How To Treat and Prevent Heat Rash

Treatment for heat rash—sometimes known as miliaria or prickly heat—typically includes cooling down your skin and alleviating itching. Heat rash is skin irritation due to excessive sweating in hot, humid weather. You might develop red pimple-like bumps that itch or become blisters. Those bumps typically appear on the upper trunk, neck, and head but may appear on your bikini line.

People who sweat excessively are more prone to heat rash than others. Heat rash is also common in infants and young children, though it can affect anyone at any age. Read on to learn how to treat a heat rash and other skin problems that closely resemble it.

What Causes Heat Rash?

A heat rash occurs when something, such as bacteria or debris, blocks your sweat glands. As a result, sweat flows backward into your skin layers. That blockage causes inflammation, redness, and swelling.

The rash often appears as red clusters of pimple-like bumps or small blisters on the upper body, neck, and head. Those bumps can be painful and itchy. People with darker skin might develop white spots on their skin, surrounded by a dark halo. Your skin may feel prickly if the bumps rupture and release built-up sweat.

Risk Factors

Anyone can develop a heat rash, but infants and children are likelier than others. That's because their sweat glands are not yet fully developed.

Other factors that increase your heat rash risk:

• Certain medications (e.g., isotretinoin, an oral medication that treats acne)
• High fevers
• Hot and humid weather
• Hyperhidrosis, which causes excessive sweating
• Sweating
• Tight clothing
• Transdermal drug patches (e.g., nicotine patches)
• Vigorous physical activity

How Is Heat Rash Diagnosed?

A healthcare provider can typically diagnose heat rash by examining your skin. The appearance and location of blisters and bumps usually confirm heat rash.

Lab tests usually are not necessary, but a healthcare provider might use other diagnostic tools like:

• Dermoscopy: A healthcare provider will use a dermatoscope, a magnifying glass-like tool, to examine your skin closely. Dermoscopy helps diagnose heat rash in people with darker skin.
• High-resolution optical coherence tomography (HR-OCT): This imaging test helps see what's blocking your sweat glands.
• Skin punch biopsy: A healthcare provider will use a round bland to remove a sample of your skin for testing. A punch biopsy helps confirm heat rash.

Treatment for Heat Rash

Treatment aims to cool down your skin, alleviate heat rash symptoms, and minimize your infection risk. Heat rash typically goes away within 24 hours with at-home care.

Treatments include:

• Cool down: Try cooling down and allowing your skin to breathe if you notice a heat rash. Remove tight clothing and any bandages or patches. Apply a cool compress to the affected area, Alok Vij, MD, a dermatologist at Cleveland Clinic, told Health. You might also take a cold shower and allow your skin to dry out.
• Moisturize: Apply an over-the-counter (OTC) moisturizer once you dry off excess water from cooling down. Make sure that the moisturizer is not oil-based, said Dr. Vij. Oil-based products may clog your pores, which is the opposite of what you want to do if your sweat glands are blocked.
• Apply anti-itch cream: Use calamine lotion for quick relief from itching, Andrew Alexis, MD, MPH, a dermatologist at Weill Cornell Medicine, told Health. Consider using topical hydrocortisone to eliminate redness, itching, and swelling if your rash looks inflamed.

You may need additional treatments if an underlying health condition, such as hyperhidrosis, causes your heat rash. For example, a healthcare provider might prescribe antiperspirants to reduce how much you sweat.

How To Prevent Heat Rash

You can protect your skin against heat rash by keeping you body cool and dry. Ways to prevent heat rash include:

• Do not use creams, ointments, and powders on infants. Those products heat their skin and block their sweat glands. 
• Exercise indoors if it's hot outside.
• Take a cool shower if your skin gets too hot.
• Use air conditioning and fans as much as possible. 
• Wear light-weight clothing made of cotton that fit loosely around your skin.

Other Conditions Easily Mistaken for Heat Rash

Heat rash can mimic bacterial and fungal infections. It's important to see a healthcare provider if you do not know what's irritating your skin.

A healthcare provider might try to rule out other skin conditions that mimic heat rash, such as:

• Drug rash: You might have an allergy to certain medications, which results in a skin rash. Common drug allergies include anti-seizure medications, insulin, and penicillin.
• Folliculitis: This is inflammation of hair follicles through which your hair grows. Shaving and tight clothing commonly damage or block your hair follicles, which causes itchy bumps.
• Fungal skin infection: This may happen if the fungi that usually live on your skin grow out of control (cutaneous candidiasis). People usually develop fungal skin infections in creased areas like the armpits and groin. Fungi also typically cause diaper rash in infants.
• Grover's disease: This rare skin condition causes small, itchy, pink bumps on the trunk.
• Insect bites and stings: You might develop a painful, red, swollen rash that burns or itches if you come into contact with bees, fire ants, mosquitos, or other insects.
• Lymphocytoma cutis: This rare skin condition resembles a type of blood cancer (lymphoma) that causes skin rashes. Lymphocytoma cutis is non-cancerous.
• Viral exanthem rash: Some viral infections, such as chickenpox (varicella) and herpes simplex, cause red bumps and spots that may itch.

When To Contact a Healthcare Provider

See a healthcare provider, such as a dermatologist, if at-home treatments do not work: "If that [rash] doesn't resolve it in a matter of days, and the condition continues to worsen, that would be an absolute indication to see a dermatologist," said Dr. Alexis.

A heat rash can sometimes become infected if blisters develop. A dermatologist may prescribe a topical antibiotic, such as clindamycin, if you have a bacterial infection.

Contact a healthcare provider if you develop symptoms like:

• A fever
• A rash that spreads suddenly and quickly all over your body
• Blisters, especially near your eyes, mouth, and genitals
• Crusting
• Green or yellow fluid draining from the affected area
• Pain near the affected area
• Red streaks near the rash
• Skin that feels warm to the touch

A Quick Review

Heat rash treatment mainly involves cooling down your skin. Applying a cool compress, removing tight clothing, and taking a cool shower can help. You might develop an infection if you develop blisters. Talk to a healthcare provider right away if you notice crusting, fluids draining from the affected area, pain, and red streaks.

You can prevent a heat rash by keeping your skin cool and dry. Wear breathable, loose-fitting clothing, exercise indoors if it's hot outside, and use air conditioning or a fan to cool off.