Most food allergies start in childhood, but some can develop during adulthood.
No one is sure why this happens, but a person can eat a food for years and then suddenly experience an allergic response. This is not a common occurrence, however, so any sudden allergy should be discussed with your doctor.
You may suspect an allergy if you are experiencing symptoms every time you eat peanuts. But since the experience is new, you may not be sure. Peanut allergies are very common, although developing the allergy as an adult is unusual.
What are common symptoms?
associated with a peanut allergy. A mild allergic reaction would be the development of hives, itchiness, abdominal pain or nausea all happening shortly after eating peanuts. The symptoms will appear early in the exposure. If the symptoms don’t occur until hours later or even the next day, it is probably not a
In severe allergic responses, peanuts may cause swelling in the airways making it more difficult to breathe, and in some instances may cause low blood pressure. When there are severe reactions like this, peanuts must be avoided entirely. In any case, it's best to see an allergist about a test to identify the source of the allergy.
Once a doctor confirms your peanut allergy, you will need to take precautions to ensure that you avoid peanuts. Read all labels for any food you ingest and be cautious of homemade or unpackaged foods where there is no label. Some peanut allergies increase in severity with each exposure, so limiting access to peanuts is important. Avoid exposure to skin through touch (soaps and lotions) and smells (peanut butter aroma). Secondary exposure, in which you are exposed through surfaces or nut proteins on another person’s clothing or skin, should also be reduced. Peanut shells can set off an allergic response in some people.
Source: Mayo Clinic