Table of ContentsView AllTable of ContentsSymptomsFinding ReliefManaging Heat RashWhen to Call a ProviderPrevention
Table of ContentsView All
View All
Table of Contents
Symptoms
Finding Relief
Managing Heat Rash
When to Call a Provider
Prevention
Heat rash, also known aseccrine miliaria, sweat rash, and prickly heat, is askin rashthat causes the skin to turn red and feel warm or prickly (stinging). It also causes small red dots in the affected skin area in people with lighter skin tones and darker spots in people with darker skin tones.
Heat rash occurs in adults and children when the body sweats more than usual. It is more common during the summer months or in hot, dry climates.
Heat rash can also affect newborns because their eccrine sweat glands are not yet fully developed.Eccrine sweat glands open directly onto the surface of the skin and are found in most areas of the body. In newborns, the rash may appear as thin blisters or tiny water blisters on the face, trunk, and arms.
This article will cover what heat rash looks like, finding immediate relief, prevention, and more.
COROIMAGE / Getty Images
How Does Heat Rash Look?
The most common symptoms are itching and small bumps in the affected skin area. In people with lighter skin tones, these bumps may appear red. In people with darker skin tones, they may appear darker than the surrounding skin.
Symptoms in infantsoften appear on the neck, chest, and upper back.Older children may experience a prickly pins-and-needles feeling, and babies may have tiny water blisters in the affected skin area.
This photo contains content that some people may find graphic or disturbing.See PhotoReproduced with permission from ©DermNetdermnetnz.org2023.
This photo contains content that some people may find graphic or disturbing.See Photo
This photo contains content that some people may find graphic or disturbing.
Reproduced with permission from ©DermNetdermnetnz.org2023.
Location
Heat rash is sometimes divided into three categories based on the level of blockage of the sweat ducts. Categories are:
How to Treat a Heat Rash on the Face in Babies and Adults
Onset of Symptoms
Symptoms of heat rash typically come quickly. The rash will appear within minutes to hours of excessive sweating.
Sweating is the body’s response to heat and is intended to cool. When sweat leaves the pores of the skin, it evaporates and takes body heat with it.
If the skin’s ducts become clogged, sweat cannot reach the surface and evaporate. It will become trapped and can cause heat rash.
Why Do I Sweat So Much? How Much Is Too Much and Potential Causes
Appearance and Texture
Depending on the type of heat rash you are experiencing, the appearance and texture of the rash will differ.
Miliaria crystallina presents as a clear or skin-colored heat rash.The rash will present with fluid-filled bumps on the skin. It can affect up to 9% of newborns.
Miliaria rubra is the type of miliaria often called prickly heat because it causes a burning itch and presents as red-colored in lighter skin tones and gray, purple, or dark brown in darker skin tones. This type of heat rash is more common in adults than children.If this type of heat rash causes pustules, the affected skin area may appear white or yellow. Pustules can be painful or become infected.
Miliaria profunda causes a heat rash that occurs deep into the skin layers and occurs frequently (chronic).It can cause skininflammation(swelling and discoloration), irritation, and infection. Miliaria profunda sometimes presents with large, firm skin bumps when exposed to heat. It can also cause systemic symptoms like nausea and dizziness.
Skin Tone Presentation
Heat rash can present differently on different skin tones. For example, heat rash on lighter skin tones often is red, and on darker skin tones, it can be a gray, purplish, or dark brown.
The difference is due to the amount of melanin in the skin. Melanin is the substance that gives hair, skin, and eyes their color (pigment).
What a Heat Rash Looks Like on Darker Skin (and What to Do Next)
Sensations
Heat rash can be uncomfortable, and some types are more painful than others. For example, the small, inflamed blisters of miliaria rubra can be extremely itchy.On the other hand, milaria crystallina’s clear, fluid-filled bumps tend to not be painful or itchy.
Extreme itch is a symptom of the most painful type of heat rash, miliaria profunda. If it causes pustules, the pus-filled bumps may become inflamed and swollen.
Heat Exhaustion
Heat rash can sometimes be present along withheat exhaustion. With heat exhaustion, the body overheats and cannot cool down.
Symptoms of heat rash include:
Is It a Heat Rash or a Skin Allergy?
The main difference between a heat rash and a skin allergy is that heat rashes occur in warm weather, especially when you’re outdoors and sweating and your sweat ducts become obstructed.
An allergy is an immune response to an allergen, such as plant, cosmetic, metal, food, or insect bites.A skin allergy may present with hives—red, raised, itchy bumps that may burn and sting. Hives typically present in more than one body area, whereas a heat rash appears in one affected area.
Additional skin conditions that may look like heat rash are:
Immediate Relief to Soothe Heat Rash
Some home remedies can provide quick relief for heat rash.Home remedies for heat rashinclude:
For an infant with heat rash:
Managing Heat Rash Over Several Days
Heat rash typically resolves in a few hours, but if it is severe, it may take days or weeks to go away. A severe rash may require over-the-counter (OTC) treatments.
It is always a good idea to check with your healthcare provider before using OTC medicines to manage heat rash.
OTC options for managing heat rash include:
What Does a Heat Rash Look Like and How Is It Treated?
When to Consult a Healthcare Provider
If you experience severe symptoms of heat rash, contact a healthcare provider. Severe symptoms include:
For an infant or younger child, contact your child’s healthcare provider if:
Staying Ahead of Heat Rash on Hot Days
While heat rash typically isn’t dangerous, it can be uncomfortable. Fortunately, it is preventable.
Summary
Heat rash is a common but uncomfortable skin irritation that occurs during hot and humid weather. Different categories of heat rash cause varying symptoms, including clear, fluid-filled blisters and red or dark itchy bumps. Heat rash can affect anyone, including infants and children.
