In the US, superficial folliculitis is quite common, although the exact incidence is unknown. Medical attention is often sought for recurrent or deep forms of folliculitis.
Superficial folliculitis occurs in both sexes and all races.
It tends to affect adults more frequently than children. This is likely due to adults having more terminal hair growth.
Certain subtypes of folliculitis tend to affect particular populations more often than others. Herpes folliculitis occurs predominantly in the beard region in men, whereas Malassezia folliculitis has a slight female predominance.[8]Faergemann J. Pityrosporum infections. J Am Acad Dermatol. 1994 Sep;31(3 Pt 2):S18-20.
http://www.ncbi.nlm.nih.gov/pubmed/8077501?tool=bestpractice.com
Hot-tub folliculitis occurs more commonly in people who use spa facilities. Pseudofolliculitis barbae commonly affects men of African descent.[9]Halder RM. Pseudofolliculitis barbae and related disorders. Dermatol Clin. 1988 Jul;6(3):407-12.
http://www.ncbi.nlm.nih.gov/pubmed/3048823?tool=bestpractice.com
The prevalence in this population is reported to be between 45% and 83%.[10]Alexander AM, Delph WI. Pseudofolliculitis barbae in the military: a medical, administrative and social problem. J Natl Med Assoc. 1974 Nov;66(6):459-64;479.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2609333
http://www.ncbi.nlm.nih.gov/pubmed/4436875?tool=bestpractice.com
Eosinophilic pustular folliculitis tends to affect adults with an average age of 30, with a male to female ratio of 5:1.[11]Ota T, Hata A, Tanikawa A, et al. Eosinophilic pustular folliculitis (Ofuji's disease): indomethacin as a first choice of treatment. Clin Exp Dermatol. 2001 Mar;26(2):179-81.
http://www.ncbi.nlm.nih.gov/pubmed/11298111?tool=bestpractice.com
HIV-associated eosinophilic folliculitis is seen in patients with HIV, usually with a low CD4+ count <300 cells/mm³.[2]Majors MJ, Berger TG, Blauvelt A, et al. HIV-related eosinophilic folliculitis: a panel discussion. Semin Cutan Med Surg. 1997 Sep;16(3):219-23.
http://www.ncbi.nlm.nih.gov/pubmed/9300633?tool=bestpractice.com
A limited number of cases of eosinophilic pustular folliculitis have been observed in infants less than 1 year of age, with a male predominance.[12]Porriño-Bustamante ML, Sánchez-López J, Aneiros-Fernández J, et al. Recurrent pustules on an infant's scalp with neonatal onset. Int J Dermatol. 2016 May;55(5):505-8.
http://www.ncbi.nlm.nih.gov/pubmed/26266955?tool=bestpractice.com
[13]Hernández-Martín Á, Nuño-González A, Colmenero I, et al. Eosinophilic pustular folliculitis of infancy: a series of 15 cases and review of the literature. J Am Acad Dermatol. 2013 Jan;68(1):150-5.
http://www.ncbi.nlm.nih.gov/pubmed/22819356?tool=bestpractice.com