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First Aid: Allergic Reactions

Limited reaction

A limited (localized) reaction affects only the area of contact. Some reactions may not show up for days. Others can occur almost right away.

Step 1. Stop the source

  • If the person has been stung, calmly move away from the area to prevent more stings. Scrape the stinger away with the edge of a credit card. Or the dull edge of a knife. Don’t use fingers or tweezers to remove a stinger. If pinched, the stinger may empty its venom into the skin.

  • If the reaction is caused by eating a specific food or taking a medicine, the person should not eat or take the substance again.

Step 2. Treat skin irritation

  • Wash insect bites with soap and water.

  • Remove and wash in hot water all clothing that may have plant oils. Or any other substance that has caused a reaction on them. Shower with plenty of soap to wash any plant oils or other allergens off the skin.

  • Ask your healthcare provider how to control itchy or irritated skin.

Severe reaction

Anaphylaxis is a severe life-threatening allergic reaction. This needs immediate medical attention. In extreme cases, the airways from mouth to lungs may swell and cause difficulty breathing. The reaction may happen right away or over several hours. Give epinephrine if it's available and call 911 right away for medical help. Call even if the medicine seems to be helping.

Step 1. Calm the person

  • Help the person lie down with their legs raised. Don't do this if they're vomiting or having trouble breathing. If they are vomiting or having trouble breathing, help them into a comfortable position with their legs raised if possible. Pregnant people should be on their left side.

  • Tell the person to remain still and limit talking. Reassure them that help is on the way.

Step 2. Give epinephrine if available

  • If the person carries an epinephrine auto-injector to control anaphylaxis, help them use it.

  • Prevent any further contact with or exposure to allergen.

Step 3. Monitor breathing

  • Watch for signs of airway swelling, such as wheezing or swollen lips. With an extreme reaction, the person may have trouble getting any breath.

  • Do rescue breathing, if needed. In extreme cases, you may not be able to get air into the lungs.

Call 911

Call 911 right away if the person has any of the following. Or if they have a combination of mild or severe symptoms listed below:

  • Trouble breathing, shortness of breath, wheezing, or continued cough

  • A history of airway swelling (anaphylaxis)

  • Continued vomiting

  • Abdominal (belly) pain

  • Severe diarrhea

  • Lips, skin, or nail beds look pale, blue, purple, or gray

  • Feeling faint, dizzy, or confused

  • Weak pulse

  • Throat feels tight or hoarse

  • Trouble swallowing or talking

  • Swelling of the tongue or lips

  • Feeling of doom or feeling something bad is about to happen

  • Hives all over the body or redness

  • Loss of consciousness

Online Medical Reviewer: Deborah Pedersen MD
Online Medical Reviewer: Jessica Gotwals BSN MPH
Online Medical Reviewer: Rita Sather RN
Date Last Reviewed: 5/1/2022
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