Many people who report having a penicillin allergy don't have a true allergy. They may have had a reaction to penicillin, such as certain types of rash, but not all reactions are allergies. Penicillin allergy symptoms include:

  • Hives
  • Rash
  • Itchy skin
  • Wheezing
  • Swollen lips, tongue or face (angioedema)

Anaphylactic reactions

The most serious allergic reaction to penicillin is an anaphylactic (an-uh-fuh-LAK-tik) response, which can be life-threatening. Anaphylactic reactions develop immediately after penicillin exposure in highly sensitive people. Signs and symptoms include:

  • Difficulty breathing
  • Wheezing
  • Drop in blood pressure
  • Swelling of the throat or tongue
  • Dizziness
  • Loss of consciousness
  • Rapid or weak pulse

When to see a doctor

Seek emergency medical care if you think you or someone else is having an anaphylactic reaction.

If you have less severe reactions after taking penicillin, talk to your doctor. If possible, see your doctor when the allergic reaction is occurring. This will aid in making a diagnosis.

Dec. 15, 2011

You Are ... The Campaign for Mayo Clinic

Mayo Clinic is a not-for-profit organization. Make a difference today.