Sir, given its widespread occurrence in our diet, it is virtually impossible to avoid daily exposure to fluoride. It therefore seems highly improbable that H. Keanie's patient is allergic to fluoride (Fluoride allergy BDJ 2007; 202: 507).

The possibility of allergy to fluoride has been investigated by eminent experts in the field of allergy both in the UK and in the US. Reviews by Challacombe,1 NHMRC2 and NRC3 all concluded that the studies undertaken do not support claims that fluoride is allergenic. They considered the weight of evidence to show that fluoride is unlikely to produce hypersensitivity or other immunological effects.

According to Challacombe1 there have been no confirmed cases of allergy to fluoride or of positive skin testing in humans or in animals and there is no increased reporting of allergies of any type with increasing fluoride use. Fluoride is also found in many foods and drinks, and there are no reports of reactions of an allergic nature to fluoride in such commonly encountered substances – for example tea and tinned fish.

Finally, the Medical Research Council4 considered the weight of evidence to show that fluoride is unlikely to produce hypersensitivity or other immunological effects.