Substances that cause an allergic reaction are called allergens and can lead to many health issues. Besides dust and pollen, other common allergens include animal dander, foods, including nuts and shellfish, and certain medicines, such as penicillin.
There are many ways you can test for allergies. Here I list a few of the most common ways.
Your skin is exposed to suspected allergy-causing substances (allergens) and is then observed for signs of an allergic reaction. Skin tests are most reliable for diagnosing allergies to airborne substances, such as pollen, pet dander, and dust mites, but may also help diagnose food allergies.
According to MedlinePlus skin tests aren’t always accurate. They sometimes indicate an allergy when there isn’t one (false positive), or skin testing may not trigger a reaction when someone is exposed to something that they are allergic to (false negative). One may react differently to the same test performed on different occasions. Or one may react positively to a substance during a test but not react to it in everyday life.
These are used to test immunoglobulin IgE. The total IgE test measures the overall number of IgE antibodies in your blood. Specific IgE tests measure the level of IgE antibodies in response to individual allergens
Allergy Pulse Test
When one is exposed to an allergen (something that one is allergic to), there is an increase in heart rate. First find the baseline pulse, done by taking the pulse (heart rate), at rest, for one minute. Then eat a food that is a possible allergen. Next, check the pulse in 15, 30 and 60 minutes. If the heart rate increases more than 10 beats per minute over the base pulse, it indicates that there may be allergy to that particular food
An elimination diet is really the best way to determine what foods are causing a reaction. Also one is testing the actual food that they are consuming which could be cross-contaminated with other foods. For instance, one may eat a food that they are not allergic to but is processed in the same facility as nuts to which they are allergic.