This can become red and irritated and cause pain when they urinate. The tell-tale sign is a moist/wet underwear. The treatment is to pat dry and "dab" the area after urinating. If your daughter has had fevers or previous urinary tract infections then getting a urine culture may also be needed.
Elias Milgram, MD
Painful urination, increased frequency urination, urgency of urination, with or without lower abdominal pain, with or without fever usually need to be investigated to rule out urinary tract infection. Please see your doctor asap to evaluate.