Hair Loss, Fever and the Spanish Flu

Studies from 1919 Indicated 102.5 F (39.2 C) as an important Cut Off

Telogen effluvium refers to a form of hair loss whereby the patient experiences more shedding than they would consider their normal daily rate. There are hundreds of triggers including stress, low iron, thyroid problems, weight loss/dieting and medications.Fever is a trigger of telogen effluvium, especially in children. However fever can cause hair loss in adults too.

We learned alot about the relationship between fever and hair loss in the Spanish Flu Pandemic in 1918-1919.
In 1919, H.H. Hazen reported in the Journal of the American Medical Association 50 people with hair shedding after the flu. 47 were women. For 90 % of these individuals, a fever above 102.5 F (39.2 C) was felt to be the trigger. The hair shedding started about 9 weeks after the fever started. All patients experienced rapid regrowth of hair. For over 100 years, this study has remained a frequently referenced study about the cut off for fever that is most likely to be associated with telogen effluvium in adults.

Reference

Hazen H.H. JAMA 1919; 77:1452