Heat Rash 101: What Causes It and How to Get Rid of It Quickly

Singapore’s humidity is no joke. Step outside for five minutes, and you’ll have a drenched back and a resolution to ditch glowy makeup forever. But beyond the usual shine and slick, many of us face an even less glamorous warm-weather woe: heat rash.

If you’ve ever noticed clusters of tiny red bumps that sting or itch when the temperature spikes, you’re not alone. Whether it shows up after a gym session or from just walking around the city, heat rash is more common than you think.

Ahead, we break down what it really is, how to spot it, and the fastest ways to treat it.

What is a Heat Rash?

Heat rash, also known as miliaria or prickly heat, happens when sweat gets trapped under the skin, clogging your pores and causing inflammation. It typically occurs in hot, humid environments and can affect people of all ages.

“It’s caused by occlusion of the eccrine sweat gland. Sweat’s supposed to come out of this gland, but if you have something occluding the surface, it can block sweat, plug up the sweat gland, and lead to itchy, miserable bumps,” Board Certified Dermatologist Dr Andrea Suarez (better known as Dr Dray) explains.

Depending on the severity, the rash can range from mild irritation to more painful, inflamed bumps.

Heat Rash Symptoms to Look Out For

The signs of a heat rash can look a lot like other skin issues (think: acne or allergic reactions), but here’s how to tell them apart:

• Clusters of small red or pink bumps
• Itching or a prickling, stinging sensation
• Slight swelling or inflammation
• Rash appears in sweaty areas (neck, chest, back, armpits, face)
• In some cases, clear fluid-filled blisters may form

Heat rash is often triggered by sweating, tight clothing, or product buildup, so pay attention to when and where it crops up.

Types of Heat Rash

Here’s how you can identify the three types of heat rash:

Heat Rash on Face: Why It Happens and What to Do

A heat rash on your face can be especially frustrating, especially when it disrupts your skincare routine or makeup application.

The skin on your face is thinner and more sensitive, so clogged sweat glands (especially around the forehead, hairline, and cheeks) are more prone to inflammation.

Here’s what to do:

• Go makeup-free if you can, or opt for non-comedogenic, breathable formulas.
• Avoid heavy creams that could worsen congestion. Lightweight gel moisturisers or hydrating serums are ideal.
• Cleanse twice daily with a gentle, pH-balanced cleanser.
• Apply a cool compress to soothe inflammation and bring down the redness.

Heat Rash Treatment: How to Soothe It Fast

The good news? Most heat rashes are mild and can go away on their own, but if you want quicker relief, here’s how to treat it.

Tried-and-true treatment tips:

• Cool down: Step into air-conditioning or take a cold shower to help your skin regulate.
• Keep skin dry: Gently pat (not rub) your skin with a towel and avoid tight clothing.
• Use calming skincare: Look for ingredients like calamine, aloe vera, or chamomile to reduce itching and redness.
• Skip fragranced products: These can further irritate your already-sensitive skin.
• Avoid scratching: As tempting as it is, scratching can worsen the rash and cause infection.

How to Get Rid of Heat Rash Quickly

If you’re hoping to make it disappear yesterday, speed is all about prevention and swift action.

Here’s your game plan:

1. Remove the trigger: Get to a cooler place, change out of sweat-soaked clothes, and rinse off.
2. Apply anti-inflammatory treatments: Think aloe vera gel, calamine lotion, or over-the-counter hydrocortisone cream for itch relief.
3. Skip occlusive skincare: No heavy balms or oils until your skin clears up.
4. Hydrate and cool internally: Drink water, eat cooling foods like cucumber and watermelon, and let your body help out.

For facial flare-ups, stash a mini facial mist in your bag to cool down on the go.

Products to Calm a Heat Rash

Nature Republic Aloe Vera 92% Soothing Gel

Need a gentle hydrator that won’t clog pores? Reach for Nature Republic’s Aloe Vera 92% Soothing Gel. This best-seller contains 92% organic aloe vera and works double-duty as a calming gel mask or lightweight moisturiser – perfect for heat-stressed skin.

Nature Republic Aloe Vera 92% Soothing Gel retails for S$5.10 (300ml) on Hush.sg.

Snake Brand Prickly Heat Cooling Powder

This is a staple in many Asian households for good reason. The refreshing menthol-infused formula instantly soothes itching and absorbs moisture, ideal for keeping skin dry in our sticky climate.

Snake Brand Prickly Heat Cooling Powder retails for S$1.68 at FairPrice.

ICM Pharma Calamol Lotion

To keep itching at bay, the ICM Pharma Calamol Lotion is a great option. It’s formulated with 15% Calamine BP, offering cooling relief for prickly heat, bites, and sunburn without being too harsh on delicate skin.

ICM Pharma Calamol Lotion retails for S$7.30 (120ml) at Watsons. 

How Long Does Heat Rash Last?

Most cases will clear up within two to three days if managed properly. More stubborn rashes may last up to a week, especially if you’re repeatedly exposed to the same hot, humid conditions.

If your rash lingers longer or shows signs of infection (think: pus, extreme pain, or spreading redness), it’s time to see a doctor.

Related read: 17 Top Eczema Creams to Soothe and Hydrate Dry, Itchy, Sensitive Skin Fast