For a minor allergic reaction, over-the-counter or prescribed antihistamines may help reduce symptoms. These drugs can be taken after exposure to an allergy-causing food to help relieve itching or hives. However, antihistamines can't treat a severe allergic reaction.
For a severe allergic reaction, you may need an emergency injection of epinephrine and a trip to the emergency room. Many people with allergies carry an epinephrine auto injector (Adrenaclick, EpiPen). This device is a combined syringe and concealed needle that injects a single dose of medication when pressed against your thigh.