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Dr. Chrysoula I. Liakou MD, PhD
- Treated online: Yes. Heat rash is recognised by how it looks, and a doctor can assess it on camera.
- What it looks like: small raised spots, 2 to 4 mm across, that itch or prickle; red on white skin, and grey or white on brown or black skin.
- Usual course: it usually clears within a few days once the skin is kept cool, often within a day or two of moving somewhere cooler.
- What helps: cool showers, loose cotton clothing, and calamine lotion or an antihistamine tablet for the itch.
- Emergency: call 112 for a rash that does not fade when you press a glass against it, or a rash with confusion or fainting in the heat.
Do not book a video appointment if a rash comes with a fever and does not fade when you press the side of a clear glass against it, or if someone in the heat becomes confused, faints or has hot skin that has stopped sweating. These need emergency care: call 112.
Can an online doctor treat heat rash?
Yes. Heat rash is recognised by how it looks and when it appeared, and both work by video. The doctor looks at the rash on camera, asks about the heat, clothing and sweating that came before it, and checks for infection and for rashes that need a different treatment. Most heat rash settles with cooling and simple care.
How an online consultation helps with heat rash
- The rash seen on camera: The doctor looks at the size and spread of the spots, and at how they look on your skin tone.
- Other summer rashes ruled out: Sun allergy, hives, insect bites and skin infections can look similar, and each is treated differently.
- Infection checked: Spots that fill with pus, spreading redness or a fever can mean a bacterial infection that needs treatment.
- Relief that suits you: The doctor checks your other medicines and conditions before suggesting anything for the itch.
What the doctor checks in an online heat rash consultation
The consultation follows a fixed order, and the warning signs come first. The doctor asks about:
- Warning signs: a fever, feeling unwell, confusion, or a rash that does not fade under a glass.
- The rash: when it started, where it is, whether it itches or prickles, and whether any spots contain fluid or pus.
- The setting: heat and humidity, exercise, tight or synthetic clothing, and how much you sweat.
- What you have tried: creams, sprays or tablets, and whether they helped.
- Your skin and medicines: skin conditions such as eczema, and the medicines you take.
Before the call, cool down for a while, and find good light so the doctor can see the rash clearly.
What is heat rash?
Heat rash, also called prickly heat or miliaria, happens when sweat glands become blocked. The trapped sweat cannot reach the surface of the skin, and it causes small, itchy spots. Heat rash is uncomfortable but usually harmless, and it cannot be passed on to other people.
It is common in people who arrive from a cooler climate during hot, humid weather, and it can appear within days of arrival. Hard exercise, a fever, sunburn, long periods in bed, and tight, heavy or synthetic clothing that traps sweat all make it more likely, and so do thick creams that block the pores and medicines that increase sweating.
Types of heat rash
Swipe sideways to compare →
| Type | What it looks like | Where it appears |
|---|---|---|
| Miliaria crystallina | Tiny clear blisters, 1 to 2 mm, that break easily, without redness or itch | Head, neck and upper body |
| Miliaria rubra (prickly heat) | Red, itchy or prickly spots, 2 to 4 mm, the most common type | Upper back and chest, neck, scalp and skin folds, especially where clothing rubs |
| Miliaria pustulosa | Prickly heat spots that fill with pus | The same areas as prickly heat |
| Miliaria profunda | Firm, skin-coloured bumps after repeated prickly heat; rare | Body, arms and legs |
Heat rash symptoms
Heat rash symptoms are often the same in adults and children:
- small raised spots, 2 to 4 mm across
- an itchy, prickly or stinging feeling
- mild swelling
- spots that contain clear fluid, in some cases
- a red rash on white skin; on brown or black skin it can be harder to see, and may look grey or white
It can appear anywhere and spread. In adults it is most common in skin folds and where clothing rubs: the neck, upper chest and back, armpits, under the breasts, the waist, the groin and the elbow creases. A few heat rash spots can fill with pus, and a rash that becomes more painful, oozes or comes with a fever may be infected.
Is heat rash itchy? Usually. Prickly heat itches or prickles, sometimes intensely, but the mildest type, tiny clear blisters, neither itches nor hurts. Heat rash heals without scarring, although on brown or black skin it can leave lighter or darker patches that fade over weeks or months.
Heat rash or something else?
Sun allergy, hives, insect bites, folliculitis, sunburn and intertrigo can all be mistaken for heat rash. Heat rash is the likely cause when tiny spots appear where you sweat or clothing rubs, in hot and humid weather, and fade once the skin cools. These patterns help tell them apart:
Swipe sideways to compare →
| Rash | What points to it | Read more |
|---|---|---|
| Heat rash | Tiny itchy or prickly spots where you sweat, in hot and humid weather | This page |
| Sun allergy | An itchy rash on sun-exposed skin, hours to days after strong sun, often early in the summer or on holiday | Sun allergy |
| Hives | Raised, itchy welts that come and go within hours, anywhere on the body | Hives |
| Insect bites | Separate itchy bumps on uncovered skin, sometimes in a line or a cluster | Mosquito bites Bed bug bites |
| Folliculitis | Spots centred on hairs, sometimes with pus, after shaving, sweating or a hot tub | Folliculitis |
| Sunburn | Hot, red, painful skin in the areas the sun reached | Sunburn |
| Intertrigo | Red, sore, sometimes moist or cracked skin inside skin folds, from heat, moisture and rubbing | Intertrigo |
How to treat heat rash
The aim is to cool the skin and stop the sweating that blocks the glands. Most heat rash clears within a day or two of moving somewhere cooler.
