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Heat Rash - Causes, Symptoms, Risk Factors, Diagnosis and Treatment

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Heat rash is a common condition for children and adults, especially during hot, humid weather. Read this article to know more about this condition.

Medically reviewed by

Dr. Syed Raza

Published At May 3, 2022
Reviewed AtNovember 24, 2022

What Is Heat Rash?

Heat rash, also called prickly heat and miliaria, is a common skin condition mainly affecting children and adults in hot, humid weather conditions. Heat rash develops when the blocked pores trap sweat under the skin. Heat rash often affects the areas where sweating is more likely to happen, including the face, neck, under the breasts, under the scrotum, in folds of the skin, and areas where skin rubs together or against clothes, including the back, chest, and stomach. Heat rash can be concerning, uncomfortable, or itchy; it is not dangerous. It usually clears on its own once the skin cools off.

What Are the Symptoms of Heat Rash?

Symptoms of heat rash

The symptoms of heat rash are similar in both children and adults, and they last about two to three days. The common symptoms of heat rash include:

  • Tiny red bumps or spots on the skin (papules).

  • An itching or prickling sensation due to inflammation of the outermost layers of the skin (the epidermis).

  • Mild swelling of the affected area.

  • If bacteria enter the clogged sweat glands, it can lead to inflammation and infection.

What Are the Main Causes of Heat Rash?

Causes of heat rash

Heat rash typically develops due to a blockage and inflammation of sweat ducts in hot, humid conditions. It is not clear why the sweat ducts become blocked, but certain factors contribute to it, including:

  • Immature Sweat Ducts: Heat rash is common in newborn babies that happen in the first week of life. The sweat ducts are not fully developed in newborns. They tend to rupture more easily, trapping perspiration beneath the skin.

  • Tropical Climates: Hot, humid tropical climates can cause heat rash.

  • Physical Activity: Vigorous exercise, hard work, or any other activity that causes heavy sweating leading to heat rash.

  • Overheating: Overheating by dressing too warmly or sleeping under an electric blanket can also lead to heat rash.

  • Prolonged Bed Rest: Heat rash can also develop in individuals who are bed-ridden or immobile for extended periods, especially if they have a fever.

What Are the Risk Factors of Heat Rash?

The factors that make a person more prone to heat rash include:

  • Newborns are more likely to develop heat rash.

  • People living in the tropics are more susceptible to heat rash than people living in temperate climates.

  • Any physical activity that causes heavy sweating, especially if not wearing clothing that allows the sweat to evaporate, can trigger heat rash.

  • Newborns, infants, older adults, and obese individuals with large areas with skin-on-skin contact areas are at greater risk of developing heat rash as they are immobile for long periods and parts of the skin are not exposed to air, resulting in the inability of the sweat ducts to breathe.

  • Vigorous exercise, hard work, or any physical activity that causes a person to sweat heavily may cause a heat rash, especially if the worn clothes do not allow adequate air circulation.

How Is Heat Rash Diagnosed?

No tests are required to diagnose heat rash. The diagnosis of heat rash is based on a physical examination. The doctor examines the rash, possibly using a dermoscopy for a closer inspection. If needed, the doctor may also recommend a skin punch biopsy to detect the cause of the rash.

When to See a Doctor?

Heat rashes are often harmless. They usually heal without problems. But if the symptoms do not resolve in a few days, the heat rashes can become worse and can also lead to bacterial infection, causing inflamed and itchy pustules. See a healthcare provider if a person with heat rash notices the following signs of infection, such as:

  • Severe pain.

  • Increased swelling and redness.

  • The rash area feels warm.

  • Pus coming out from the lesions.

  • Swollen lymph nodes in the areas such as the armpit, neck, or groin.

  • Fever or other signs of illness.

  • Heat exhaustion and an inability to sweat.

How Is Heat Rash Treated?

Avoiding overheating is the best way to treat mild heat rash. Once the skin is cool, the heat rash clears up quickly. However, the doctor may recommend over-the-counter or prescription medications to treat moderate to severe forms of heat rash, including:

Pharmacological Treatments:

1. Ointments

Ointments may help relieve discomfort and prevent complications. Various ointments are available to manage the symptoms of heat rash, such as:

  • Calamine lotion to soothe itching.

  • Anhydrous lanolin to prevent sweat duct blockage.

  • Topical steroids in the most severe cases.

2. Over-the-Counter Antihistamines

Topical or oral antihistamines can relieve the itching associated with heat rash. Consult a pediatrician about which type of antihistamine is better for a child.

