Redness and swelling at the root of pubic hair may be caused by folliculitis, local irritation or allergic factors. 1. Folliculitis: mainly due to bacterial infection caused by a kind of inflammatory reaction, the early manifestation of local redness, swelling and pain, and in severe cases, may even cause generalized fever symptoms, with the progress of the disease, there may be the formation of abscesses. 2. Local irritation: it may be caused by wearing too tight underwear or excessive friction during sex, which may also lead to local skin breakage and redness. 3. Allergic factors: If the perineum is allergic to certain substances, such as underwear or sanitary napkins, it is also easy to cause allergic phenomenon, resulting in redness and swelling of the pubic area. Redness and swelling at the root of the pubic hair may also be caused by other reasons, it is recommended to go to the hospital in time to find out the cause and then targeted treatment.