Dr Philippa Kaye On Hot Weather Rashes
At home or on holiday, hot weather rashes are unpleasant to deal with, but treatment can be simple and effective says Dr Philippa Kaye…
Dr Philippa Kaye
Nicolette was new to the surgery when she made contact with us.
She had completed an e-consultation after a weekend where the weather had turned warm and sunny. She wrote that she had developed an incredibly itchy rash on her chest after sitting out in the sun.
She also told us that she had got a similar rash whenever she had gone on a summer holiday and that sometimes it happened in the UK as well; often on her hands. She was planning a holiday and wanted to know what the rash was and what could be done about it. She attached photos of the rash, and the combination of the history Nicolette gave, and the appearance of the rash led me to diagnose her with polymorphic light eruption (PMLE), which we then treated. Rest assured she still booked her holiday!
What is PMLE?
PMLE is a rash which is related to exposure to sunlight, just as Nicolette described in her consultation. It is more common in women between 20 and 40 years old, and it tends to improve after the menopause.
The rash of PMLE is thought to be triggered by exposure to UVA light from the sun, which leads to an immune system reaction. PMLE can affect people of all skin types.
The word polymorphic means lots of shapes. PMLE is so called because the rash can look different in different people. In general, though, your rash will look the same on you each time. Often it looks like a rash made of small red spots, or tiny clear fluid-filled blisters on a background of red skin. Just as Nicolette mentioned, the rash can be extremely itchy, or feel painful or burning in nature. The rash of PMLE tends to affect areas which don’t generally get exposed to the sun, such as your chest or upper arms, but other parts of the body such as the hands can also be affected.
What causes PMLE?
PMLE occurs after exposure to strong sunlight, though the length of time needed for the rash to develop is not very long, even half an hour is long enough. The rash tends to develop within a few hours, and if you stay out of the sun the rash wil improve within a few days and does not leave scars.
Can you suffer from PMLE all year round?
People with PMLE often describe that as the spring and summer months progress, their symptoms improve. The skin becomes “hardened”, in that it gets used to being exposed to the sun. This means that symptoms tend to occur in earlier spring or summer, or on holiday. Each winter however the skin resets so the rash can occur when the sun comes out again!
What can I do to avoid PMLE?
If you can, try to prevent the rash of PMLE developing, so stay out of the sun, use a wide-brimmed hat to shade your face, wear long sleeves and use a broad protection sunscreen, with a high SPF factor and a high UVA star rating (out of five). Apply generously and reapply regularly! If the rash does develop again, try to stay out of the sun to prevent it from worsening.
How is PMLE treated?
PMLE is treated with a combination of antihistamine tablets for the itching and steroid creams. Low dose steroid creams are available over the counter but if this is insufficient then your GP may be able to prescribe higher strength steroid creams or ointments for a short period of time.
In some situations they may offer a short course of oral steroids. If you have very severe PMLE then your GP might refer you to a dermatologist who may consider phototherapy, UV light treatment for your skin.
Other summer rashes
PMLE is not the only rash which can occur when the weather gets hot! Heat rash (prickly heat/miliaria) is common due to a blockage of sweat ducts in the skin. This leads to the sweat seeping into the skin causing an itchy rash.
Avoid the heat and apply simple emollient soothing creams. The hot weather means you are more likely to sweat, and fungi like a moist, warm environment, so fungal infections are also more common, often in the groin or under the breasts. If you are concerned about a rash see your pharmacist or GP.
Advice given in this article and on the My Weekly website and magazines is not meant to replace personalised medical advice from your doctor. If you have any health concerns please see your doctor.
Article written on August 10, 2023; article reviewed and updated on August 20, 2024.
Each week we’ll ask Dr Philippa Kaye to talk about a prominent health issue, so look out for more articles in our health and wellbeing section in coming weeks. Read her advice on Ulcerative Colitis, Pre-diabetes, Skin Cancer, Allergies, Parkinson’s Disease, Shingles, Ovarian Cancer, Endometriosis, Long Covid and Ticks and Lyme Disease.
