Heat Rash – Prevention Tips for Heat Rash

During the early months of World War II, American troops battling for the islands of the South Pacific were also doing battle with an annoying rash known to doctors as miliaria and to the rest of us as ‘heat rash’ or ‘prickly heat’. The intense burning and itching sensation of prickly heat is caused by a blockage of the sweat ducts. Strained by intense heat and humidity, the body’s evaporative cooling system breaks down, and instead of being exuded through the pores, sweat becomes trapped beneath the skin, resulting in a rash that feels like its name.

Dr Robert L. Stem, writing in the Journal of the American Medical Association not long after the war, reported his attempts to alleviate the disorder among the Pacific troops with ‘all the available lotions and medicaments of possible aid, changes of clothes and soaps,’ multiple vitamins, and vitamins A and D, all of which had ‘no noticeable effects’. But when he tried vitamin C, in doses of from 300 to 500 mg daily, it gave ‘dramatic relief to most patients. The itching cleared and the rash subsided, usually within half an hour, the effects lasting 6 to 24 hours.’

The power of vitamin C against the pain of prickly heat was demonstrated in a more controlled study carried out in Singapore by dermatologist T. C. Hindson, of the British Military Hospital there. It began with one of those happy accidents that the history of science is so full of. An Australian Air Force officer, troubled by a rash in his groin that had resisted all medication for a year, told the doctor that it suddenly cleared up in the course of a week when he caught a cold and started taking 1 g of vitamin C a day.

Intrigued by this and the results of other exploratory tests, Dr Hindson set up a study using 30 children who had been plagued by prickly heat for at least eight continuous weeks prior to the test. Half the youngsters were given a placebo and the other half vitamin C. In order to ensure that he wouldn’t bias the results, Dr Hindson himself did not know who was getting which. Only the hospital pharmacist knew.

After two weeks, the rash had disappeared completely on ten of the 15 children receiving vitamin C. Four others showed improvement and one remained unchanged. By contrast, nine youngsters in the placebo group showed no change and two had got worse. The rash had either cleared up or improved in the other four.

The 11 children in the placebo group whose prickly heat had either shown no improvement or had actually worsened were then given vitamin C and checked after two more weeks. The rash had cleared completely in six children and improved in the other five.

Admitting that the exact mechanism at work remained unclear, Dr Hindson concluded the ‘ascorbic acid [vitamin C], when given in high doses, is effective in the treatment and prevention of prickly heat.’ He also noted one of the vitamin’s greatest advantages: ‘No unwanted side-effects have been recorded from such doses to date’ (Lancet).

Air-conditioned offices an work areas in muggy climates have made heat rash almost obsolete, but for those who still suffer from this condition, beauty writer Virginia Castleton recommends tea made from raspberry leaves, which can soothe and have a calming effect when used as a light wash. Elder flowers are also soothing for heat rash. Like raspberry lotion, they produce the best effects when applied immediately after towelling dry following a cool shower. You might find additional relief by applying a dusting of cornstarch or powdered white clay following the lotion.


Avoid overdressing.

Allow Skin to breathe

Avoid heavy moisturizers. Tender newborn skin tends to be dry and in need of moisturizing. But heavy, oil-based creams can be a problem. ‘Moisturize with a light, water-based lotion instead.