Products
Salicylic acid is available in combination with other active ingredients in a number of externally applied medicines. It is also contained in numerous extemporaneous preparations that must be prepared for customers in a pharmacy. Corresponding manufacturing instructions can be found, for example, in the DMS (e.g., salicylaseline).
Structure and properties
Salicylic acid or -hydroxybenzoic acid (C7H6O3, Mr = 138.1) exists as a white crystalline powder or in the form of white to colorless crystal needles that are sparingly soluble in cold water and slightly soluble in ethanol 96%. It is more soluble in hot water. Salicylic acid has an acrid sweet and sour taste. It occurs naturally in the form of derivatives in many plants, including silver willow L. It belongs to the phenols and carboxylic acids.
Effects
Salicylic acid (ATC D01AE12, ATC S01BC08) has antimicrobial (fungal and bacterial), keratolytic, analgesic, and anti-inflammatory properties.
Indications for use
Salicylic acid is used externally as a skin and cornea dissolving agent against warts, acne, corns, dandruff, ichthyosis, psoriasis, thickening of the foot and hand horny layer and horny eczema, among others. Another field of application is the external treatment of pain and inflammatory conditions, for example, in the form of rheumatic ointments.
Dosage
According to the product information. Use depends on the product. Salicylic acid is no longer administered internally because of its adverse effects. The derivative and prodrug acetylsalicylic acid (aspirin, generic) is available for this purpose.
Contraindications
Salicylic acid is contraindicated in hypersensitivity and during pregnancy and should be applied only to small areas because it is absorbed through the skin into the bloodstream. Do not apply to the area around the eyes or mucous membranes or to open wounds, and do not take orally as an analgesic. Salicylic acid should not be used as a precaution in children and adolescents with viral infections because of the risk of Reye’s syndrome. Refer to the appropriate drug labeling and package inserts for complete precautions.
Adverse Effects
Salicylic acid is irritant and may cause irritation of the skin and mucous membranes, such as redness and a burning sensation. Hypersensitivity reactions are possible (salicylate allergy). Salicylate poisoning has been reported with large-area application on the skin. Ingestion may cause gastrointestinal symptoms including dyspepsia, nausea, vomiting, diarrhea, gastrointestinal bleeding, and gastrointestinal ulceration. Overdose manifests as gastrointestinal symptoms, hyperglycemia or hypoglycemia, skin rashes, dizziness, ringing in the ears, visual and hearing disturbances, tremors, confusional states, hyperthermia, sweating, hyperventilation, disturbances of acid-base balance and electrolytes, exsiccosis, coma, respiratory failure.
As a preservative for tomatoes.
Salicylic acid is an obsolete preservative that was used, among other things, for cooked and peeled tomatoes (incidentally, acetylsalicylic acid (aspirin), the acetylated derivative). Its use is controversial and banned in many countries. Salicylic acid can irritate mucous membranes due to its keratolytic properties and lead to numerous adverse effects, especially in higher doses. When heated, the toxic phenol is formed. We cannot conclusively assess how high the health risk actually is in the recipes used. Of course, it also depends on the amount of acid added (usually 1 g / kg) and the amount of tomatoes consumed. From our point of view, against this background, salicylic acid should no longer be used as a preservative for food, even in private. Alternatively, tomatoes can be deep-frozen without preservation, for example, and thus have a shelf life of 6 to 12 months. Further recipes can be found in tomato recipe books.
