Summer sun rashes. How they occur and how to deal with them
The sunny weather may have encouraged you to finally get outdoors after a long winter.
But after spending time in the sun you may be horrified to discover an angry red rash instead of a healthy golden glow. Sun rashes have a variety of causes. Sunlight by itself can cause skin rashes in susceptible people. But in others, sunlight can make them sensitive to plants, medicines and fragrances, including sunscreens. If you develop a sun rash, you may have to do a little detective work to find out what's causing it.
Polymorphic light eruption
PLE is often confused with prickly heat (see below). Triggered by sunlight, the rash is thought to be linked to the body's immune response. As little as 20 minutes exposure to the sun can result in an itchy, red rash, which usually appears on skin which has been kept under wraps during the winter months.
PLE often makes its first appearance in the spring, but disappears after a week or so if the skin is kept covered from the sun. The rash generally gets worse and spreads if the skin continues to be exposed to the sun.
PLE is more common in women than men, in people with fair skins, and usually affects those under the age of 30.
The rash is triggered by both UVB and UVB radiation in sunlight. Try to stay in the shade when possible, use a broad spectrum sunscreen which protects against both UVA and UVB and has a high sun protection factor (SPF), and wear loose long sleeved clothing.
If the rash is severe, your doctor may prescribe steroids or refer you to a dermatology clinic for ultraviolet desensitisation treatment.
Also known as heat rash or miliaria, this itchy red rash gives a prickly sensation on the skin. It occurs if you sweat more than usual and glands become blocked, so that sweat is trapped under the skin.
Tiny bumps or blisters appear on red skin, often on parts of the body where sweat collects, such as the armpits, groin, waist, chest and insides of the upper arms.
Young children and obese people are more prone to prickly heat, but anyone can get it.
Try to stay as cool as possible. Wear loose cotton clothing and take regular cool showers. Calamine lotion may help to soothe the affected areas. Hydrocortisone creams may also provide some relief from itching, but shouldn't be used on your face. Speak to your doctor or pharmacist about these.
Drug-induced photosensitivity
Many drugs can make your skin more sensitive to sunlight, including some of the drugs used to treat high blood pressure, antihistamines, antibiotics, anti-depressants and nonsteroidal anti-inflammatories.
The combination of drugs and sunlight can cause two types of reaction. The first type develops rapidly and looks like a bad case of sunburn, found only on areas of the skin exposed to the sun - face, neck, arms, lower legs, back of hands and feet.
The second type, an itchy, red rash resembling eczema, is caused by an allergic reaction and develops within one to three days on sun-exposed skin, but can also spread to other areas.
If you are taking medication and develop a rash after being in the sun, you should speak to your doctor. They may be able to recommend alternative medication.
Plants, chemicals and the sun
Contact with chemical compounds found in plants, grasses, sunscreens, insecticides and various toiletries, combined with sun exposure can also cause severe skin reactions.
Common culprits include parsnips, celery, parsley, dill, fennel, limes and lemons, which contain chemicals called furocoumarins, naturally occurring phototoxins which, along with the sun, trigger the reaction.
In the countryside, coming into contact with the giant hogweed, cow parsley or angelica can result in a red, blistering rash on sun-exposed skin, usually within 24 hours.
Bergamot and musk oils in fragrances and chemicals have a similar effect in people who are susceptible. Similarly, chemicals used in sunscreens to absorb UV radiation can also cause this.
Identifying what the trigger for this type of rash is key. Keep a record of where and when your symptoms develop and take this to your doctor. Try using sunscreens which act by blocking UV radiation or ones designed for sensitive skin instead.
This is a rare condition where people develop hives within minutes of coming into contact with the sun. Resembling nettle rash, the itchy red patches of skin may also become swollen and soon disappear once the person has gone indoors out of the sunlight.
The rash often develops on areas of the skin usually shielded from the sun, such as the back. Other areas of the body which are constantly in the sun, such as the face or backs of the hands may be unaffected or only slightly so.
Solar urticaria is more common in women than men, can occur at any age, but most develop it before the age of 40. Although unclear, it is thought to be caused by an allergic reaction.
Exposing large areas of the body to sunlight - e.g. outdoor swimming - can lead to light headedness, headaches, nausea and vomiting.
People with solar urticaria are usually referred to a dermatology clinic where they will are advised about what lifestyle changes they should make.
These generally include wearing sun protective clothing, regularly using sunscreens and keeping out of the sun when it is most intense.
Anti-histamines may help reduce the rash and itching. Some patients may undergo ultraviolet desensitisation treatment.
