Sweat rash on the ankles: what helps?

What does heat rash look like?

Heat rash, also called miliaria or prickly heat, develops when blocked sweat glands trap sweat in the skin. Look for small raised spots, an itchy or prickly feeling and mild swelling. Some spots contain fluid. The rash can look red on white skin or grey or white on brown or black skin. It is not contagious.1

Sweating cools your body, and sweating more during hot weather or exercise is normal. Hot, humid conditions can provoke heat rash, but can also cause chafing, softened damp skin and bacterial or fungal infections. The fact that an ankle rash appeared after sweating does not identify its cause.45

How to calm suspected heat rash

1. 1Move somewhere cooler and less humid, and choose loose cotton clothing rather than tight layers.
2. 2Take a cool bath or shower. Avoid perfumed shower gels and creams.
3. 3Apply a cool damp cloth, or an ice pack wrapped in a towel, for up to 20 minutes.
4. 4Pat or tap itchy skin instead of scratching it. Use lightweight bedding at night to keep the skin cool.

Heat rash usually improves on its own within a few days. If itching is troublesome, a pharmacist can help choose a treatment such as calamine lotion, antihistamine tablets or hydrocortisone cream. For children under 10, get a doctor's advice before using hydrocortisone. See a GP if cooling the skin does not lead to improvement after a few days.1

Could socks or shoes be causing it?

Shoes and socks can cause contact dermatitis, an irritated or allergic skin reaction. Possible triggers include rubber, leather, fabrics, dyes, metal and glue. A reaction can start with new footwear or items you have worn before. If the rash follows the area a sock or shoe touches, try avoiding the suspected item and see whether the rash clears. An itchy rash beneath an anklet is another reason to consider contact dermatitis.2

Foot creams, scrubs, powders and deodorants belong on the suspect list too, so the bathroom shelf does not get diplomatic immunity. Stop nonprescription cosmetic products you suspect are triggering the rash. For a suspected reaction to a prescription product, contact the prescribing doctor. A dermatologist can help identify a trigger when avoiding suspected items does not resolve the problem.2

Should you put moisturizer on it?

The cause matters. For a child's heat rash, avoid creams and ointments that keep the skin warmer and block pores; powders are unlikely to help. Dry lower leg dermatitis has different care needs, including simple emollients and cleansers without soap. A dry, scaly patch should not automatically get the same treatment as prickly heat.67

Choose products labelled "fragrance free" if fragrance is a suspected trigger. "Unscented" can mean fragrance has been covered up, which is a naming solution rather than an ingredient removal service.2

When should an ankle rash be checked?

Persistent ankle swelling and discoloured skin, especially over enlarged veins, need assessment rather than repeated heat rash treatment. Stasis dermatitis is eczema caused by poor blood flow and often starts near the ankles. If you already have venous insufficiency, meaning poor blood return from the legs, new skin changes are a reason to see a dermatologist.3

Seek medical assessment for painful, red, swollen skin with oozing, open sores or pus, which can indicate infection. For a child, contact their clinician if the rash comes with fever or unexplained symptoms, blisters, significant scratching, or no improvement after three days of home care. Contact a clinician about a rash in a baby younger than three months.56