Seasonality of hair shedding in healthy women complaining of hair loss

Dermatology. 2009;219(2):105-10. doi: 10.1159/000216832. Epub 2009 Apr 29.


Background: A number of otherwise healthy women with or without clinical alopecia complain of recurrent hair loss, presumably reflecting seasonality in the growth and shedding of hair.

Objective: To test the hypothesis that periodicity in hair shedding reflects seasonal changes in human hair growth.

Methods: Retrospective case study over a period of 6 years of apparently healthy women with the complaint of hair loss. All underwent biochemical investigations, and trichograms were made.

Results: After exclusion of patients with a disease or on drugs known to cause hair loss, 823 women remained. Analysis of trichograms demonstrated annual periodicity in the growth and shedding of hair, manifested by a maximal proportion of telogen hairs in summer. A second peak seems to exist, though it is less pronounced, in spring. The telogen rates were lowest in late winter.

Conclusions: These results confirm the findings of former authors who have indicated seasonal changes in human hair growth, though this is the first study performed systematically in a representative number of women.

MeSH terms

  • Adolescent
  • Adult
  • Age Distribution
  • Aged
  • Alopecia / diagnosis*
  • Alopecia / epidemiology
  • Cohort Studies
  • Female
  • Hair / growth & development*
  • Humans
  • Incidence
  • Middle Aged
  • Probability
  • Prognosis
  • Retrospective Studies
  • Seasons*
  • Severity of Illness Index
  • Young Adult