Allergic and toxic reactions caused by cream bases in dermatological patients.

Synopsis Irritant and allergic reactions from cream bases observed in eczema patients are reviewed. The frequency of allergic reactions to the ingredients of vehicles in eczema patients is an indication of allergic potential for normal skin. Against this background, hypoallergenic fragrances are still very difficult to produce and a proper mixture for epicutaneous testing is lacking. Among preservatives, parabens are obviously safer and less allergenic than chlorocresol and sorbic acid. Propylene glycol (PG) is very popular for its many beneficial properties. However, it is also an irritant and a sensitiser. The exact number of allergic delayed type reactions is difficult to establish because primary irritant epicutaneous test reactions often closely resemble allergic reactions. By doing epicutaneous tests with serial dilutions of PG and by making peroral challenge tests, the number of eczema patients allergic to PG has been estimated to be as high as 1%. Glycerol is much less active in producing toxic and allergic skin reactions. Common non-ionic emulsifiers and higher fatty alcohols cause allergic contact dermatitis occasionally. The allergenic properties of these substances have not yet been examined experimentally. It seems, however, that there are only small differences between the various emulsifying agents.