Inflammation of the penis. In infancy the condition is usually of the type called ammoniacal balanitis. In such cases the inflammation is due to irritation caused by ammonia produced by the action of bacteria on the urine. Usually it can be prevented by promptly changing wet diapers.

When balanitis occurs in older children and adults, it may be related to sugar in the urine and it may therefore be a warning sign of diabetes mellitus. Other possible causes in adults are an underlying syphilitic sore (chancre) or cancer of the penis.