Allergy to molluscs such as snail is less common than allergy to shrimps. Snail allergy is associated with an unusual distribution of symptoms with asthma being very frequently reported. However, mild symptoms such as oral allergy syndrome, urticaria (hives) and severe symptoms such as anaphylactic shock can also occur after consumption.

Allergy to snail is frequently associated with allergy to dust mites and this may account for the high frequency of asthma and rhinitis seen as symptoms. There are also concerns that desensitization therapy with dust mite extracts may cause a more severe reaction to snails. Some individuals with allergy to shrimp (crustacea) may also suffer associated allergy to snail. For others, their allergy to snail is associated with allergy to other shellfish (molluscs) such as abalone and limpet which can include serious or fatal reactions.

Allergic reactions have been reported to several species of snails including the brown garden snail (Helix aspersa), the burgundy snail (Helix Pomatia), and the vinyard snail (Cernuella virgata). Helix terrestre may be a synonym for one of these. Euparipha pisana is probably Euparypha pisana also called Helix pisana and probably most correctly Theba pisana or the white garden snail. Allergic reactions to the sea snail Bolinus brandaris have also been reported.

Image of Helix aspersa by Jeremy Lee reproduced with permission from http://www.uknature.co.uk/GSnail-info.html.