Super-absorbent diapers keep skin dry and have drastically decreased the incidence of diaper rash. However, they have not eliminated it. Urine and stool acting together create an acid environment that breaks down the skin, producing redness and sometimes open sores resembling a burn. When a baby has diarrhea, diaper rash is even more common because of the constant irritation.
Diaper rash occurs because your infant's skin is in contact with urine and stool; therefore, the drier and cleaner you can keep him, the less rashy he should be. To prevent diaper rash, change your baby frequently and wash the area gently with a mild soap such as Dove or Ivory after a bowel movement. Wipes are convenient, especially when you're away from home, but my personal preference is to use soap and water whenever possible. Barrier creams that coat the skin, such as A&D Ointment, Desitin, Triple Paste (my personal favorite), and Balmex can reduce the amount of contact skin has with urine and stool.
If your baby gets a rash, airing his bottom is the best treatment. Leave the diaper off for periods of time and let your baby play in the kitchen or bathroom, where the floor is easy to mop up, or out in the yard. Also use diaper creams liberally. Cortisone cream can help reduce the redness, but don't use it for more than a few days.
Diaper-rash sores can make it easier for yeast (which normally exists on the skin) to penetrate and create an infection. Yeast rashes are particularly common after a baby has taken antibiotics; the medicine changes the skin's normal bacteria balance, allowing yeast to overgrow. The subsequent rash looks dry and red with scaly edges, and each patch is surrounded by separate rashy spots. The good news is that the rash usually looks worse than it feels to your infant. If your pediatrician agrees that your child has a yeast rash, he'll recommend either an over-the-counter antifungal medicine, such as Nystatin or Lotrimin, or a prescription cream to clear it up.
When to Worry:
Severe rashes with open sores that do not heal easily sometimes need to be treated like a burn, using thick applications of prescription burn cream. If baby has large, soft, yellow-fluid-filled blisters, a staph infection may have developed. See your doctor; this needs prompt treatment with oral antibiotics.