Prickly heat occurs when the body's sweat glands become blocked. Excessive sweating can cause sweat to become trapped beneath your skin, leading to skin irritation and a red rash.
If you sweat excessively, it is easier for dead skin cells and bacteria to collect in your sweat glands.
If your sweat glands become blocked, sweat will be trapped underneath your skin in tiny swollen pockets. It will also seep into the nearby tissue and irritate your skin.
When the pockets burst and release sweat, it causes a stinging and prickling sensation (prickly heat).
Risk factors
You are more at risk of developing prickly heat if you're in a hot climate where you sweat more than usual.
The following also increase your risk:
- illness and immobility – long periods of time spent in bed can make you sweat more, particularly if you have warm bedding
- wearing too much clothing, particularly in the winter
- sitting too close to a fire or heater
