Causes of Seborrheic Dermatitis

Sore red rashes may develop in the major flexures of heavily built sportsmen and -women when the weather is hot and damp. These patches are not due to ringworm although they arise at the same sites and are similar in appearance. Some call this condition 'sweat rash' or intertrigo, while others prefer 'seborrhoeic dermatitis'. It is probably due to a combination of mechanical injury from the rubbing of clothes on skin surfaces (the perpetually wet horny layer is weaker than normal) and mild infections (due to overgrowth of the normal skin bacteria). At times it may be very itchy because the inflamed skin develops an eczematous reaction. The clue to distinguishing it from ringworm is that this intertrigo-type rash is symmetrical and reaches up into the apices of the groin.

Stopping all vigorous exercise and staying cool usually clears it up in a day or two. Sometimes a weak, nonirritant antimicrobial cream - such as miconazole (Daktarin, Monistat) - may be required for the more severely affected (see Chapter 28). If there is eczema present as well, a combination of an antimicrobial with hydrocortisone - such as Daktacort - is helpful.