Heat Rash (Miliaria) - Symptoms, Causes & Treatment
By ScanSkinAI Editorial Team✓ Reviewed for medical safetyLast updated June 2026
A skin condition caused by blocked sweat glands, resulting in small, itchy bumps. Common in hot, humid weather or when overdressed.
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Quick Answer
Heat rash, also known as prickly heat or miliaria, is a common skin condition caused when your sweat glands become blocked. The trapped sweat creates small, itchy red bumps or tiny blisters that often feel like they are prickling or stinging. This usually happens in hot, humid weather, during intense exercise, or when wearing non-breathable clothing. Fortunately, it generally goes away on its own once you cool down. Mild cooling measures and wearing loose clothing are usually all that is needed to clear it up quickly.
Symptoms
- Small red bumps
- Prickling or stinging sensation
- Mild swelling
- Usually in areas where sweat collects
- May have tiny blisters
Causes & Risk Factors
- Blocked sweat glands
- Hot, humid weather
- Heavy clothing
- Immature sweat glands (in babies)
- Excessive sweating
Treatment & Management
- Cool the skin
- Loose clothing
- Stay in air conditioning
- Calamine lotion
- Avoid heavy creams
- Usually resolves once cooled
When to See a Doctor
If rash doesn't improve in a few days, develops pus, or you have fever
Frequently Asked Questions
Why do I get heat rash in the summer?
Heat rash happens when your sweat ducts become blocked and trap perspiration beneath your skin. In the summer or intense humidity, your body sweats more to cool down. If you wear tight clothing or heavy fabrics, the sweat cannot easily evaporate. The trapped sweat irritates your skin, leading to the itchy, prickly bumps characteristic of this rash.
What does prickly heat look and feel like?
Prickly heat typically appears as clusters of small red bumps or tiny, clear blisters. It most often develops in areas where sweat naturally collects, such as your neck, chest, groin, or within the creases of your elbows and knees. As the name suggests, the rash often causes a distinct prickling, stinging, or intense itching sensation as the trapped sweat irritates the surrounding tissue.
How can I treat a sweat rash at home?
The most effective way to treat a sweat rash is to cool your skin and prevent further sweating. Move to an air-conditioned or well-ventilated space and wear loose, breathable clothing. You can apply a cool compress to soothe the itching. Calamine lotion can also help reduce the prickling feeling. Avoid thick lotions and heavy creams, as these can block your sweat glands even further.
How long does it usually take for heat rash to go away?
In most cases, heat rash is temporary and clears up on its own within two to three days. As soon as you remove the source of the heat and allow your skin to cool and breathe, the blocked sweat glands will open, and the bumps will fade. If you continue to sweat heavily or wear restrictive clothing, the rash may persist longer.
When should I see a doctor about these itchy bumps?
You should consult a healthcare professional if your rash does not improve after a few days of cooling measures, or if it seems to be getting worse. Seek medical advice quickly if you notice signs of an infection, such as increased warmth and swelling, bumps filling with pus, or if you develop a fever and chills alongside the skin breakout.
Why do babies get heat rash so easily, and how can I prevent it?
Babies are particularly prone to heat rash because their sweat glands are immature and block easily. This often happens if they are bundled up too warmly or sleep in a hot room. To prevent it, dress your infant in lightweight, breathable layers and check their skin regularly to ensure they are not overheating. Avoid heavy ointments that might clog their delicate pores.
Can I use rich moisturising creams to heal my heat rash?
Using rich creams or thick ointments is actually a common mistake when dealing with heat rash. Since the root cause of this condition is blocked sweat glands, applying heavy, oil-based moisturisers can further clog your pores and trap even more sweat under the skin. It is much better to keep the area cool, dry, and clean, using only lightweight, soothing treatments like calamine lotion.
How can ScanSkinAI help me figure out if I have heat rash?
ScanSkinAI can analyze photos of your skin to help identify visual patterns commonly associated with heat rash, such as small red bumps in sweat-prone areas. However, it is important to remember that our tool is designed as a preliminary screening aid, not a diagnostic device. A doctor is always required to provide a definitive diagnosis and rule out other potential skin conditions or infections.
Medical References
Information on this page is sourced from and verified against reputable medical resources:
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Medical Disclaimer: This information is for educational purposes only and is not intended as medical advice. The content on this page should not be used to diagnose or treat any health problem. Always consult with a qualified healthcare professional for proper medical evaluation, diagnosis, and treatment of your condition.