Onions are in the Amaryllidaceae family of plants which also includes shallots, spring onions (scallions) and leeks. Allergy to onion is very rare, but it can cause allergic contact dermatitis and urticaria.

An allergy to onions after ingestion is more commonly linked to Non-IgE mediated allergy than a true IgE allergy. It is important if you think you are allergic to complete a food diary to ensure you are not eliminating large groups of food unnecessarily. There are tips on how to make a Food Diary here.

One of the allergens identified in onion are lipid transfer proteins which are panallergens with the potential to cause allergy over large groups of seemingly unrelated foods.

The other identified allergen is a profilin protein. Again this is a panallergen.

If you have allergic symptoms to multiple foods you may be suffering LTP Syndrome.

Allergy to onion can be linked to Celery-Mugwort-Spice Syndrome this is when people are affected by profilin proteins in multiple foods.

An allergy to onion is most often associated with contact dermatitis and urticaria (hives and wheals on the skin), this is due to diallyl disulphide.

Onion is in the Amaryllidaceae plant family, other plants in this family are chives, leeks and garlic. If your allergy is severe these plants may also cause allergic reactions.

Common foods involved in LTP allergy include kiwi, strawberries, sunflower seeds, walnut, apple, mulberry, banana, pea, apricot, cherry, plum, almond, peach pomegranate, raspberry, tomato, grape, celery, peanut, asparagus, cabbage, broccoli, chestnut, lemon, tangerine, orange, hazelnut, lettuce, lentils, lupin, green bean, pear, mustard, wheat and maize.

Profilin proteins are also found in celery, peanut, soyabeans, walnut, lupin, almonds, mustard, hazelnut, kiwi, pineapple, chilli, melon, orange, strawberry, lychee, apple, banana, aubergine (eggplant), peach, pear, tomato, dates, cherry, carrot, barley and wheat.

Let me know if you found any of these interesting or useful. If you spot an article or research that you think is interesting you can message me or tag me on Facebook or Twitter - links at the bottom of the page.