Buckwheat, despite its name, is not botanically related to wheat. Thus individuals who are allergic to wheat, barley, rye and similar cereals can usually eat buckwheat. Similarly, buckwheat flour can be safely used by individuals with coeliac disease (provided that it has been milled separately from wheat, rye, barley or oats).

Allergy to buckwheat is one of the more common food allergies in Korea and Japan. As with most food allergens, the most common symptoms involve the skin, especially urticaria (hives). Severe symptoms such as anaphylaxis have been reported and also exercise induced anaphylaxis i.e. anaphylaxis which only occurs when consumption is followed within a few hours by exercise such as running.

Buckwheat is not named in the European or American labelling regulations but labelling of buckwheat is mandatory in Japan, reflecting the much higher prevalence of this allergy in Asia.