Beware of phototoxic substances!

Did you know that certain substances can increase the risk of sunburn? Many people have experienced sunburn even though they applied UV sunscreen and stayed in the sun as long as usual. These burns may have been caused by photosensitising substances that make the skin more sensitive to sunlight and artificial UV radiation.

 

Photosensitising versus photoallergic substances

Sun reactions to photosensitisers can vary. Very often there is erythema, burning and blistering immediately after sun exposure. Later, there may be a pigmentation change, i.e. discolouration of the skin. These are typical reactions caused by phototoxic substances that belong to the photosensitising group. Other symptoms can be photosensitisation with erythema and hyperpigmentation, or photosensitisation occurring with a pseudoallergic reaction (such as urticaria or rash). All these symptoms are the result of a disturbance of the body’s immune system brought about by a photoallergic reaction. The mechanism of such changes is very similar to that of a typical allergic reaction, which is why the substances in the photosensitising family that cause such changes are called photoallergic substances.

Phototoxic substances cause symptoms immediately after application and only at the site of application of the phototoxic preparation. Photoallergic substances, on the other hand, cause a delayed reaction that may only develop after some time, making it more difficult to diagnose. Interestingly, photoallergic reactions also occur on skin that has not been in contact with the preparation.

It is important to remember that photosensitising substances are not harmful to our skin. Many of them have positive effects on our body. Their negative effect manifests itself in combination with sun exposure.

Note that there are a number of photosensitisers.

There are many possibilities for contact with a photosensitising substance. The first correct association is usually cosmetics. However, very often it can also be food products, medicines or herbs. Photosensitising reactions also occur when exposed to chemical or natural substances.

 

Chemical and food photosensitisers

The most common photosensitizers include:

Regularly consumed during the summer, sweeteners, which are found in light products.

Many herbs and plant extracts. The negative effects of st John’s wort in combination with UV radiation are well known. However, there are many more photosensitising plants. Most often these are herbal compositions of unknown composition added to dietary supplements, among others. Dermatologists very often diagnose photosensitisation in patients taking herbal mixtures of unknown origin and composition. The most common photosensitising plants are angelica, dill, parsley, parsnip, giant hogweed, sumac, celery, wild carrot, and even lime or lemon.

Remember that some photosensitising plants are known spices. The diallyl disulphide contained in garlic is one of the more potent photosensitisers.

quinones, which are natural chemicals found in many plants. There are a number of diverse substances belonging to the quinone group, but not all are sometimes photosensitising. Some quinones contained in wort, medicines or herbal supplements can cause solar hypersensitivity.

Chemical and natural dyes such as rose bengal or eosin, often used in the food and textile industry, can cause skin reactions.

Psoralens, which are chemicals found in lovage and selera, among others.

 

Photo-sensitising cosmetics

Cosmetics are among the second most common causes of photosensitisation of the skin. Many cosmetic preparations contain the above-mentioned ingredients, such as plant extracts, essential oils, dyes or retinodes.

Retinodes. These acidic vitamin A derivatives are some of the most commonly photosensitising ingredients in cosmetics. Many of us cannot imagine life without retinodials because of their positive effects on the skin. However, it is good to know that retinodials should be discontinued during periods of high sun exposure or before applying a chemical peel

Essential oils can cause photo-irritation of the skin. It is very common in the literature to write about bergamot oil as a major photosensitiser. However, other oils e.g. cedar, lavender, vanilla or sandalwood – can also cause such a reaction.

Someperfumes may also be photosensitising. Among other things, they are derived from plants that may contain substances belonging to the photosensitising group.

Some<> perfumes may also be photosensitive.

 

Photosensitisers

Two groups of products that induce skin photoreactions deserve special attention: hormonal drugs and cosmetics.

Hormonal drugs used during menopause and as contraception are one of the main causes of skin hyperpigmentation. Often we are not able to replace photosensitising drugs with their counterparts, so we have to protect our skin in other ways by using clothing and photoprotective filters.

Some cholesterol-lowering drugs. The statins present in the drugs statins, which many of us save our lives by preventing heart attacks and strokes, can cause photosensitising reactions as a side effect.

Some of the drugs that are used to lower cholesterol, such as the cholesterol-lowering drugs, can also cause photosensitising reactions.

Some medicines containing antibiotics in their composition, such as acne ointments. Also, antibiotics themselves are sometimes photosensitising. A warning of this type is usually included on the leaflet of the preparation in question.

Other medications. It is impossible to list all the drugs that can be photosensitising. The most common groups include antiarrhythmic drugs, anticancer drugs, antidiabetic drugs, diuretics and non-steroidal anti-inflammatory drugs. Usually drugs in the photosensitising group warn in the leaflet about such effects.

 

When going on holiday and planning to be out in the sun for long periods of time, let’s not change the skincare habits we use every day at home. Any new cream that we take with us could be the cause of skin photosensitisation.