Baby Heat Rash in Singapore: Causes and Care
Charles had heat rash across the back of his neck for most of his first March, and I spent a fortnight treating it as a skin problem before I understood it was a temperature problem.
Creams won't clear it while a baby is still hot. I tried three before I believed that. Once the baby cools down, it goes on its own, usually within a day or two and sometimes by the next morning.
Why is heat rash so common in Singapore?
Heat rash comes from blocked sweat ducts, and here a baby sweats all year. A baby's sweat ducts are small and immature, so they block easily. Sweat that can't get out collects just under the skin and makes the pinpoint bumps. Humidity above eighty per cent stops sweat evaporating even when it does get out, so this climate produces heat rash more or less all the time. Then there's the way we live. Most flats are air-conditioned in one room and not the others, so a baby moves between 24°C and 31°C several times a day. There's the walk to the MRT. There's the carrier, which is warm by design and presses fabric and an adult's body heat against her back. And there's a grandmother, or a mother-in-law, or in my case both, who worries the baby will catch cold in the aircon and adds a layer while you aren't looking.
None of this is anyone's fault. It's a hot country, a small body that doesn't cool well, and a grandmother who meant well.
How do I know it's heat rash and not something else?
The giveaway is that it follows the temperature. It shows up where she's hottest, after she's been hot, and it settles when she cools down. That's what sets it apart from the rashes it looks like.
It shows up as tiny clear or red pinpoint bumps, in the neck folds, the armpits, the groin, across the back and shoulders, and anywhere a strap or a waistband goes. It isn't usually very itchy in babies and it doesn't weep or crust.
| Looks like | Where | Tell | |
|---|---|---|---|
| Heat rash | Tiny clear or red pinpoint bumps | Neck, folds, back, shoulders | Follows heat; settles when cooled |
| Diaper rash | Diffuse pink, creases spared | Under the nappy only | Follows the nappy, not the weather |
| Eczema | Dry, scaly, itchy | Cheeks, elbows, knees | Persists regardless of temperature |
| Infection | Pustules, weeping, crusting | Anywhere | Needs a doctor, not cooling |
If it is under the nappy
What settles heat rash at home
All of this is free, and the first step does most of the work.
- Cool her down with air-conditioning, a fan that moves air past her without blowing straight at her, or simply fewer clothes. Cooling is the treatment. Everything else just helps.
- Take a layer off, then think about taking off another. One thin layer is enough indoors here for most of the year.
- A tepid bath or a wipe-down with a soft damp cloth, then air dry. Don't rub the skin dry, because friction on blocked ducts makes it worse.
- Leave the affected skin open to the air where you can. Nappy off on a towel for twenty minutes is very effective for rash in the groin.
- Loose, thin, breathable cotton or bamboo, with nothing tight over the rash.
- Keep the folds dry. In this humidity the neck, wrists, thighs and backs of the knees stay damp, so dry them properly after every bath and after any messy feed.
What to skip: thick creams, ointments and barrier balms, which block the ducts even more and are the most common mistake. Talcum powder, which she can breathe in and which doesn't help. Anything medicated, unless you've been told to use it. I'd guess we spent S$60 on creams that first March. I haven't checked the receipts, and I don't want to.
Which fabrics make a difference
I design clothing for a living, so here's the fabric part in detail.
What matters is whether the fabric draws moisture off the skin and lets air through. Thin bamboo viscose and cotton muslin both do this well. Thick jersey holds heat against the body. Polyester and most synthetic blends hold in both heat and moisture, and they're everywhere in cheap babywear because they're cheap.
Then look at how the garment is made, which almost nobody checks. A raised seam under a carrier strap, an elastic waistband in a fold, a heavy printed panel across the chest, a bib with a plastic backing: each one makes a small hot patch, and heat rash starts in small hot patches. If the rash keeps coming back in the same spot, look at what sits on that spot. In our flat it was the popper strip on one brand of bodysuit, and I only found it by holding the garment up against where the rash was.
Mentioned above
When to take your baby to a doctor
Heat rash itself almost never needs a doctor. These do, and none of them is heat rash.
- Pustules, yellow crusting, weeping, or skin that is hot, spreading and tender, which suggests infection.
- A fever alongside the rash, and any temperature of 38°C or above in a baby under three months, which is urgent regardless of the rash.
- A rash that doesn't settle within two or three days of proper cooling.
- A baby who's unusually floppy, drowsy, refusing feeds, or has had noticeably fewer wet nappies, which points at heat illness and needs same-day attention.
- Any rash that doesn't fade when you press a glass against it, which needs emergency care immediately.
- Dry, scaly, persistently itchy patches that don't change with the temperature, which is a different condition and needs a proper diagnosis.
Sources: NHS: Heat rash (prickly heat) · HealthHub: Ministry of Health Singapore
This guide is general information, written to help you understand a topic and ask better questions. It is not medical advice and does not replace your own doctor, midwife or paediatrician. Anything that worries you about your baby belongs with them.
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