Skin diseases and allergic reactions 

Intertrigo is inflammation of skin folds from heat, friction and moisture, often worsened by Candida, causing a moist red patch with burning, itching or odour in the groin, armpits, under the breasts or the umbilicus. Keep folds clean and dry, and treat with an imidazole cream plus hydrocortisone for 2–4 weeks.

Pityriasis rosea is a self-limiting rash of children and young adults linked to HHV-6 and HHV-7, starting with a single herald patch followed by smaller scaly lesions in a Christmas-tree pattern. Treat itching with a topical steroid, a short course of prednisolone if severe, and acyclovir.

Melasma is a chronic acquired pigmentation disorder with symmetrical brown patches on the forehead, cheeks, nose, upper lip and chin, more common in women. Treat with strict sun protection, nightly tretinoin for 3–6 months and daily sunscreen, with chemical peels or laser as alternatives.