Mayo Clinic Health Library

Insect bites and stings

Updated: 03-01-2012

Signs and symptoms of an insect bite result from the injection of venom or other substances into your skin. The venom causes pain and sometimes triggers an allergic reaction. The severity of the reaction depends on your sensitivity to the insect venom or substance and whether you've been stung or bitten more than once.

Most reactions to insect bites are mild, causing little more than an annoying itching or stinging sensation and mild swelling that disappear within a day or so. A delayed reaction may cause fever, hives, painful joints and swollen glands. You might experience both the immediate and the delayed reactions from the same insect bite or sting. Only a small percentage of people develop severe reactions (anaphylaxis) to insect venom. Signs and symptoms of a severe reaction include:

  • Nausea
  • Facial swelling
  • Difficulty breathing
  • Abdominal pain
  • Deterioration of blood pressure and circulation (shock)

Bites from bees, wasps, hornets, yellow jackets and fire ants are typically the most troublesome. Bites from mosquitoes, ticks, biting flies, ants, scorpions and some spiders also can cause reactions. Scorpion and ant bites can be very severe. Although rare, some insects also carry disease such as West Nile virus or Lyme disease.

For mild reactions

  • Move to a safe area to avoid more stings.
  • Remove the stinger, especially if it's stuck in your skin. This will prevent the release of more venom. Wash the area with soap and water.
  • Apply a cold pack or cloth filled with ice to reduce pain and swelling.
  • Try a pain reliever, such as ibuprofen (Advil, Motrin, others) or acetaminophen (Tylenol, others), to ease pain from bites or stings.
  • Apply a topical cream to ease pain and provide itch relief. Creams containing ingredients such as hydrocortisone, lidocaine or pramoxine may help control pain. Other creams, such as calamine lotion or those containing colloidal oatmeal or baking soda, can help soothe itchy skin.
  • Take an antihistamine containing diphenhydramine (Benadryl, others) or chlorpheniramine maleate (Chlor-Trimeton, others).

Allergic reactions may include mild nausea and intestinal cramps, diarrhea, or swelling larger than 4 inches (about 10 centimeters) in diameter at the site, bigger than the size of a baseball. See your doctor promptly if you experience any of these signs and symptoms.

For severe reactions
Severe reactions affect more than just the site of the insect bite and may progress rapidly. Call 911 or emergency medical assistance if the following signs or symptoms occur:

  • Difficulty breathing
  • Swelling of the lips or throat
  • Faintness
  • Dizziness
  • Confusion
  • Rapid heartbeat
  • Hives
  • Nausea, cramps and vomiting

Take these actions immediately while waiting with an affected person for medical help:

  1. Check for medications that the person might be carrying to treat an allergic attack, such as an autoinjector of epinephrine (EpiPen, Twinject). Administer the drug as directed — usually by pressing the autoinjector against the person's thigh and holding it in place for several seconds. Massage the injection site for 10 seconds to enhance absorption.
  2. Loosen tight clothing and cover the person with a blanket. Don't give anything to drink.
  3. Turn the person on his or her side to prevent choking if there's vomiting or bleeding from the mouth.
  4. Begin CPR if there are no signs of circulation, such as breathing, coughing or movement.

If your doctor has prescribed an autoinjector of epinephrine, read the instructions before a problem develops and also have your household members read them.

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