Everything you want to know about sun protection

Sunbathing is associated with warm, especially summer days, sunshine, holidays, holidays, staying by the water, whether sweet or salty. It is a sought-after and popular activity for many of us. In addition to golden skin, it can also have negative effects. To prevent or at least alleviate them, read the following article.

Sunlight consists of UVB (5%), which is responsible for deoxyrybonucleic acid damage. Unrepaired damage is the essence of carcinogenesis, ie the risk for skin cancer, such as melanoma, and UVA (95%), which acts indirectly, accelerating the formation of free radicals, contributes to pigmentation (darkening), photoaging - skin aging, also skin cancers, especially melanoma, causes photosensitivity and photoallergic reactions.

Photosensitivity reaction - the action of UVA, especially on fair skin type, causes a skin reaction that is similar to a urticaria reaction with redness, blistering, and burning. The reaction occurs, for example, on substances contained in St. John's wort, tars, corticosteroids, salicylic acid, in various intensities on essential oils, diuretics, non-steroidal anti-inflammatory drugs (eg ibuprofen, diclofenac, etc.), tetracyclines, amiodarone, antihistamines and many other substances. whether the preparations are applied topically to the skin or mucosa, or systemically (in the form of tablets, transdermal patches, suppositories, etc., dosage forms intended for the systemic effect of the drug). Bearings treated with products containing such substances must not be exposed to the effects of UV radiation (sun, solarium) during the treatment and usually for another 14 days after its completion.

Another possible manifestation is a photoallergic reaction, which is the result of a cellular immune response (late reaction, type IV allergic reaction) and is mediated by T-lymphocytes. A photoallergic reaction occurs after sensitization, by which the drug binds to a protein and changes into a photoantigen that elicits said immune response. A typical manifestation is usually papulovesicular seeding (papules = pimples and vesicles = papules with small blisters) accompanied by itching. In chronic conditions, flaking and lichenification persists (ie roughening of the skin with the formation of flat polygonal papules; Latin "lichen" means lichen and lichen). Any substance that causes a phototoxic reaction can cause a photoallergic reaction.

The onset of hypersensitivity is affected by a number of factors, such as time and method of application, repeated use, drug concentration in the skin, properties of constitutive excipients, dose of absorbed radiation, etc. An airtight dressing increases absorption and thus the risk of contact hypersensitivity, as well as a broken skin barrier.

Skin reaction to the sun's rays:

- primary (immediate) erythema, ie reddening of the skin caused immediately by irradiation with infrared rays, which causes vasodilation (dilation of blood vessels), while the primary erythema disappears in the shadows;

- late (secondary) erythema - appears within 2 to 8 hours after the start of UV irradiation and shows signs of inflammation, ie redness, pain, swelling, is replaced by pigmentation and peeling of the skin;

- early pigmentation, ie immediate darkening of the pigment, persists for several days;

- late pigmentation, UVB rays cause new melanin formation in the skin.

Changes in the skin that are associated with chronic UV radiation

- skin aging (photoaging), elastosis, when the elastic fibers are transformed into an amorphous mass, subcutaneous capillary loops are formed, blood vessels dilate, the skin thickens due to increased cell division;

- photocarcinogenesis.

PHOTOPROTECTION - protection against the negative effects of UV rays

Natural photoprotection

- formation of an integral corner layer of the skin and melanin pigmentation;

- protection can also be attributed to beta-carotene and antioxidants.

Artificial photoprotection

Sun protection factor (SPF) , defined as the ratio of the minimum erythema dose in skin protected by a sunscreen to the minimum erythema dose in unprotected skin. With a higher SPF value, skin protection is better; this factor concerns only the protection of the skin against erythema, it does not include other effects of UV radiation, such as immunosuppression, photoaging, cancer, malignant melanoma.

Substances that either absorb or reflect UV radiation are used as so-called sunscreens.
UV absorbers (so-called chemical filters) include chemical substances that absorb radiation responsible for the formation of late reddening of the skin.

If these substances are not stable, secondary photoreactions occur and photosensitization may occur. It follows that it is necessary to buy not only quality products with a high SPF factor, but not to leave them, for example, all day in full sun, hidden in the sand, so that they do not overturn, etc.

Full effectiveness develops up to 30 minutes after application. It is therefore necessary to use the product in advance if you plan to tan.

UV-reflecting substances (so-called physical filters) include inorganic substances, most often titanium dioxide, zirconia and zinc oxide. These substances are biologically inert, do not irritate, do not cause photosensitization, do not have a phototoxic effect.

The full effect is immediate. The disadvantage compared to chemical filters is, from an aesthetic point of view, a whiter skin color (which does not prevent tanning).

Solar filters are manufactured in various application forms. These include milks (or emulsions which, if they are of the water-in-oil type, hydrate the skin and prevent it from drying out), hydrogels, pigmentation filters - to cover depigmented areas of the skin, such as vitiligo, sprays, lip sticks. In addition to products that are supposed to prevent the negative effects of UV radiation, SPF also includes a number of cosmetics - lipsticks, skin and body creams.

Water resistance is also an important factor when choosing a sunscreen. Water resistant means that the product should remain on the skin in the same protective quality when soaked in water for 40 minutes, water proof (sometimes also vwr - very water resistant) means that the product will remain in the same protective quality for up to 60 minutes, being fresh, salted and chlorinated water.

The products must be applied repeatedly, as their effect is affected by bathing, sweating, wiping the skin.

COLIPA - The European Cosmetics Toiletry And Perfumery Association, is an independent association of European associations, cosmetics manufacturers and other partner organizations that deals with testing and setting standards for the production of products in the cosmetics and perfumery industries.

According to the COLIPA recommendation, the SPF value of the solar filter must include both protection against UVB and UVA radiation, a product with the UVA logo contains filters against both UVB and UVA radiation, in a ratio of 3: 1, ie a product marked eg SPF 15 provides UVB protection. at least 15 and at least 5 against UVA radiation. The standard does not allow the labeling of products with a factor higher than 50, therefore the designation "50" (extreme) is used .

Rule for selection of protection factor - UVA and UVB

- people with photodermatoses should have a factor of at least SPF 20,
- patients with chronic actinic dermatoses and exogenous photosensitivity should use filters with a high SPF, based exclusively on micronisation of pigments (physical factors) without stabilizers, emulsifiers and odors;
- chemical peeling, laser treatment, vitiligo, surgical procedures - in such places it is always necessary to use a high factor combining physical filters with chemical ones.

remember

No product protects 100% from the negative effects of UV radiation.
No product is enough to use once a day.

You can consult a specialist pharmacy staff about the selection of a suitable product, or write to us at info@nefertitis.cz