Do
- Keep your skin cool: wear loose cotton clothing, use light bedding, and sleep in a cool, well-aired room or with air conditioning.
- Take cool baths or showers, and dry the skin gently.
- Drink plenty of fluids.
- Apply something cold, such as a damp cloth or an ice pack wrapped in a tea towel, for up to 20 minutes.
- Tap or pat the rash instead of scratching it.
- Keep skin folds dry with an absorbent powder, such as cornflour-based powder.
- Change out of sweaty or wet clothes as soon as you can.
Don’t
- use perfumed shower gels, soaps or creams
- wear tight or heavy clothing over the rash
- cover the rash with thick, greasy creams that hold in heat and sweat
How to prevent heat rash on holiday
Heat rash comes back whenever the skin overheats and sweats heavily, so prevention is about staying cool:
- Choose loose, breathable clothes, and change out of sweaty clothes after exercise.
- Plan exercise and long walks for the cooler early morning and evening.
- Sleep in a cool, ventilated room, with air conditioning or a fan if you can.
- Take a cool shower after a hot day or a long journey.
- Use light, non-greasy sunscreen and moisturisers.
To see how hot it is where you are staying, check the daily heat scores for European cities in the Climate Health Index. Other holiday health problems are covered on the travel illnesses page.
Which heat rash treatment might the doctor recommend?
Treatment depends on how widespread and itchy the rash is, and whether it is infected. This is the framework the doctors use, in line with NHS and dermatology guidance.
Swipe sideways to compare →
| What you have | Likely first step | Suitable for online care? | When in-person care is needed |
|---|---|---|---|
| A mild, prickly rash | Cooling, loose clothing, calamine lotion | Yes | Not usually needed |
| A very itchy rash that stops you sleeping | An antihistamine tablet, or a mild steroid cream for a few days | Yes | Not usually needed |
| A rash that has not improved after a few days | A review of the diagnosis: another rash may be the cause | Yes | If the doctor needs to examine it in person |
| Spots with pus, spreading redness or a fever | Treatment for a bacterial skin infection | Yes | If you feel very unwell |
| A rash that does not fade under a glass, with a fever | Emergency assessment | No | Call 112 now |
Not sure the rash is heat rash? A doctor can tell you in one consultation.
See available times →Treatment options for heat rash
What you can do yourself
- Cool the skin with showers, cool compresses and air conditioning or a fan.
- Use calamine lotion to ease the itch. It can dry the skin, so a light, unperfumed moisturiser afterwards helps.
- Ask a pharmacist about antihistamine tablets for the itch.
- Ask a pharmacist about hydrocortisone cream for a very itchy patch, and use it only for a few days.
Prescription treatment
A prescription is never issued without a consultation. For a stubborn or very itchy rash, the doctor may suggest a steroid cream for a short time. If spots have become infected, the doctor can prescribe an antiseptic or antibiotic treatment. If the doctor prescribes, use the prescription at a pharmacy near you.
What does not help
Heavy creams and ointments hold in heat and sweat and can make heat rash worse. Scratching breaks the skin and lets bacteria in. Staying in the heat while treating the rash with creams alone rarely works: the skin needs to cool down.
Special situations
Heat rash with feeling unwell
Heat rash itself is harmless, but the heat that causes it can also cause heat exhaustion. Dizziness, a headache, nausea, cramps or heavy sweating with pale, clammy skin mean you need to cool down and drink straight away. Heat rash over a large area of skin can stop it sweating properly, which raises the risk of heatstroke.
Heat rash that keeps coming back
Repeated prickly heat in the same areas is a sign that those areas overheat and sweat heavily. Lighter clothing, more time in the shade and a cooler bedroom usually help. If the rash keeps returning despite this, the doctor reviews whether another skin condition is involved. See a doctor if the rash covers a large area, looks different from usual, or keeps coming back.
Eczema and other skin conditions
Sweat irritates skin that is already inflamed. If you have eczema, a flare in hot weather can look like heat rash, and the treatment is different.
Pregnancy
Pregnancy makes you feel the heat more. The same cooling measures work, and the doctor checks that any cream or tablet suggested is suitable in pregnancy.
Children
Mobi Doctor consultations are for adults aged 18 and over. A child who is unwell needs a paediatrician or a local doctor in person, and emergency signs in a child mean 112.
When heat rash is treated online, and when you need in-person care
Treated online: heat rash and prickly heat, itchy rashes in hot weather, rashes that have not improved after a few days, and mild skin infections in a heat rash.
In-person care: a rash with a fever that does not fade under a glass, a rash with signs of heatstroke, and a spreading skin infection in someone who is very unwell.
