Baby Heat Rash: Causes, Types, and Treatments

Your baby’s skin can seem so sensitive and fragile, and many parents feel responsible if anything irritates it. One common skin condition in infants is baby heat rash. While this condition can sometimes cause discomfort for your baby, knowing its causes and treatments can help you avoid, recognize, and manage it effectively. Here, we’ll explore what baby heat rash is, as well as its symptoms, causes, types, duration, treatments, and prevention.

Baby heat rash (also called miliaria, prickly heat, or sweat rash) is a skin condition that occurs when the eccrine glands and ducts in the skin that make and release sweat get blocked.¹ This blockage leads to small, red bumps or blisters or a pink rash on the skin that can be itchy or painful. These symptoms commonly appear in areas where sweat accumulates, such as the groin, neck, arms, chest, and upper back.^1,2 Heat rash rarely affects the baby’s face.¹

When babies’ bodies heat up and sweat, their sweat ducts can get clogged.² Babies have delicate skin and a less efficient sweating system than adults, making them more susceptible to conditions that cause sweating and overheating.³ Some common causes of baby heat rash include:

• Hot and humid conditions: Weather that causes sweating can contribute to baby heat rash.^1,2
• Fever: Just like warm weather can heat up a baby’s body and cause them to sweat, so can a fever.⁹
• Ointment: Babies can also get heat rash in the winter if creams or ointments applied to their skin cause clogged ducts and trap sweat. Lanolin ointment applied to the mother’s nipples for breastfeeding can also cause baby heat rash if it transfers to baby’s skin on their face and blocks their pores.² This could be mistaken for teething rash, a similar condition caused by drool irritation rather than sweat.⁴
• Tight clothing: Clothes that are tight or rub on the skin can cause obstruction of sweat ducts.^1,2
• Exercise: Heat rash can also appear in a toddler and older child due to exercise causing sweating.²

There are three types of heat rash, each varying in severity and appearance. Heat rash is classified by how deep the blockage occurs and how they present differently:¹

Miliaria crystallina is the mildest and most superficial form of heat rash, presenting as tiny, clear, fluid-filled blisters that resemble water droplets and break easily. It generally doesn’t cause discomfort and resolves quickly with cooling measures.¹

This is the most common type of heat rash in babies. Miliaria rubra involves a deeper blockage of the sweat ducts. Sweat gets trapped deeper in the skin, causing an inflammatory response, usually appearing as redness. Inflammation causes the classic heat rash symptoms, including red, itchy bumps and discomfort that may worsen with increased sweating.¹

This is a rarer form of heat rash that occurs deeper in the skin layers. It typically happens after numerous repeated episodes of miliaria rubra and in extremely hot environments, so it’s less common in babies than adults. Miliaria profunda presents as larger, flesh-colored bumps or cysts that can be extremely itchy or have no symptoms.¹

The duration of heat rash varies depending on the type, severity, and steps taken to treat it. In most mild cases, heat rash can resolve on its own within a few hours to a couple of days once the baby is moved to a cooler environment and their sweat glands are no longer blocked.¹ However, if the rash persists or worsens despite treatment, your baby develops a fever without a known cause, or the rash spreads or has pus to indicate infection, you should contact your child’s pediatrician.²

Remember, heat rash typically resolves without treatment.¹ To speed up recovery, effective heat rash treatment focuses on relieving the symptoms and preventing further sweating. Here are some methods to consider:

The simplest home remedies for heat rash involve efforts to lower your baby’s temperature. Move your baby to a cooler, less humid environment. Dress them in lightweight, breathable clothing and keep them in a well-ventilated room. You can try a cool washcloth or a lukewarm bath without soap to cool them down, but don’t let them soak in the cold for more than 10 minutes.² You can also use a fan to cool them down, supervising them to ensure their fingers stay away from the fan blades.

When your baby has a known cause for a fever, such as a cold or other viral illness, treating the fever can help lower their body temperature and thus help treat the heat rash. Tylenol (acetaminophen) and Motrin (ibuprofen) are the most common medications used to treat fever.¹⁰ If you’re unsure which one or how much to use, contact your pediatrician’s office for guidance. Also, reach out if you’re unsure of the cause of the fever and/or rash.

Over-the-counter creams specifically designed for heat rash can help soothe the affected area. However, many of these creams aren’t meant for small infants, so consult your pediatrician before applying them. Here are some ingredients to look for in a heat rash cream for your baby:

• Aloe vera: This can cleanse, cool, moisturize, and disinfect the skin, but be sure not to apply too much and clog the sweat ducts.⁵
• Calamine: Calamine lotion may also be helpful when applied to heat rash, but again, ensure it’s safe for your baby’s age.²
• Hydrocortisone: For more severe cases of baby heat rash, a mild steroid cream like hydrocortisone cream for baby or triamcinolone (prescription) can decrease inflammation and itching. Be sure to use a cream, not an ointment, which could further block the sweat ducts.^1,2

Similar to treatment, preventing heat rash involves keeping your baby cool and comfortable to minimize sweating. Here are some practical tips on how to prevent heat rash:

Choose lightweight, breathable fabrics such as cotton for your baby’s clothing. Cotton and other natural fabrics absorb moisture, keeping the skin cool and dry.⁶ Don’t dress them in anything too tight, and stick to light-colored clothing that won’t trap heat against your baby’s body.⁷

Ensure your baby drinks plenty of fluids to stay hydrated. Proper hydration can help regulate their body temperature and reduce sweating. Babies under 6 months old should only have breastmilk or formula to maintain hydration, but they may need more milk than usual in hot conditions.⁷

Maintain a cool environment wherever possible. If air conditioning isn’t available, use fans and keep the room well-ventilated.⁶ Also, be sure to cool the car — my babies always sweat so much in the car in the summer because the air conditioning doesn’t reach them right away. If possible, start your car and run your air conditioning for a minute or two before strapping them into the hot car seat. Just remember: Never leave a baby alone in a parked car, even if it feels cool outside!⁷

Keep your baby out of direct sunlight (particularly during the hottest parts of the day) to prevent overheating. It’s best to keep them in the shade or use UV-protecting hats and clothes whenever possible.² If they must be in the sun, use a lightweight mineral baby sunscreen that won’t clog their pores.⁸

5. Avoid Ointments and Powders

Ointments and other greasy and thick skin products, such as those used to treat another skin condition called eczema, can clog sweat glands and make heat rash worse.² It was once thought that baby powder would absorb moisture, but it doesn’t prevent heat rash. It can actually clog pores and trap heat, contributing to heat rash in babies.⁶

Give your baby lukewarm baths to help cool their skin and remove sweat when they’re overheated. Avoid using harsh soaps or bubble baths that can irritate the skin further. While exfoliating isn’t recommended for baby skin, gently rinsing and cleansing your baby frequently can help prevent the buildup of sweat and skin residue that clogs sweat ducts and causes heat rash.²

Baby heat rash can happen regardless of your efforts to prevent it. Fortunately, it’s typically mild and resolves on its own in hours to days. While it can cause temporary discomfort for your baby and distress for you, it’s usually not a serious health concern. By understanding the signs, symptoms, prevention, and treatment, you can effectively manage and treat heat rash in your baby. Regular cooling, proper clothing, and awareness of environmental factors are key to preventing and alleviating this condition. If you have concerns or your baby’s heat rash persists despite home remedies, consult your pediatrician. Keeping your baby comfortable and cool is the best way to ensure their well-being during those hot and humid days.