脂溢性皮炎很常见,正常人群的发病率在1%-2%。[3]Gupta AK, Madzia SE, Batra R. Etiology and management of seborrheic dermatitis. Dermatology (Basel). 2004;208:89-93.http://www.ncbi.nlm.nih.gov/pubmed/15056994?tool=bestpractice.com 在校正年龄和性别后的一项调查中发现,在男孩中的发病率为10%,女孩中为9.5%。[4]Foley P, Zuo Y, Plunkett A, et al. The frequency of common skin conditions in preschool-aged children in Australia: seborrheic dermatitis and pityriasis capitis (cradle cap). Arch Dermatol. 2003;139:318-322.http://www.ncbi.nlm.nih.gov/pubmed/12622623?tool=bestpractice.com 发病最高的时期是在出生的前3个月,随后发病率急剧下降直至1岁,接下来的4年里发病率缓慢下降。[4]Foley P, Zuo Y, Plunkett A, et al. The frequency of common skin conditions in preschool-aged children in Australia: seborrheic dermatitis and pityriasis capitis (cradle cap). Arch Dermatol. 2003;139:318-322.http://www.ncbi.nlm.nih.gov/pubmed/12622623?tool=bestpractice.com 大多数人有极轻度到轻度的脂溢性皮炎。 头皮糠疹也被称为乳痂,在1116名受试儿童中的发病率为42%,其中86%的儿童只表现为极轻度到轻度的类型。[4]Foley P, Zuo Y, Plunkett A, et al. The frequency of common skin conditions in preschool-aged children in Australia: seborrheic dermatitis and pityriasis capitis (cradle cap). Arch Dermatol. 2003;139:318-322.http://www.ncbi.nlm.nih.gov/pubmed/12622623?tool=bestpractice.com 老年人的发病率高于普通人群。[5]Mastrolonardo M, Diaferio A, Vendemiale G, et al. Seborrhoeic dermatitis in the elderly: inferences on the possible role of disability and loss of self-sufficiency. Acta Derm Venereol. 2004;84:285-287.http://www.ncbi.nlm.nih.gov/pubmed/15339072?tool=bestpractice.com