Miliaria

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Introduction

Miliaria is a common skin condition caused by blocked sweat ducts. It is also known as heat rash, prickly heat or sweat rash.

Red, spotty heat rash or miliaria on the face, neck and chest of a newborn baby

Who gets it?

Infants and children are more likely to develop miliaria as they have underdeveloped sweat glands. Miliaria affects up to 1 in 10 newborn babies and is especially noticeable within the first week of life. Older children living in hot, humid or tropical environments can also develop miliaria. Miliaria can affect all age groups and ethnicities.

What causes it?

Sweating causes miliaria. When you sweat into a duct that is blocked, the duct will either fill up with sweat or rupture. This causes the skin surrounding the blocked or ruptured duct to become red and inflamed. The main reasons your child may develop miliaria are:

Immature sweat glands (in a newborn)
A hot and humid climate
Physical activity
Fever
Occlusion of skin with non-porous dressings or synthetic clothing on skin
Hospitalised or bedridden children

What does it look and feel like?

Miliaria will develop on areas of skin that have less hair growing such as the neck, chest and groin, and in skin folds such as the neck, groin and armpits.

Looks like…

Small, white or red bumps. Sometimes there might be blisters that break easily. These blisters may look like beads of sweat.
Small, red, flat spots
Pink or red skin may surround the bumps/dots

Feels like…

Itchy
Prickly
Warm

What tests might be needed?

Often no tests are needed to diagnose miliaria. Sometimes the doctor might want to perform a skin biopsy. To do this, a numbing liquid is placed under the skin at an area where a small sample of skin is to be removed. The skin is then looked at under a microscope to diagnose the condition.

A doctor might need to check that your child's skin isn’t infected by doing a swab which involves swiping a cotton bud over certain areas that have miliaria.

What treatments are available?

What can I do?

Keep your child in a cool environment and avoid hot, humid places where they are more likely to sweat
Keep your child in loose, cotton clothing, as tight clothing can make it worse
If your child's clothes become wet from sweating, remove them so they don’t irritate their skin
Avoid plastic covered mattresses
Avoid over swaddling your child with garments, especially babies
Avoid having them lying in bed for long periods
Shower them in cool running water

Medical therapies

Calamine lotion can be rubbed on the skin to ease the itchy sensation
Steroid creams and lotions can be rubbed on the skin to ease the itchy sensation
Antibiotics can be prescribed if your child's miliaria is infected

What happens after treatment?

The spots and redness will often disappear once your child is no longer hot and sweating. This may take a few days.
If your child's miliaria is more severe, it may take several weeks to resolve while the plug on the sweat ducts is slowly pushed off and new skin is formed.
If the miliaria is deep in the skin, some of the sweat glands may not function properly and your child will have excessive sweating in other non-affected areas.