Some skincare products are applied over large areas of the skin as body lotions and absorb significant amounts of the minor components present in oils and extracts. Intolerances therefore quickly manifest themselves in the form of visible irritation or allergic reactions.
A typical example of such a minor component is salicylic acid, which enters products via plant-based ingredients – particularly extracts – or is often deliberately added as a synthetic substance.
Natural Pharmacy
In folk medicine, salicylic acid was one of the first compounds known from the natural medicine cabinet. As acetylsalicylic acid (ASA), it is now used in large quantities worldwide as an over-the-counter medicine.
Intolerance
Apart from possible allergic reactions, such as those that many natural substances can trigger on sensitive skin, the predominant issue with salicylic acid is intolerance, which is attributable to its phenolic structure and acidic nature and is not comparable to the effects of ASA.1 This intolerance manifests itself on the skin, for example, as itching and/or redness.
Physiologically, salicylic acid poses no problem in the quantities found in food and cosmetics. It is excreted by the kidneys within a few hours via conjugation, which may be preceded by oxidation (in the liver).
Preservative and active ingredient
Salicylic acid, its salts (salicylates) and esters such as benzyl salicylate are used specifically in cosmetics for various purposes:
- Preservative – due to its phenolic and acidic structure
- Anti-inflammatory effect, e.g. for acne – due to its antimicrobial action
- Exfoliation – due to its keratolytic activity
- Fragrance – in the case of benzyl salicylate
Natural constituent
The levels found in food vary from almost 0% to around 0.02% in fresh fruit and vegetables. Freeze-dried foods, including anhydrous spices, may contain up to around 0.2% salicylic acid. Naturally, these levels are not declared in either food or cosmetics (e.g. when plant extracts are used).
This sometimes results in a business model whereby products are marketed as ‘salicylic acid-free’. On closer inspection, however, one finds that some of these products, by virtue of their composition, cannot possibly contain any salicylic acid at all.
Cosmetics Regulation
The European Cosmetics Regulation limits the concentration of salicylic acid – calculated as free acid – to a maximum of 2 per cent when used as an active ingredient. However, particularly because of the potential for widespread use over the whole body, only 0.5 per cent is permitted in body lotions. The same applies to products such as lipsticks, some of whose ingredients are ingested or, as well as to deodorants and products for use around the eyes.2 An exception, with a maximum of 3 per cent, is made for hair treatment products that are rinsed out.
Where salicylic acid is used solely as a preservative, a maximum concentration of 0.5% is permitted.3
Its use on children under 3 years of age is strictly prohibited. The same applies to mouthwashes and dental care products.
Higher concentrations of salicylic acid are found in medical devices and topical medicinal products that are not subject to the Cosmetics Regulation, where they are used for the keratolytic removal of warts or similar conditions.
dermaviduals® preparations
Each contains 0.5% salicylic acid for spot treatment of blemished skin and to help prevent acne. The products can be used without restriction during pregnancy.
References
- B. Rosenkranz et al., Effects of salicylic and acetylsalicylic acid alone and in combination on platelet aggregation and prostanoid synthesis in man, Br. J. clin. Pharm. (1986), 21, 309-317
- Annex III of the Cosmetics Regulation (KVO): List of substances which may be contained in cosmetic products only subject to the specified restrictions
- Annex V of the Cosmetics Regulation (KVO): List of preservatives authorised for use in cosmetic products
Dr Hans Lautenschläger
| 
Menu skin topics
>>
question & answer
