As it turns out, Stephanie B.’s daughter Sophia has a sensitive tushie. “She’s had a variety of problems in the diaper area — she has sensitive skin and is prone to rashes ranging from spots to bumps to violent blisters that made her scream if we went near the change table,” says the Hamilton, Ont. mom. Sophia’s parents tried remedy after remedy to soothe her bottom: they’d dry it with a cool hairdryer after a change; apply multiple creams and lotions; bathe her in baking soda; use wet washcloths instead of wipes. What was the miracle cure? A steroid cream from Sophia’s doctor, a barrier cream and giving Sophia’s bottom “air-time.”

As you’re likely discovering, baby’s first year might require an MD’s license when it comes to diagnosing the mystery spots and dots that arise on your baby’s bottom. “Newborn skin, compared to adults, is so thin and transparent that it reacts to things very quickly, and how it reacts becomes very visible,” says Dr. Henry Ukpeh, a pediatrician in Trail, B.C.

Here’s how to decode what’s going on with your baby’s bum.

Diaper rash (a.k.a. diaper dermatitis)
“Babies get this often just from the contact of their sensitive skin and the stuff in the diaper,” says Dr. Jeremy Friedman, chief of pediatric medicine at Toronto’s Hospital for Sick Children and co-author of Canada’s Baby Care Book (Robert Rose).

Symptoms: The diaper area is likely to be red (from mild to bright), puffy and in severe cases, can become quite raw.

What to do? Gently clean the area with a cloth soaked in warm water. Apply a diaper cream, preferably a thick one, to act as a barrier between your baby’s bottom and urine and feces. Changing your baby’s wet or dirty diapers as soon as possible (with some time open to the fresh air to let her bottom dry) can also help.

Fungal Infection

Also known as a yeast (candida) infection, which in babies can also occur outside of the genital area. “Fungi or yeasts like to grow in warm, moist, dark places like diapers, and it’ll look like bad diaper dermatitis,” says Dr. Friedman. “To tell the difference, check in the thigh skin folds. If it’s red inside the fold, it’s likely a fungal infection, because this area isn’t exposed to the irritants in the
diaper. But it is possible to have both at the same time.”

Symptoms: Red patches with blotchy red spots extending beyond the main rash.
What to do? If it’s fungal only, apply an antifungal cream such as Canesten to clear it up, but if it’s a dual rash, you’ll also need to smear on a barrier paste such as petroleum jelly or a zinc oxide ointment to soothe baby’s bottom and protect it from the irritants in the diaper. “Or if it’s really bad, doctors will often provide a very mild steroid cream to treat it, which can be combined with an antifungal cream,” adds Dr. Friedman.

Heat rash/prickly heat

These usually rise up on the parts of the body that get sweaty, especially baby’s chubby folds of skin in the neck. While most common in the summer, a baby layered in clothes for cooler temperatures is also susceptible. “It’s made worse by over-bundling the baby,” says Dr. Friedman.

Symptoms: Reddish blotches and small red/pink bumps.

What to do? Change the baby into cotton clothing and reduce exposure to excessive heat and humidity.

Food-related sensitivity
A variety of foods, especially acidic ones such as tomatoes, can change the consistency of bowel movements, which then irritate baby’s bottom.

Symptoms: A red rash around baby’s anus. True allergic reactions are more likely to be a hives-type of raised wheal that gets itchy and spreads quickly around the body.

What to do? To make detection of food-related sensitivity easier, introduce only one new food at a time every three to five days and watch for any reaction.

When to call the doctor
Most diaper rashes clear up within a week or two of treatment. However, if the rash lingers or looks infected (blisters, open sores), or your child develops a fever, contact your doctor.

With a two-year-old daughter, writer Astrid Van Den Broek has seen—and continues to see—her fair share of red spots, dots and blotches.