Most diaper rashes have nothing to do with formula; however, it is possible. Here is a list of the types of diaper rashes:
Chafing dermatitis. Also known as friction rash, this is the most common form of diaper rash, which makes its mark as redness wherever the diaper rubs against the skin (around the legs, for example, hips, and belly button, in addition to the bum and genitals). Chafing dermatitis is apt to come and go, causing baby little discomfort. It can be easily treated — and sometimes even prevented — with diaper cream, frequent diaper changes, and a looser fitting diaper (consider going up a size if the fit is too tight, and go easy on those tabs, Mom!).
Candidal dermatitis. This tender, deep-red rash is caused by Candida, a yeast-like fungus. (In other words, a yeast infection. And yes, boys can get it too!) It appears in the creases between the abdomen and thigh and can spread from there. Children who are on antibiotics are susceptible to yeast infections, which can be cured with antifungal cream.
Perianal dermatitis: This appears as redness around the anus and is usually caused by alkaline (a high pH factor) in your baby's stools. If your baby is formula-fed and/or has started solids, diet can sometimes be a culprit (this skin condition is uncommon in breast-fed babies). Depending on the severity, treatment can be as simple as a diet change (less fruit, perhaps) coupled with a diaper ointment.
Intertrigo: This type of rash is caused by the rubbing of skin on skin, often at the deep folds between the thigh and lower abdomen. In can sometimes ooze white or yellowish pus, and it may sting when urine touches it (causing your little one to cry each time he or she pees). Generally, a hydrocortisone cream, either prescription or over-the-counter, is the remedy.
Atopic dermatitis: This itchy rash, also known as eczema, often shows up as red scaly patches in other parts of the body first. It can spread to the legs and groin area when a child is between six and 12 months. Causes of infant eczema include allergens, irritants, or hereditary factors. Treatment is usually a hydrocortisone cream.
Seborrheic dermatitis: Better known as cradle cap, this rash can start on the scalp and spread south, or start in the diaper area and spread north. Despite its ugly appearance (deep red, often with yellowish scales), it doesn't appear to cause infants too much discomfort, and generally, cradle cap goes away on its own. Treatment for seborrheic dermatitis in the diaper area is usually a prescribed steroid cream.
Impetigo: This rash, which can occur anywhere on the body, is caused by bacteria (streptococci or staphylococci). In the diaper area, it shows up in two different forms: Bullous has large, thin-walled blisters that burst, leaving a thin, yellow-brown crust; nonbullous has thick, yellow, crusted scabs and a lot of surrounding redness. The treatment is usually a prescription antibiotic.