Penicillin Allergy


The correct diagnosis depends on a comprehensive examination and the right diagnostic tests. The use of less suitable or more costly antibiotics can result from a misdiagnosis of penicillin allergy.  After reviewing your symptoms, your healthcare provider will recommend immediate treatment if your symptoms are sufficiently severe to threaten your life.

  • Physical examination: The healthcare provider will conduct a physical examination; they will inquire about your symptoms and request further testing.
  • Skin tests: During a penicillin allergy skin test, an allergist or nurse uses a tiny needle to apply a small amount of penicillin to the skin, then waits about 15 minutes to observe any reaction. A positive reaction is indicated by a red, itchy, elevated bump. While a negative test result generally suggests a low likelihood of penicillin allergy, interpreting such results can be complex due to certain drug reactions not being detectable through skin tests.
  • Scratch test: Your healthcare provider will drop two component of penicillin to your skin during an allergic scratch test. It makes a scratch through every drip. The healthcare provider will check for skin reactions, such as skin discoloration, itchy skin, and hives, after 15 minutes.
  • Graded challenge: If there’s uncertainty about a penicillin allergy, a graded challenge may be employed, involving the administration of progressively increasing doses of the suspected penicillin, through five levels, starting with a very small amount and incrementally reaching the therapeutic dose. Successfully tolerating this dose without any adverse reaction signifies no allergy to that specific penicillin, thus clearing its use. For those allergic to a particular penicillin, a challenge with an alternative penicillin or a cephalosporin, chosen for their chemical properties that reduce the likelihood of an allergic reaction, may be suggested. This procedure is meticulously monitored by medical professionals to provide immediate care for any adverse reactions, ensuring that supportive care services are at hand for patient safety.


Your healthcare provider is tasked with overseeing the management of treatment for a penicillin allergy, which may involve:

  • Discontinue: The initial course of treatment if your healthcare provider finds that you have a penicillin allergy, or a suspected allergy, is to stop taking the medication.
  • Antihistamines: In order to prevent immune system chemicals activated during an allergic reaction, your healthcare provider may prescribe an antihistamine or suggest an over-the-counter antihistamine like diphenhydramine (Benadryl).
  • Corticosteroids: Corticosteroids can be administered orally or intravenously to address inflammation linked to more severe reactions.
  • Treatment of anaphylaxis: An instant epinephrine injection and hospital treatment are necessary for anaphylaxis in order to sustain breathing and blood pressure.
  • Alternative medications: If you are allergic to penicillin, there are alternative antibiotics that you can take. Should a healthcare provider recommend any medication, let them know that you are allergic to penicillin. Most people don’t necessarily experience an allergic reaction to other antibiotics if they have an allergic reaction to penicillin.
  • Drug desensitization: If no alternative antibiotic treatments are available, doctors may recommend drug desensitization to enable patients to undergo a course of penicillin. This method involves administering initially very small, then progressively larger doses of the medication every 15 to 30 minutes over several hours or days until the desired dosage is reached without adverse reactions, allowing the treatment to continue. Throughout this process, patients are closely monitored and provided with supportive care to manage any reactions. It’s crucial for patients to adhere strictly to the prescribed regimen to maintain tolerance throughout the treatment. However, should penicillin be needed in the future, the desensitization process must be repeated, and it’s important to note that this approach does not guarantee success and carries a risk of serious reactions.