Prickly Heat: Everything You Need to Know

Prickly heat is a skin rash that occurs when sweat is trapped in the skin. Normally, sweat travels to the skin’s surface through a series of small ducts. But these ducts can become clogged and trap sweat inside the skin. This process leads to redness, itching, stinging, or prickling sensations in the affected skin area, and small blisters.

Prickly heat is also called heat rash and miliaria. Hot weather and high humidity are common triggers of prickly heat rash.

This article will cover the symptoms of prickly heat, treatments, complications, and more.  

Causes of Prickly Heat

When you sweat more than usual, your sweat ducts can become blocked, which leaves the sweat trapped deep underneath the skin’s surface. Sweat can also leak out to the top layer of skin, called the epidermis, and become trapped there too.

You can experience prickly heat anytime of the year, but it occurs more frequently during the warm-weather months. People who are used to cooler temperatures might experience prickly heat when they travel to places with significantly higher temperatures than what they are used to.

Prickly heat is also linked to some types of bacteria, including Staphylococcus. These bacteria are normally on the skin without causing a problem, but they can form a film that blocks sweat ducts and contributes to skin conditions.

Additional causes of prickly heat include:

• Fevers
• Tight or warm clothing
  
• Tight bandages
• Medicine patches that stick to skin
• Oral medicines, including beta-blockers
• Health conditions like hyperhidrosis that cause you to sweat excessively
• Exercising or working in hot climates
  

Symptoms

Prickly heat is easily identifiable by its symptoms. The most common symptoms are red bumps and itching on an area of skin that has been exposed to heat and sweat for a long period.

Sometimes, the red bumps form into tiny blisters. The blisters can swell and become itchy, irritated, red, and inflamed as the rash gets worse. Blisters and skin symptoms can spread to other body areas, but the condition is not contagious.

Symptoms in Children and Infants

Prickly heat is more common in children and infants than adults. This is because the sweat glands in children are less strong and healthy, which makes them more likely to get clogged. Also, children’s bodies are not used to rapidly changing temperatures.  

Symptoms of prickly heat in children are similar to those experienced by adults. However, the rash often appears on the face, neck, and groin and can be irritating and uncomfortable.

In addition to general causes of prickly heat, additional causes of the condition in children are:

• Clothing fabrics that do not allow sweat to evaporate from the skin
• Overdressing or wearing heavy fabrics
• Sleeping under too many blankets
• Being in a wet or soiled diaper for too long, especially in humid conditions
  

The symptoms of prickly heat may resemble those of other skin conditions, such as eczema. Talk with your healthcare professional for a diagnosis if your symptoms or your child’s do not improve with home care.

Treatment  

Prickly heat usually does not need any treatment. It often goes away on its own within two to three days. But there are some steps you can take at home to ease symptoms and stay comfortable.  

At-Home Remedies

The first thing you will want to do to manage and reduce symptoms of prickly heat is to find a cooler environment. Other remedies to manage symptoms include:

• Wearing lighter, loose-fitting clothes
• Avoiding skin-care products that irritate your skin
• Using a cold compress on the affected area
• Taking a cool bath or shower
• Keeping the skin cool and dry
• Not scratching affected skin areas 

A variety of over-the-counter (OTC) products can also help you manage and treat symptoms of prickly heat. OTC treatments that can manage prickly heat symptoms include:  

• Calamine lotion to cool skin
• Hydrocortisone cream to help manage symptoms of redness, irritation, and swelling (use 1% hydrocortisone cream and avoid hydrocortisone ointment)
• Topical or oral antihistamines to reduce itching (antihistamine ointments should not be used on a child's skin)
• Camphor or menthol to cool skin and reduce itchiness.
• Anhydrous lanolin (lanolin not containing water) to prevent blockage of the sweat ducts

If you experience a fever with prickly heat, you might consider a fever reducer, such as Advil (ibuprofen) or Tylenol (acetaminophen). If a child gets a fever with prickly heat, contact their doctor right away.

When to Contact a Healthcare Provider 

Prickly heat usually doesn’t require medical care. It will resolve on its own once the skin has cooled. However, there are instances in which you or a child will need medical attention for prickly heat.  

You should visit a healthcare professional if symptoms last longer than a few days or if you think the skin might be infected.

Common signs of skin infections include:

• Increased pain, swelling, redness, or warmth in the affected skin area
• Blisters that crust or have pus draining from blisters
• Fever and/or chills
• Swollen lymph nodes in the armpit, neck, or groin

If your prickly heat rash feels severe or you have other concerns, you should contact your healthcare provider for diagnosis and treatment before symptoms worsen.   

Complications  

The most common complication of prickly heat is infection. Being in a hot environment that triggers prickly heat may also lead to heat exhaustion.  

The most common cause of secondary infection from prickly heat is scratching. This is because scratching causes skin breaks. You will need antibiotic treatment if you develop an infection. Seek medical attention if you experience signs of a skin infection.  

If a person experiences heat exhaustion, they sweat heavily and have cold and clammy skin. They may also experience dizziness, weakness, headache, blurred vision, nausea, confusion and/or difficulty breathing.

Untreated heat exhaustion can quickly become heat stroke, which is a medical emergency. Signs of heat stroke include:

• Fever of 103 degrees or more
• Flushing, hot skin
• Sweating often ceases
• Rapid breathing and heartbeat
• Confusion
• Loss of consciousness
• Seizures (rare)

If you experience or witness signs of heat exhaustion or heat stroke, you need to get emergency help quickly. You should also go indoors or find a shaded area or a fan to help cool down. Try to cool the body with an ice pack or drink cold water.

Prevention  

Prickly heat is a preventable condition. The most effective way to prevent it is to avoid its causes.  

Try the following:  

• Wear light, loose-fitting clothing when out in hot and humid climates.
• Take cool baths and showers when the weather is hot and humid.
• On hot, humid days, spend a few hours in air-conditioned areas or use fans.
• Use lightweight bedding, such as cotton or linen materials.
• Change out of wet or sweaty clothes as soon as possible.
• Change a baby’s diaper immediately after the diaper becomes wet or soiled.
• Drink plenty of fluids to stay hydrated.

If you have a condition like hyperhidrosis that causes you to sweat more, talk to your healthcare professional or a dermatologist about treatment to reduce sweating, especially during the warm weather months.  

Summary  

Prickly heat is a rash that appears as small bumps. It is caused by blockage of the sweat glands, which is often due to being in hot, humid areas. It can cause the skin to be itchy, inflamed, and painful. Most of the time, prickly heat can be treated at home and with OTC medicines.

You should reach out to your doctor if the prickly heat rash seems to be getting worse, you suspect an infection, or you experience signs of heat exhaustion. It is possible to prevent prickly heat by managing its sources and staying cool and hydrated in hot, humid climates. 

 A Word From Verywell

Prickly heat is rarely a concerning condition and it often resolves on its own. However, it is still important to be mindful of its symptoms and complications. Make sure you stay hydrated and keep cool during the warm-weather months and while exercising or working outdoors.  

If you experience a rash that seems to be getting worse or appears infected, you should see your healthcare provider right away. You should also be aware that scratching can cause the skin to break and become infected. Lastly, watch out for signs of heat exhaustion and move to a cooler area as soon as you start to experience signs of this condition.