3. Lifestyle and Home Remedies

A few tips that can help heal heat rash and soothe the skin include the following:

  • In hot weather, try wearing loose, cotton clothing that helps prevent overheating. Avoid wearing synthetic fabrics and wool, if possible, as they tend to produce itching and irritate the skin.

  • Cool down to avoid sweating. Spend as much as possible in air conditioning or near a fan to make sure there is good ventilation.

  • Bathe or shower in cool water with mild soap helps provide short-term relief from itching. However, excessive showering or bathing should be avoided as it can reduce the natural oils from the skin and may make the condition worse.

  • Use calamine lotion or cool compresses on the affected area to soothe itchy, irritated skin.

How to Prevent Heat Rash?

The most effective way to avoid heat rash is to stay away from situations that cause excessive sweating. Try the following tips to protect the skin from heat rash:

  • Avoid overdressing in the summers. Wear soft, lightweight clothing made from natural fibers such as cotton.

  • Avoid tightfitting clothes that can irritate the skin.

  • If it is a hot, humid climate, spend a few hours daily in a cool space with fans or air conditioning.

  • Keep the sleeping area cool and well-ventilated.

  • Avoid scratching the skin to prevent infection.

  • Keep the affected area dry.

  • Avoid using ointments or creams that contain petroleum or mineral oil to keep the skin moist.

  • Avoid doing activities that cause excessive sweating.

  • Exfoliating the skin two to three times a week removes the dead skin cells that may block the sweat glands.

  • Choose lightweight bedding made of cotton or linen.

  • Change the baby’s diaper immediately after they become wet.

  • Stay hydrated by drinking plenty of fluids.


Heat rash is a common skin problem, especially in a hot, humid climate. The condition usually goes away without treatment, although home remedies can help soothe the rash and relieve the discomfort. If heat rash persists for more than a few days, seek medical attention. Since heat rash occurs when the body overheats and sweats, it can be prevented by keeping the skin cool.

Frequently Asked Questions


How to Get Rid of Heat Rashes?

Avoiding heat exposure is the best way to treat mild heat rash. Once the skin is cool, the heat rash clears up quickly. Over-the-counter or prescription medications, including calamine lotion, topical steroids, and antihistamines are used to treat moderate to severe forms of heat rash.


What Does a Heat Rash Look Like?

The symptoms of heat rash are similar in both children and adults. A heat rash looks like tiny red bumps or spots on the skin (papules). There may be itching or prickling sensation due to inflammation of the outermost layers of the skin (epidermis) and mild swelling of the affected area. Inflammation and infection can occur if bacteria enter the clogged sweat glands.


How Long Does a Heat Rash Last?

On average, heat rashes last for two to three days. Heat rashes usually disappear on their own within two to three days as long as the affected area is not irritated further. Mild heat rashes can resolve within a few hours or days. Severe forms of heat rashes may persist for weeks.


Is It Possible to Get Rid of a Heat Rash Overnight?

Yes, mild heat rashes can resolve within a few hours or days with simple home remedies such as taking cool showers, using a gentle soap, letting the skin air-dry instead of toweling off, and using calamine lotion and cool compresses.


What Is the Best Cream to Put on a Heat Rash?

Hydrocortisone cream (1 %), a type of corticosteroid, available without a prescription is the best cream to help relieve symptoms of heat rash. It should be applied once or twice a day to soothe itching from a heat rash.


Who Can Get a Heat Rash Easily?

Heat rashes are more common in newborns, obese people, and the elderly. People living in hot, humid climates, with limited mobility, and those who do vigorous exercise, hard work, or any physical activity that causes profuse sweating are at a greater risk of developing heat rashes frequently.


How Are Heat Rashes Prevented?

To prevent heat rashes, stay away from situations that cause excessive sweating. On hotter days, wear lightweight clothes made of natural fibers, stay in cool and well-ventilated areas, use air conditioners and fans, take cool showers or baths, use ointment or cream to keep the skin moist, and avoid scratching the skin.


What Are the Clinical Features of a COVID Rash?

COVID rashes are typically discolored as compared to the neighboring skin. On light-skinned people, rashes may appear red, pink, or purple, while on dark skin, these look purple, ashy gray, or dark brown. The affected site may appear swollen or puffy in comparison to the surrounding skin. Some COVID-19 rashes may be itchy.


How Long Do Heat Rashes Last on Babies?

Heat rash is a common problem in babies. They usually go away on their own within three to four days as long as the affected site is not irritated further.
Dr. Syed Raza
Dr. Syed Raza

Family Physician


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