When to get in-person care
Call 112 or go to an emergency department now for:
- a rash that does not fade when you press the side of a clear glass firmly against it
- a rash with a fever, a stiff neck, a severe headache or confusion
- confusion, fainting or hot skin that has stopped sweating after time in the heat
- swelling of the lips, mouth or throat, or difficulty breathing
Get medical advice the same day for:
- spots that fill with pus, spreading redness, or a rash that becomes hot and painful
- a rash with a high temperature, or feeling hot, cold and shivery
- a rash that spreads quickly or blisters
How Mobi Doctor works
- Book a time that suits you: daily 7am–11pm CEST. You can see a doctor over video, usually within 15 minutes. No subscription, and the exact price is shown before you pay.
- Speak to a licensed doctor about the rash: show it on camera in good light, and say when it appeared and what the weather and your clothing were like.
- Leave with a plan: what to do, what to take and for how long, and which signs mean you should be seen in person. If the doctor prescribes, use the prescription at a pharmacy near you.
No sign-up needed
Not sure it’s heat rash? Tick every symptom you have to see each condition page that mentions it. It finds the right page, not a diagnosis: a doctor gives you that on a video call.
Tap the body — an area or a point — to browse symptoms anywhere
Similar symptoms, different condition? Sun allergy can start the same way. Compare them, or look up any other symptom in the full symptom checker.
Frequently asked questions about heat rash
What does heat rash look like?
Heat rash is a patch of small raised spots, 2 to 4 mm across, that itch or prickle. On white skin the spots are red. On brown or black skin they can be harder to see and may look grey or white. Some spots contain clear fluid.
How long does heat rash last?
Heat rash usually gets better on its own within a few days. Once the skin is kept cool, most cases clear within a day or two. See a doctor if it has not improved after a few days.
What is the fastest way to get rid of heat rash at home?
Cool the skin down: take a cool shower, wear loose cotton clothing, and sleep in a cool room. Heat rash starts to settle as soon as the skin cools, and most clears within a day or two of moving somewhere cooler. Calamine lotion or an antihistamine tablet eases the itch. Creams alone rarely work while the skin is still hot and sweating.
What causes heat rash?
Heat rash is caused by blocked sweat ducts. When sweat cannot reach the surface, it is trapped under the skin and causes small, itchy spots. Hot, humid weather, hard exercise, a fever, tight or synthetic clothing, thick creams and some medicines that increase sweating all make it more likely.
Is heat rash itchy?
Usually. Prickly heat, the most common type of heat rash, itches or prickles, sometimes intensely. The mildest type, tiny clear blisters that break easily, does not itch or hurt.
How do I tell if my rash is heat rash?
Heat rash is a patch of tiny spots, 2 to 4 mm across, that appears in hot, humid weather where you sweat or clothing rubs, prickles or itches, and starts to fade within a day or two of cooling down. A rash on sun-exposed skin, welts that move around, or spots with a fever point to something else.
Is prickly heat the same as heat rash?
Yes. Prickly heat is the common name for miliaria rubra, the most common type of heat rash. It is named after the prickling or stinging feeling it causes.
Is heat rash contagious?
No. Heat rash is caused by blocked sweat glands, not by an infection, so it cannot be passed on to other people by touch, towels or bedding, and a child and a parent with it at the same time have simply shared the same hot room. A rash that spreads from person to person, blisters or crusts is something else and worth a consultation.
Can heat rash be serious?
Heat rash itself is harmless, but spots with pus, spreading redness or a fever can mean infection. A rash that does not fade under a glass, or a rash with confusion or fainting in the heat, needs 112.
Why do I get heat rash on holiday?
Skin used to a cooler climate is not adjusted to heat and humidity, so sweat glands block more easily and heat rash appears in the first days of a hot holiday. Tight or synthetic clothing, exercise in the heat and a hot bedroom make it more likely.
Is heat rash the same as a sun allergy?
No. Heat rash comes from sweat and appears where you sweat, even in the shade. A sun allergy, polymorphic light eruption, is a reaction to sunlight and appears on sun-exposed skin hours or days after strong sun.
Can an online doctor treat heat rash?
Yes. A doctor can look at the rash on camera, tell it apart from other summer rashes, and advise on cooling and soothing the skin. If the rash is infected or very itchy, the doctor can prescribe treatment after the consultation.
- Heat rash (prickly heat), NHS, National Health Service (UK), reviewed 9 May 2024.
- Miliaria, DermNet, New Zealand, updated September 2020.
- Heat rash: symptoms and causes, Mayo Clinic (US), updated 6 May 2022.
- Heat rash, healthdirect Australia, reviewed September 2025.
- Intertrigo, DermNet, New Zealand, updated 2026.
- Heat exhaustion and heatstroke, NHS, National Health Service (UK), reviewed 28 May 2026.
- Meningitis, NHS, National Health Service (UK), reviewed 12 June 2026.
This page is for information only and is not a substitute for a medical consultation. Guideline links are provided for transparency; treatment decisions are made with your doctor.
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