Hay fever, also known as pollen allergy, is an allergic reaction of the body to certain tree, grass or herb pollens. It is one of the most common forms of allergy and occurs seasonally when the plants in question release pollen. Sufferers are usually affected by hay fever during the spring and summer months. However, pollens may be released at other times of the year depending on the geographical location and the type of pollen.

The symptoms of hay fever can vary from person to person, but they often include:
a congested nose, sneezing, an itchy throat, itchy eyes, coughing and exhaustion.

A cross allergy means that a person with hay fever has an allergic reaction to certain foods or substances that contain similar proteins to the original allergen (pollen). The similarity of the proteins can lead to an allergic reaction also being triggered when these foods are consumed, even if the person does not come into direct contact with the pollen in question. Symptoms such as tingling on the palate or a burning and itching sensation in the mouth area may occur.

More information about cross allergies and which foods are mainly affected is described on the following page: Allergy Centre Switzerland 

A cross-allergy does not necessarily mean that certain foods have to be avoided. For example, an apple can be eaten in a processed form, for example as apple pie, because the protein structure is changed by heating.