Allergy :

Unfortunately celery can cause a number of skin reactions. If celery comes into contact with the skin, it can make the skin very sensitive to sunlight ( photosensitivity ); even a small amount of subsequent sun exposure can cause blistering. It seems to particularly affect pickers, canners and food store workers. Celery is prone to infection with Sclerotinia sclerotiorum (pink rot) which significantly increases the available amount of photo-sensitising chemicals. Occasionally, ingestion of these chemicals in celery soup can cause generalised sun sensitivity; several people have developed severe sunburn after eating celery soup and then going out in the sun or to a tanning salon. Celery can also cause rashes unrelated to sun exposure. There have been reports of allergic contact dermatitis ( eczema ), acute urticaria (hives), angio-edema (skin swelling) and anaphylaxis (severe allergy resulting in collapse) due to celery, both from direct contact with the skin and after ingestion. Fortunately these are rare.

Celery oil and celery root are also known causes of acute food-induced anaphylaxis.