Can Diarrhea Cause a Rash in a Toddler?

Parents do everything to keep their kids healthy, but kids still get sick.

If your toddler experiences a rash and diarrhea, he may have a medical condition, such as fifth disease or a milk allergy.

Diarrhea can also be the cause of a toddler’s diaper rash. Always consult with your doctor for proper diagnosis and treatment.


Fifth disease starts with mild, cold-like symptoms. Once the illness seems to disappear, a rash appears on the face that resembles a slapped cheek and then extends to other areas of the body. Diarrhea is sometimes present with fifth disease as well as a sore throat, swollen glands and red eyes. If your toddler has a milk protein allergy, immediate symptoms are a rash, wheezing and possible vomiting. As the allergy progresses, diarrhea, abdominal cramps and itchy skin around the mouth may be present. The severity of the reaction varies from person to person. A diaper rash in the anal region that’s caused by diarrhea will be red, swollen and may have patches of red skin.

The Underlying Culprit

Newborn baby in diaper lying on plush blanket

What Are the Symptoms of a Milk Allergy in a Toddler?

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Fifth disease is caused by parvovirus B19 and can easily be spread by the fluids from an infected person’s nose, mouth or throat. If these droplets land on an object, your toddler can become infected from touching the object and then putting his fingers in his mouth.

A milk protein allergy develops when the immune system recognizes milk proteins as being harmful and releases histamines and other chemicals. The two types of milk proteins that cause an allergic reaction are casein and whey. Diarrhea can also expose your child to stools for a prolonged period of time resulting in a diaper rash caused by the skin irritation.

Making it Better

Any time your toddler has diarrhea, make sure he gets plenty of fluids and drinks an oral hydration solution to prevent dehydration. Antibiotics will be ineffective for fifth disease and can actually cause a diaper rash. Acetaminophen can ease a sore throat and fever, but the virus will need to run its course. A milk allergy can be treated with antihistamines. If the allergic reaction is severe, your toddler must go to the emergency room for an injection of epinephrine. Diaper rashes from diarrhea can be treated with zinc oxide ointments or petroleum.


Newborn baby in diaper lying on plush blanket

A Toddler With Redness on the Face

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No vaccination exists for fifth disease, but encouraging your toddler and other family members to wash their hands frequently can reduce the spread of viruses.

In the case of a milk allergy, your toddler must avoid milk and other dairy products. Even if a product says milk-free or dairy free, it can still contain casein or whey. Always ask how food is prepared before having it served to your toddler. Change diapers frequently and use warm water to clean the diaper region for diaper rash. Ointments can reduce your child’s risk of a diaper rash from diarrhea because the ointment provides a protective layer for your toddler’s skin.