The sunbathing season, which is always greatly anticipated by Latvians who have grown weary of the grey skies, is just around the corner. This year, travelling abroad is risky, but it will allow us to enjoy Latvia’s sunshine. Surely, it sounds very beautiful and romantic, but not everyone has such a good relationship with the sun.
For a variety of reasons – explainable or not, some of us should not be exposed to direct sunlight. Instead of an attractive, bronze-coloured tan, one might end up with a sunburn to remember this summer by.
Fair-skinned people have known sunburns from childhood. They know that they should take special care when exposed to the sun. However, they are not the only ones that may be affected by direct sunlight. A completely healthy person can also become sensitive to the sun and be harmed by it instead of deriving pleasure from it. This happens due to chemical photosensitivity. Photosensitivity describes increased sensitivity to light caused by certain chemicals.
Phototoxic effects of the sun on the skin may occur relatively quickly – within a few minutes or hours. Such sunburn can result in the redness of the skin, ulcers or even burn blisters, which in severe cases may result in permanent scarring.
Types of photosensitivity
What causes such increased sensitivity to the sun? The answer is – medicine or some natural products particularly rich in certain vitamins, as well as skincare products and some essential oils. Using or consuming one (or few) of the 100+ different substances, orally or topically, may facilitate sunburn.
Phototoxicity and photoallergy
There are 2 types of chemical photosensitivity: phototoxicity and photoallergy. In the event of photosensitivity, sunburn rash most frequently appears on skin that has been exposed to the sun – face, neck, décolleté, arms or legs. However, this does not exclude cases where the rash may also appear on skin that was covered from the sun.
Phototoxicity includes symptoms such as pain, redness of the skin, sometimes discolouration of the skin that was exposed to the sun (brown or blue-grey spots). Unlike regular sunburn, the following symptoms appear on the skin after taking certain drugs:
- tetracycline group antibiotics
- diuretics – urinary medicine
- non-steroidal anti-inflammatory drugs such as ibuprofen, paracetamol, etc.
- retinoids – substances or drugs that accelerate the division and recovery of skin cells, used in treating acne
- anti-hypertensive drugs – used to treat high blood pressure
- psychotropic drugs, such as antidepressants
- cholesterol-lowering drugs
- or after application of chemical substances on the skin – perfume, cologne, products containing tar, essential oils. Also, some plants (lime, lemon, celery, parsley, hogweed, St. John's wort) make the skin more sensitive to the effects of sunlight because they contain photo-coumarins.
All phototoxic reactions appear only on the areas of the skin that have been exposed to sunlight. Normally, sunburns appear within a few hours after the exposure to the sun.
Photoallergy is a type-IV delayed allergic reaction, including symptoms such as redness or flaking of the skin, swelling, itching and sometimes blistering. This sunburn reaction is caused by shaving lotions, sunscreens and other skincare products. Photoallergic reactions may also occur on skin that has not been exposed to direct sunlight. The rash occurs later than in cases of phototoxicity – up to 24 to 72 hours after the exposure to the sun.
This reaction is slightly more complex since it also involves the activation of the immune system. The body mistakenly begins to think that the sun, combined with the drugs, poses a threat, so it begins to protect itself against it, causing a rash similar to a sunburn.
It should be noted that sometimes these reactions tend to develop from one into the other, or even co-exist simultaneously. In any case, the best preventive measure and treatment is avoiding direct sunlight. I will outline more preventive measures at the end of the article.
How does the reaction within the body take place exactly?
Redness of the skin caused by sunburn occurs due to enlargement of blood vessels. When this happens, biologically active substances that make up inflammatory processes – swelling, burning or smarting sensation, even pain – are released from the blood vessels. The specific area of the skin appears warmer compared to the rest. As a result of the process, one layer of the skin separates from the other, resulting in blisters, such as rash, ulcers or burn blisters.
How to tell if a rash is caused by drugs or cosmetic products?
If you've been exposed to the sun recently and redness of the skin has appeared, gradually causing a smarting sensation, you may be developing a case of phototoxicity or photoallergy. If you've been exposed to the sun for an extended period and the redness of the skin is limited to the areas that were exposed to sunlight, it may be a simple sunburn. However, if the reddened areas are small and a burning sensation is felt, you may be suffering from photosensitivity.
It is said that a simple way to determine whether the rash is caused by photoallergy or phototoxicity is to push down hard on the reddened area with your finger – if the area becomes pale, you have photoallergy and the reaction is most likely caused by some topically applied substance.
However, if the area of the skin does not become pale, it is phototoxicity and it may have been caused by medicine or something that you have eaten. I should point out that, being a medical professional, I do not recommend such “testing” since it is not 100% reliable or accurate. It is always best to turn to an experienced dermatologist.
What to do in the event of a sunburn caused by photosensitivity?
- Avoid further exposure to the sun.
- Discontinue the use of the drugs that have caused photosensitivity (if possible). Refrain from exposure to the sun for a few days after the discontinued use of the medication.
- Reconsider your skincare products. Avoid using products that are heavy in chemicals or of poor quality. Note that essential oils that are not distilled may cause sunburn when exposed to sunlight.
- Use sunscreen with SPF 50 at least, applying it before exposure to the sun. It is recommended to buy hypoallergenic products from a pharmacy in order to avoid the vicious circle of developing photosensitivity caused by chemicals in the sunscreen.
- Wear light-coloured, long-sleeved clothing, preferably made of cotton. Avoid wearing clothing from wool or synthetic material. Wear a hat, which protects the face from direct sunlight.
Dermatology resident Dace Buile
Lugović-Mihić, L. (2017). Drug-Induced Photosensitivity – a Continuing Diagnostic Challenge. ACTA CLINICA CROATICA, 277–283. doi:10.20471/acc.2017.56.02.11
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