Tiny blisters on your baby’s skin, could it be heat rash

Heat rash (miliaria) is a familiar term for many parents, probably because it crops up quite often. It can appear even in the newborn stage. We usually notice those tiny, fluid filled blisters on a baby’s chest, shoulders, back and armpits in summer. In most cases they do not cause discomfort, are not itchy and are not inflamed. They can look a bit like spots. Sometimes a red, itchy, inflamed version can occur on larger areas and in clusters.
Heat rash is harmless and can be prevented with a little care.

What does heat rash look like on a baby’s skin 

You will most often spot the small, fluid filled blisters while dressing your baby. If they appear on the face, you will see them even sooner. The area is usually skin coloured, which means there is no inflammation. It can also be red, which means there is. Depending on what you are seeing, there are two main types.

Miliaria crystallina, the milder form 

Tiny, clear fluid blisters appear close together on the skin, usually in larger patches on the body, especially in the armpits, on the back and chest. They are not inflamed, not red and not painful. If the blisters are scratched and burst, the fluid drains away.

These symptoms do not cause complaints for the child.
Miliaria crystallina develops due to overheating and settles quickly once the skin cools and the sweat ducts are no longer blocked. You can help by moving your baby to a cooler place or giving a gentle bath.

Miliaria rubra, when inflammation is present 

The rash can become inflamed, the skin itches and can be sore. It looks red and swollen and the blisters do not burst. Thankfully heat rash rarely progresses this far. For sweat ducts to become so blocked that the deeper skin layers are involved and sweat starts to spread there instead of reaching the surface, babies usually need to be in hot, tight, non breathable clothing for several days.

Inflammation develops in the blocked sweat glands, and the ducts can be damaged. If this meets the bacteria and salt in sweat, inflammation follows. Speak to your paediatrician if your baby’s skin is red and the itching or inflamed skin seems uncomfortable.

We try to dress babies in airy layers in summer, but it is easy to forget how warm it can get under the nappy. Pay attention to the constant warm, moist environment here as well. If you can, give some nappy free time and choose products that will not make the skin too hot.

What actually causes heat rash 

In babies, it is normal that thermoregulation is not yet fully mature. When sweat ducts become blocked, tiny spots and blisters appear, often in the skin folds and on other body areas.

This needs increased sweat gland activity and a temperature that is already too much for your baby. This is why careful observation is so important in summer. Once they get hot, heat rash can show up quickly.

How can you tell if your baby is too warm

Check at the nape of the neck by slipping your hand under their clothing. If the skin is sweaty or their hair is damp, they need fewer layers. Hands and feet on their own are not reliable guides, as they can often feel cool even when the body is warm.

A symptom that clears without treatment 

Yes. The non inflamed form, miliaria crystallina, clears on its own in babies and toddlers if you help the skin to breathe and avoid further sweating. Dress your baby in loose, airy clothing or let them be nappy free for a while when the temperature allows.

Treating inflamed blisters 

If the blisters do not settle, speak to your paediatrician, who can prescribe an appropriate medicated product.

Although the inflamed type can look worrying, it can still improve in a similar way. Medicines are not needed unless bacteria multiply significantly. Because this state can cause discomfort such as itching, burning or pain, ask your paediatrician for advice. If there are signs of infection, they will prescribe an antibiotic cream.

The right clothing really matters 

Some children are more prone to heat rash. Check them more often to make sure they are not too hot. In summer always consider the ambient temperature when dressing a baby. Choose baby clothes that allow the skin to breathe and do not trap heat. Natural fibres work well for this. Cotton and linen are popular, and bamboo is also a good choice.

LiaaBébé premium bamboo viscose babywear is highly breathable and very stretchy. This means your baby should not have to deal with discomfort while wearing our pieces. They are less likely to sweat, overheat or get chafed skin and can move freely in real comfort. That matters too.

What else can we do to prevent heat rash

Alongside avoiding overdressing, a bath can feel lovely in the summer heat, and some nappy free play can help too. These not only improve comfort and mood, they help keep skin clean and reduce overheating. Change nappies more often so skin does not get sweaty and soggy in a warm, moist environment. In summer, use extra thin disposables or well ventilated reusable nappies.

If your baby is in a pram or car seat, place a breathable muslin or a special seat liner underneath so their back does not get sweaty. In the car, air conditioning is essential in summer. Set it carefully with your baby’s needs in mind.

It is worth saying that there are no absolutely guaranteed prevention tricks. Even with care and thoughtful dressing, a few tiny blisters can still appear. The good news is they usually appear less often and on smaller areas. You may also find that while the rash was present at the start of summer, it did not return later in the warm months. Some children do not get it again at all.

Sun allergy can look similar 

Sun allergy is triggered by UV exposure. On exposed skin, itchy rashes can appear a few hours after sun, or 1–2 days later. This is usually an immunological response. True sun allergy is rare in children.

Sources:

NHS — Heat rash

NHS — Keeping your baby safe in the sun