Cooling down and wearing loose, lightweight clothing can help manage heat rash. If symptoms of heat rash last longer than a few days, if the rash is severe or painful, or if you or a child shows signs of infection, including fever, contact a healthcare provider.
15 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Harvard Health Publishing.Heat rash: how to spot it and what to do.Seattle Children’s HospitalHeat rash.UpToDate.Miliaria.DermNet.Heat rash (miliaria): images, causes, and treatment.Chadha A, Jahnke M.Common neonatal rashes.Pediatr Ann. 2019;48(1):e16-e22. doi:10.3928/19382359-20181206-01Sanadi RM, Deshmukh RS.The effect of vitamin C on melanin pigmentation - a systematic review.J Oral Maxillofac Pathol. 2020;24(2):374-382. doi:10.4103/jomfp.JOMFP_207_20Centers for Disease Control and Prevention.Warning signs and symptoms of heat exhaustion.Harvard Health.Rash.DermNet.Acute generalised exanthematous pustulosis (AGEP): treatment, images, and causes.DermNet.Bacterial folliculitis.Yale Medicine.Grover’s disease.World Health Organization.Herpes simplex virus.Mount Sinai.Erythema toxicum Information.Reynertson KA, Garay M, Nebus J, et al.Anti-inflammatory activities of colloidal oatmeal (Avena sativa) contribute to the effectiveness of oats in treatment of itch associated with dry, irritated skin.J Drugs Dermatol. 2015;14(1):43-48.DermNet.Aloe vera and the skin.
15 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Harvard Health Publishing.Heat rash: how to spot it and what to do.Seattle Children’s HospitalHeat rash.UpToDate.Miliaria.DermNet.Heat rash (miliaria): images, causes, and treatment.Chadha A, Jahnke M.Common neonatal rashes.Pediatr Ann. 2019;48(1):e16-e22. doi:10.3928/19382359-20181206-01Sanadi RM, Deshmukh RS.The effect of vitamin C on melanin pigmentation - a systematic review.J Oral Maxillofac Pathol. 2020;24(2):374-382. doi:10.4103/jomfp.JOMFP_207_20Centers for Disease Control and Prevention.Warning signs and symptoms of heat exhaustion.Harvard Health.Rash.DermNet.Acute generalised exanthematous pustulosis (AGEP): treatment, images, and causes.DermNet.Bacterial folliculitis.Yale Medicine.Grover’s disease.World Health Organization.Herpes simplex virus.Mount Sinai.Erythema toxicum Information.Reynertson KA, Garay M, Nebus J, et al.Anti-inflammatory activities of colloidal oatmeal (Avena sativa) contribute to the effectiveness of oats in treatment of itch associated with dry, irritated skin.J Drugs Dermatol. 2015;14(1):43-48.DermNet.Aloe vera and the skin.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Harvard Health Publishing.Heat rash: how to spot it and what to do.Seattle Children’s HospitalHeat rash.UpToDate.Miliaria.DermNet.Heat rash (miliaria): images, causes, and treatment.Chadha A, Jahnke M.Common neonatal rashes.Pediatr Ann. 2019;48(1):e16-e22. doi:10.3928/19382359-20181206-01Sanadi RM, Deshmukh RS.The effect of vitamin C on melanin pigmentation - a systematic review.J Oral Maxillofac Pathol. 2020;24(2):374-382. doi:10.4103/jomfp.JOMFP_207_20Centers for Disease Control and Prevention.Warning signs and symptoms of heat exhaustion.Harvard Health.Rash.DermNet.Acute generalised exanthematous pustulosis (AGEP): treatment, images, and causes.DermNet.Bacterial folliculitis.Yale Medicine.Grover’s disease.World Health Organization.Herpes simplex virus.Mount Sinai.Erythema toxicum Information.Reynertson KA, Garay M, Nebus J, et al.Anti-inflammatory activities of colloidal oatmeal (Avena sativa) contribute to the effectiveness of oats in treatment of itch associated with dry, irritated skin.J Drugs Dermatol. 2015;14(1):43-48.DermNet.Aloe vera and the skin.
Harvard Health Publishing.Heat rash: how to spot it and what to do.
Seattle Children’s HospitalHeat rash.
UpToDate.Miliaria.
DermNet.Heat rash (miliaria): images, causes, and treatment.
Chadha A, Jahnke M.Common neonatal rashes.Pediatr Ann. 2019;48(1):e16-e22. doi:10.3928/19382359-20181206-01
Sanadi RM, Deshmukh RS.The effect of vitamin C on melanin pigmentation - a systematic review.J Oral Maxillofac Pathol. 2020;24(2):374-382. doi:10.4103/jomfp.JOMFP_207_20
Centers for Disease Control and Prevention.Warning signs and symptoms of heat exhaustion.
Harvard Health.Rash.
DermNet.Acute generalised exanthematous pustulosis (AGEP): treatment, images, and causes.
DermNet.Bacterial folliculitis.
Yale Medicine.Grover’s disease.
World Health Organization.Herpes simplex virus.
Mount Sinai.Erythema toxicum Information.
Reynertson KA, Garay M, Nebus J, et al.Anti-inflammatory activities of colloidal oatmeal (Avena sativa) contribute to the effectiveness of oats in treatment of itch associated with dry, irritated skin.J Drugs Dermatol. 2015;14(1):43-48.
DermNet.Aloe vera and the skin.
Meet Our Medical Expert Board
Share Feedback
Was this page helpful?Thanks for your feedback!What is your feedback?OtherHelpfulReport an ErrorSubmit
Was this page helpful?
Thanks for your feedback!
What is your feedback?OtherHelpfulReport an ErrorSubmit
What is your feedback?
