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, 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

A severe (systemic) reaction affects the entire body. In extreme cases, the airways from mouth to lungs may swell (anaphylaxis). The reaction may happen right away or over several hours.

Step 1. Calm the person

  • Help the person into a comfortable position. Prop up his or her head to help with breathing.

  • Tell the person to remain still and limit talking.

  • If the person carries medicine (epinephrine) to control anaphylaxis, help him or her use it.

  • Prevent any further contact with or exposure to allergen. 

Step 2. 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 While you wait for help:

Call 911 right away if the person has any of the following:

  • Trouble breathing

  • A history of airway swelling (anaphylaxis)

  • Reassure the person.

  • Treat for shock or provide rescue breathing or CPR, if needed.

When to seek medical help

An allergic reaction may become more serious over time. Seek medical help if any of the following is true:

  • A rash or hives covers the face, genitals, or most of the body.

  • An entire body part, such as an arm or leg, swells.

  • The tongue or lips begin to swell.