In many people with pollen allergy, nuts, spices, fresh fruit and raw root vegetables can cause local itching around the mouth, lips or throat. This so-called cross-allergy doesn’t usually develop into a severe allergic reaction.
In cross-allergy, the symptoms are triggered by proteins in certain foods that are similar to pollen allergens. The allergen can also be some other protein in the food. Food allergies include milk, wheat and egg allergies that are common in childhood. They either disappear or subside in adulthood. Some food allergies are more permanent, such as fish or seafood allergies. Things are not always straightforward, however, as nut allergy for instance can be a mild cross-allergy or a severe “direct” allergy. The risk of severe reactions can be determined with a blood test that looks at the antibody profile in terms of a few common foods.
The symptoms can be mucosal as in cross-allergies, or itching, hives, sudden nausea, stomach pain and vomiting after eating. Food allergies in adults rarely cause atopic skin symptoms. Particularly in cross-allergies, raw vegetables and root vegetables can cause itching and hives even via skin contact.
Cross-allergies related to pollen allergy can cause more pronounced symptoms during the pollen season. You may have to avoid certain foods during this period. However, it is nowadays recommended that you can eat a varied diet without avoiding foods that cause mild symptoms. This is to maintain tolerance despite the cross-allergy. In the case of severe cross-allergies, avoiding trigger foods may be necessary. If you are sensitised directly by certain proteins in foods and have severe symptoms, you must avoid these foods altogether.
Antihistamine rapidly alleviates mucosal itching and other mild symptoms.
When should you seek treatment?
If you experience a severe, generalised reaction (anaphylaxis) during or after eating, take an antihistamine tablet immediately if available and seek emergency help. After receiving emergency help, you should come in for tests. If the allergen is unknown, prepare detailed information about the foods you’d eaten before the reaction. The cause of the reaction will be investigated, and the doctor will prescribe you first-aid medicines for any future reactions.