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Food Allergy (cont.)

Food Allergy Symptoms

A person with a food allergy can have symptoms beginning as soon as 2 minutes after eating the food, but reactions may take 1 to 2 hours to appear. Occasionally, symptoms abate quickly, only to recur in 3 to 4 hours.

  • The most common symptoms include the following:
    • Itching of the skin followed by hives, a rash of raised, reddish bumps or wheals
    • Swelling of the lips and mouth
    • Belly cramps
    • Nausea
    • Vomiting
    • Diarrhea
  • Other symptoms may include the following:
    • Itching and watering in the eyes
    • Runny or stuffy nose
  • Symptoms of a more severe reaction could include the following:
    • Shortness of breath or difficulty breathing
    • Tightness in the chest
    • Feeling of tightness or choking in the throat
    • Rapid or irregular heart beat
    • Feeling dizzy or light-headed
    • Losing consciousness
  • A severe allergic reaction can be life threatening. This severe reaction is referred to as anaphylaxis, or anaphylactic shock.
    • The dizziness, lightheadedness, and loss of consciousness are due to dangerously low blood pressure, called "shock."
    • An anaphylactic reaction can begin suddenly, or it may develop gradually with itchiness and swelling of the skin and throat and then progress to a severe reaction over a few hours.
    • Most people get such a reaction immediately after eating the food, but in a few unusual cases the reaction occurs only after exercising following the ingestion of the food.
    • Severe reactions are most often seen with allergies to nuts, fish, and shellfish, although allergy to any food can cause anaphylaxis.
    • People with asthma, childhood allergies, eczema, or prior severe food allergies are especially at risk for having an anaphylactic reaction.
  • MSG reaction can be mistaken for an allergic reaction.
    • Symptoms of MSG reaction include the following:
      • Burning sensation at the back of the neck and radiating down the arms and chest
      • Tingling and numbness in the same areas
      • Headache
      • Nausea
      • Occasionally, difficulty breathing, especially in those with poorly-controlled asthma
    • A few people experience seizures, irregular heartbeats, and anaphylaxis after the use of MSG.
    • Contrary to popular beliefs, MSG has no relation to Alzheimer disease, Huntington chorea, or other chronic illnesses.
Medically Reviewed by a Doctor on 11/20/2017
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Adverse food reactions can be broadly classified into 2 categories.

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