answered by Univ. Prof. Dr. Peter Wolf, dermatologist in Graz/Styria.
Is the sunscreen from the previous year still effective
Modern sunscreen preparations are formulated stable. The UV filters contained do not lose their effectiveness when stored and handled properly. As long as a product from the previous year was not exposed to excessively high temperatures for longer periods of time and was not contaminated, its effectiveness is to be expected. The consumer recognizes this by the fact that a product feels good, is not friable (has not broken down into its individual constituents) and smells pleasant. In particular, sunscreen products with DNA repair enzymes can, however, lose their effectiveness by exposure to high temperatures for long periods of time (for example leaving a product in the car, etc.).
How to combine facial care and sunscreen?
The facial care is in principle to vote on the skin type; this means more moisturizing skin emulsions for dry skin types, gels and emulsions for greasy skin types for care in summer. The same applies to sunscreen: gel preparations for greasy skin types, more moisturizing sunscreen emulsions for dry skin types.
How often should you reapply the sunscreen?
Unless it comes to the abrasion of a sunscreen preparation on the skin, for example, by mechanical friction in the sand on the beach, drying after swimming or extreme sweating, usually sunscreens should be reapplied every 2 hours.
Which sunscreen should children use?
Preference is given to sunscreen products whose action is predominantly on physical UV filters, based on pigments such as zinc oxide or titanium dioxide. For toddlers extremely greasy sunscreens should be avoided, especially in the facial area, to prevent a heat accumulation.
Which cream should allergy sufferers use?
Allergy sufferers should pay special attention to the ingredients of sunscreen products and avoid products containing known allergens. This is possible through the exact study of the so called INCI declaration list of a product, on the small-print of the packaging. For proven allergies, the consultation of a skin specialist is recommended. People with very dry skin who are prone to eczema should avoid sunscreen products based on gel and should use moisturizing emulsions or creams instead.