Red, itchy bumps on the neck, chest or back could be heat rash, but a range of other summer skin conditions can look very similar. Dr Alison Grimston, a GP, functional medicine doctor and head of women's health at Dr Finlay's Private Practice, spoke to Camilla Foster about the six most common rashes seen in warmer months, their triggers and the best ways to treat them.
Heat rash: blocked sweat ducts
"Heat rash is related to blocked sweat ducts, which cause small, itchy red bumps that are usually on the neck, chest and back," says Grimston. The condition occurs when sweat becomes trapped beneath the skin, often during hot, humid weather or after vigorous activity. It typically clears up once the skin cools down.
"The best way to manage a heat rash is to keep cool, wear loose clothing and have cool showers. It should usually settle on its own," she advises. Avoiding heavy moisturisers and allowing the skin to breathe can also help prevent blocked ducts.
Polymorphic light eruption: a sun allergy
Polymorphic light eruption (PLE) is often mistaken for heat rash because both produce itchy, red bumps, but the cause is entirely different. "Some people have a sun allergy called polymorphic light eruption. This often appears when you go on your first sunny holiday or in spring or early summer," says Grimston.
According to the NHS website, the rash may feature small raised spots or blisters, present as larger blotchy patches, feel itchy or produce a burning sensation, and appear red or pink in colour. "It usually occurs on the chest, arms and shoulders – anywhere that's exposed to the sun," says Grimston.
Prevention is key. "Don't spend all your first day on holiday in the sun and wear loose cotton clothing," she advises. SPF creams and gradual sun exposure are the most effective methods of prevention, while a pharmacist can recommend emollients and antihistamines for symptom relief, according to the NHS.
Contact dermatitis: triggered by summer products
Contact dermatitis is a form of eczema triggered by contact with a specific substance, says the NHS. In summer, common culprits include sunscreens, fragrances and pool chemicals. "Summer triggers can include sunscreens, fragrances and chemicals in a swimming pool," says Grimston.
Symptoms range from mild redness and irritation to cracked skin, fluid-filled blisters, intense itching and a stinging sensation, according to the NHS. The condition usually improves once the offending substance is identified and avoided. "Read the ingredients on sunscreens and try to use as natural a sunscreen as possible. Emollients can also help, and sometimes you might need a mild steroid cream to help it to settle," recommends Grimston.
Insect bites: raised red bumps with local swelling
Warmer weather draws people outdoors – and brings them into contact with mosquitoes, midges, horseflies, wasps and bees. "Insect bites usually present in a raised, red, itchy bump that has local swelling and warmth around the bite, and occasionally blistering," says Grimston.
To treat a bite, the GP advises cleaning the area with soap and water and applying a cold compress for 10 to 20 minutes. "Avoid scratching as that can damage the skin and increase the risk of secondary infection. Oral antihistamines can help if itching is troublesome, and a mild topical hydrocortisone cream, which you can buy over the counter, can help reduce inflammation," she explains.
Swimmer's itch: a parasite reaction
Swimmer's itch, also called cercarial dermatitis, is an allergic skin reaction caused by tiny parasites called cercariae, released by certain freshwater snails. "These parasites normally infect birds and can't survive in humans, but they can penetrate the skin's outer layer and trigger an immune response," explains Grimston.
Symptoms include tingling or burning shortly after leaving the water, itchy red spots or small raised bumps, and occasionally tiny blisters. "It usually develops within hours and settles over several days," she says.
Showering after a swim, drying thoroughly with a towel after exiting fresh water, and staying away from lakes known to be affected during outbreaks can help prevent the condition. "Treatment options include cool compresses, emollients to soothe the skin, oral antihistamines for the itch and a mild topical steroid cream if needed," says Grimston.
Intertrigo: friction and moisture
Intertrigo occurs when skin rubs against skin, causing inflammation. "It's common under the breasts, in the groin and between abdominal folds. It can also occur in the armpits, between the buttocks, between the toes and even inside the belly button," says Grimston.
Summer makes it worse. "In the summer, you've got heat, sweating, friction plus reduced airflow, and that damages the skin barrier, especially if it's staying damp, which is very bad for the skin and can make it macerate or get compromised. This can lead to candida overgrowth, which is the fungus that causes thrush, and it can also cause proliferation of bacteria, so you can often get a secondary bacterial infection, where it gets even worse," she explains.
Symptoms include a red rash, burning, itching or soreness, and occasionally cracking. "If there's a secondary bacterial infection, you may get an unpleasant smell," she adds. Grimston stresses keeping the affected area cool, clean and dry. "You need to wear loose cotton clothes where possible and dry carefully after showering. I usually recommend a topical antifungal cream such as Daktarin. If there's a bacterial infection, you may need antibiotics."
When to seek medical advice
Not every rash can be treated at home. "If a rash is spreading, is very painful, is associated with fever, or simply isn't improving after a week or two, it's worth seeking medical advice rather than just trying another cream," says Grimston. "The skin likes to be clean, cool, and dry and treating the underlying cause is just as important as treating the rash. If a rash keeps coming back, it's worth asking whether there's an underlying condition such as diabetes, pre-diabetes or eczema."
