reasons are not clear. Although ‘hormones’ are often proposed as the reason for differences in males and females, the reality is that we just don’t know. why females are more susceptible to post covid shedding.

It’s not clear what really causes the hair loss although clearly in early onset effluvium, it’s possible that viral infection of hair follicles could play a role. We would like it if everything made good sense. For example, it would be sensible that patients with lots of hair shedding were the ones who had more severe COVID19 infections. The reality is that’s not true in all studies and this review reminds us of that. Even asymptomatic patients get shedding.

Finally, we really don’t know the long term outcomes of patients who shed. We’d like to think that everything just goes back to normal but the reality is we don’t have that kind of good data. We have data on 20 patients and 5 % seem to not have resolution. Do they need longer before shedding stops? Is it possible some of these patients develop chronic shedding patterns? More studies are needed.

Here are the 5’s We Know So Far:

5 times more  Females affected with Shedding than Males

5 times more Likely Classic TE than Early Onset “Dystrophic” Anagen Effluvium

5 months to Recover

5 % May Not Recover in Expected Manner

5 types of hair loss occur with COVID - telogen effluvium, anagen effluivum, alopecia areata, scarring alopecia and seborrheic dermatitis.

REFERENCE

Czech T et al. Characteristics of Hair Loss after COVID-19: Systematic Scoping Review. J Cosmet Dermatol. 2022 Jul 8.