Tinea capitis is a fungal infection of the hair follicles of the scalp and is more common in prepubertal children than in adolescents or adults. It is typically caused by fungal species of the genera Trichophyton and Microsporum. Infection can be passed between members of a family, especially on fomites such as hairbrushes and pillows, and some species can be acquired from household pets. Clinically, tinea capitis takes both inflammatory and noninflammatory forms. The noninflammatory form consists of patches of localized scaly alopecia, which are often itchy, with an annular appearance. Ringworm may also be present on the body. The inflammatory form manifests as scattered pustules, abscesses, or a kerion (a boggy, inflamed swelling of the scalp, often painful or pruritic). Lymphadenopathy, especially occipital, is common. Tinea capitis is sometimes accompanied by an id (dermatophytid) reaction, especially after trauma to the affected skin or after the initiation of treatment. An id reaction is a systemic immune-mediated response to a localized dermatitis, and presents as a symmetric, pruritic, fine papulovesicular rash, although it can sometimes mimic a drug eruption. Fungal studies of the id lesions will be negative, and the rash resolves with effective treatment of the primary infection.