Pimples on a Baby's Bottom: Causes and Treatment

Pimples on a baby's bottom may be a sign of a local condition or represent the beginning of a generalized infection. Learn more.

Reviewed and approved by the doctor Sandra Golfetto Miskiewicz.

Written by Sandra Golfetto Miskiewicz

Last update: 10 July, 2023

One of the great concerns of mothers has to do with skin rashes on their babies’ skin, especially when they appear in the diaper area. But pimples on a baby’s bottom are one of the most frequent conditions during the first months of life and one of the most common causes of consultation with a pediatrician.

The skin is the largest organ of the human body and acts as a protective barrier against the environment. However, in younger children, it’s a thinner and more fragile tissue, which makes it more vulnerable to external aggressions, such as humidity or the acidity of urine.

Keep reading and learn more about this topic and how to preserve the delicate dermis of your little one.

Why do pimples on a baby’s bottom occur?

As we said, babies’ skin is extremely sensitive to environmental aggressions. For this reason, there are multiple causes for the appearance of those red pimples that appear on the buttocks. In general, these are accompanied by some other signs or symptoms, which help the pediatrician to determine the cause and thus, offer the most appropriate treatment. Do you want to know the most frequent causes? Keep reading.

Insect bites

Insect bites are usually isolated, reddish, and very itchy lesions in the form of bumps. In general, in the case of mosquitoes or bees, they appear on exposed skin areas, but in the case of fleas, they can appear on areas covered by clothing or under the diaper. In the case of the latter, several flea bites may appear together (separated by a few centimeters) and affect several family members at the same time.

Diaper dermatitis

Diaper dermatitis is an inflammatory reaction of the skin to local irritants. For example, heat, moisture, acid from urine, and the rubbing of synthetic diapers. In its initial stage, it usually manifests as small, reddish, non-confluent pimples on reddened or dry, slightly scaly skin. Generally, it doesn’t affect the inguinal folds but appears in areas that come into direct contact with feces, urine, or diaper plastic.

Bacterial infections

One of the most common bacterial infections is folliculitis. This is the inflammation of a hair follicle, which is the sac that envelops the base of the hair within the skin. When a germ enters it, it becomes infected and inflamed. This causes the skin to become raised, red, hot, and painful to the touch, and in some cases, pus will emanate through a hole.

Viral infections

Some viral infections often affect the skin of infants and are very contagious. Some examples are the following:

• Chickenpox is a disease caused by the herpes zoster virus. It usually involves fever, malaise, and mild respiratory symptoms. After 24 to 48 hours, macular-papular skin lesions appear, which progress to vesicles in the following days. They first appear on the face and trunk, then on the baby’s extremities and bottom.
• Genital herpes: This is caused by infection by the herpes simplex virus type 2 and manifests as confluent vesicles that rupture easily when rubbed. This opens the door to superinfection by bacteria of the skin flora and allows pimples to form.
• Monkeypox: This infection is less common in infants and starts as painful pimples or blisters up to 3 weeks after contact with an infected person. The genital area is usually the most common, but they can also appear on the hands, feet, chest, face, or mouth.

Seborrheic dermatitis

Also known as cradle cap, it’s caused by the overgrowth of a fungus that’s part of the skin’s microbiota, called Malassezia furfur . It’s believed that the influence of maternal hormones passed to the baby through the placenta before birth could favor the increased production of sebum in the sebaceous glands and condition the appearance of this condition.

Seborrheic dermatitis usually affects the scalp, but can also spread to other areas of the body, including the diaper area and armpits. They appear between the second and tenth week of life and have been associated with the development of atopic dermatitis later in life.

Warning signs

If your baby has the following signs in the context of a skin rash anywhere on the body, it’s important that you see your pediatrician as soon as possible:

• Poor general condition
• Fever
• Weight loss
• Lack of appetite
• A tendency to sleep or difficulty staying awake
• Widespread outbreak on the skin or lack of spontaneous improvement

How to treat pimples on a baby’s bottom

The treatment of this condition will depend on the cause and the particularities of the case. In general, it’s local irritation, so you’ll need to keep the baby’s skin moisturized and isolated from contact with irritants, such as diaper plastic, urine, and feces.

As a first step, you need to ensure frequent diaper changes, especially during very hot and humid periods. It’s also important to avoid cleaning with harmful agents, such as alcohol wipes or perfumed soaps. Once the dirt has been removed, it’s important to apply an oily solution on the skin of the buttocks (such as oils and pastes) to act as a moisture repellent.

When infected skin wounds are added, such as folliculitis or mycosis, local or oral antibiotics or antifungals can be added, depending on the case. Most viral infections resolve on their own within 7 to 10 days, although in specific cases, such as genital herpes, acyclovir may be used.

Preventing the appearance of pimples on a baby’s bottom is possible!

If you take a few precautions, you can prevent the appearance of pimples on a baby’s bottom. To do this, you should choose highly absorbent diapers and change them frequently. In addition, it’s important to keep the area clean with daily baths and to gently clean the genital area with mild, neutral substances. Also, the use of zinc oxide-based creams is positive to protect the skin of the child and create a barrier against urine and feces. Finally, it’s essential that the person who changes the diaper washes their hands before and after putting it on.

Don’t forget, if you have any doubts about your baby’s care, be sure to consult your family doctor.