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Symptoms of an Allergic Reaction

Symptoms of an allergic reaction vary depending on the body part affected and the severity of the reaction. Some reactions affect many areas, while others affect just one area. Reactions to the same allergen vary by individual.

Symptoms of an allergic reaction include any, some, or many of the following:

Recommended Related to Allergies

Smog: Not an Allergen, but an Irritant

For people with allergies and asthma, sometimes the very air they breathe can be bad for their health. That’s because a variety of pollutants in our air -- collectively called smog -- can aggravate asthma and allergy symptoms, leaving people with these conditions struggling to breathe.

Read the Smog: Not an Allergen, but an Irritant article > >

  • Skin -- Redness, itching, swelling, blistering, weeping, crusting, rash, eruptions, or hives (itchy bumps or welts)
  • Lungs -- Wheezing, tightness, cough, or shortness of breath
  • Head -- Swelling of the face, eyelids, lips, tongue, or throat; headache
  • Nose -- Stuffy nose, runny nose (clear, thin discharge), sneezing
  • Eyes -- Red (bloodshot), itchy, swollen, or watery
  • Stomach -- Pain, nausea, vomiting, diarrhea, or bloody diarrhea

Anaphylaxis is serious, potentially life-threatening allergic reaction which is rapid, or sudden, and potentially life-threatening.

One sign of anaphylaxis is shock. Shock has a very specific meaning in medicine: the organs of the body are not getting enough blood because of dangerously low blood pressure. This drop in blood pressure happens when the large blood vessels suddenly expand. If the drop in blood pressure is sudden and drastic, it can lead to unconsciousness, even cardiac arrest and death.  

The person in shock may be pale or red, sweaty or dry, confused, anxious, or unconscious.

Breathing may be difficult or noisy, or the person may be unable to breathe.

 

WebMD Medical Reference

Reviewed by Luqman Seidu, MD on May 18, 2014

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