How can i treat an allergic reaction?

Benadryl (diphenhydramine): Immediately stop eating the food you think is causing the problem. Take liquid or dissolving Diphenhydramine (benadryl). If your reaction is worse: cough, shortness of breath, wheezing, chest tightness, difficulty breathing, hives all over your body, swelling of lips and tongue, etc., then you need to use your Epinephrine autoinjector (epipen, twinject) and go to the nearest emergency room.

Allergy treatment: The usual sequence involves avoidance, then medications to treat symptoms, and thirdly consideration of possible immune alteration with allergen immunotherapy or other morality (ie omalizumab). As with any disease these would be patient, symptom and cause dependant.

Depends on severity: Severe allergic reactions (like anaphylaxis) that involve chest/throat symptoms are treated with Epinephrine for immediate relief and oral steroids. Milder allergic reactions that affect skin, nose, eyes are usually treated with antihistamines. The real goal is to identify the trigger, so it can be avoided. An allergist is uniquely trained to diagnose and appropriately treat allergic reactions.