Questions to Dr. Andreas Kruppa, specialist in dermatology in Cologne biszet: Dr. Kruppa, we have designed exclusive furniture for the bathroom that is characterized by its elegance and which has a unique feature that has never previously existed in this form. It allows the simultaneous storage and refrigeration of cosmetics. What do you think of this idea? Dr. A. Kruppa: I think it’s a very good idea. Many women already keep their cosmetics in the kitchen refrigerator. It’s much more practical not to have to keep running back and forth between bathroom and kitchen. biszet: Many cosmetics and skin care products bear the notice “please store in a cool place”. Why is it so important to keep them cool? Dr. A. Kruppa: Once opened, bacteria, germs and yeast spores often manage to penetrate the product jars. These particles are airborne but succeed in getting into the jars through the use of fingers to remove cream. This colonization by germs can take place at high temperatures much more rapidly than at cool ones. It’s similar to what happens when one forgets to put an open bottle of milk in the fridge – the germs are able to develop much more quickly and the milk turns sour. biszet: Do you also routinely use chilled creams in your surgery? Dr. A. Kruppa: Certainly. After laser therapy, for example, chilled creams containing plant extracts are applied to the skin because they are soothing and the chilling helps reduce the swelling.. biszet: What is the optimum temperature range for the storage of cosmetics? Dr. A. Kruppa: Quite simply, cool temperatures make it harder for bacteria to feel at home than in warm temperatures. Bacteria prefer the warm, humid climate that is primarily caused by sunlight. They also like it when condensation occurs in the tubs. And at 20 °C germs multiply much more rapidly than at 10 °C. But the temperature shouldn’t be too cold, otherwise the contents start to crystallize. That is why it is better to put cosmetics into your cabin luggage when flying, because in the aircraft’s hold the temperatures often go down to minus 40 °C. I therefore generally recommend storing cosmetics at around 10 °C and those containing collagen at around 12 °C. Vitamin-based products should preferably be stored at 5 to 8 °C. biszet: What effect does refrigeration have on the efficacy of the cosmetics? Dr. A. Kruppa: Using chilled creams and lotions is much more pleasant than using warm ones. Subjectively, the chilling causes the skin to tauten thanks to the contraction of the blood vessels, and this in turn improves circulation. The vessels subsequently expand again and the active ingredients can be absorbed much more rapidly and effectively. biszet: In their pamphlets, some cosmetic manufacturers even recommend “avoid warming the creams in one’s hands, in order to retain maximum effect". Which ingredients react so sensitively? Dr. A. Kruppa: All sorts of ingredients can be affected. Many anti-ageing creams contain vitamin C, for example. This oxidizes very quickly and so loses its efficacy. As with many other chemical reactions, this process is speeded up through warmth. biszet: Many men and women are already using skin care products that contain no preservatives. What are the advantages and disadvantages of such products? Dr. A. Kruppa: Many patients develop a contact allergy against preservatives such as parabene. Eczema occurs and this can be very discomforting for the person affected. In addition, creams that do not contain preservatives turn rancid much more quickly and are colonized by germs much more easily. biszet: What can a rancid cream do to the skin? Dr. A. Kruppa: Apart from the loss of efficacy, all sorts of different skin irritations can result, such as redness, a burning feeling, and flaking. Rancid creams can be identified by the change in their smell – they smell putrid. Their consistency can also change – the contents frequently separate into thin and thick parts. All signs that undesirable chemical reactions have taken place that can cause quite a different reaction on the skin to the one originally desired. biszet: Dr. Kruppa, many thanks for the very informative interview. Dr. A. Kruppa: My pleasure. • back