Penicillin Allergy

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Are You Actually Allergic to penicillin?

If you've ever had a reaction to penicillin, you've likely assumed you're allergic. You're not alone – 10% of people report being allergic to penicillin. However, only 1% actually are. Because of this, many people have needlessly lost access to an important class of antibiotics. 

Our bodies react to foreign substances in a variety of ways. Most of the reported penicillin reactions are side effects and do not represent a life-threatening allergy. This can change even if your doctor said you were allergic in the past. Most people who report a penicillin allergy, mainly when the reaction occurred years ago or as a child, can safely take penicillin. "Many people outgrow the allergy," says Dr. Jeanne Lomas, Director of Allergy and Immunology at WellNow Allergy.

Most patients benefit from testing to determine whether or not they are truly allergic to this class of drugs. In addition, penicillin challenge testing opens up useful treatment options for most people who previously thought they had a penicillin allergy.

Where can I get a penicillin challenge test done?

Infections can happen at any time, and often the safest antibiotic to treat these infections is penicillin. If you have been told you are allergic to penicillin, testing to determine if you are truly still allergic is available. WellNow Allergy offers penicillin testing in the following New York locations: 

Call or use our convenient online scheduling to your allergy test today.

What is penicillin?

Penicillin is a class of antibiotics that has saved millions since its first discovery. Penicillin is effective against a broad spectrum of bacteria. It's commonly used to treat respiratory tract bacterial infections, such as ear and sinus infections, strep throat, and pneumonia. 

What's the difference between an allergic reaction and other reactions? 

Allergies are the result of the body's immune system identifying a foreign substance – in this case, penicillin – as a threat. In response, the body creates allergic antibodies to find and remove the penicillin from your body. When this happens, the body releases histamine, which causes allergy symptoms.

As long as you still have antibodies for penicillin, an allergic reaction will be triggered if you retake penicillin. Antibodies can remain in your system for years, but they can also outgrow an allergy. In fact, half of the people allergic to penicillin are no longer allergic after 5 years, and most (80%) are no longer allergic after 10 years. 

Penicillin allergy symptoms are similar to other allergic reactions and can include rash/hives, swelling, cough, shortness of breath, or wheezing. However, life-threatening allergic reactions like anaphylaxis occur in just 1 in 3000 people who take penicillin. 

Adverse side effects are caused by the drug's action in your body. Penicillin can cause many side effects, the most common being nausea, abdominal pain, diarrhea, headache, and some non-allergic skin rashes. Side effects can often be minimized and may be manageable for those who would benefit from using penicillin.

Why should I get tested for a penicillin allergy?

By avoiding penicillin, a whole class of antibiotics becomes unavailable to you. Dr. Lomas says, "It is important to find out if you are truly allergic or not. The problem with leaving penicillin on your allergy list is that alternative antibiotics are often more costly and may cause more side effects and complications. In short, simply having a label of penicillin allergy on your chart can be detrimental to your health."

Getting tested for penicillin allergy is a low-risk way of seeing if you can open your treatment options now and in the future. 

How do I find out if I'm allergic to penicillin or not? 

To find out if you're allergic to penicillin, make an appointment with an allergist. Your allergist will start by asking about your medical history. This will include information about when you reacted to penicillin and what symptoms you had. After taking your history and performing a physical examination, your allergist may recommend allergy testing.

Your allergist may first perform a penicillin allergy skin test. This includes a small prick of the skin to certain substances, including penicillin. If there is no reaction, the prick test is followed by an intradermal test which involves injecting a small amount of penicillin under your skin with a tiny needle. If you are allergic, an itchy red bump will appear at the injection site. 

If your skin doesn't react to the skin test, you are unlikely to be allergic. An oral medication challenge is required to rule out the possibility of an allergy. 

What is a penicillin challenge test?

An oral medication challenge is a definitive way to prove whether a patient can tolerate penicillin and rule out a life-threatening allergic reaction. For a penicillin challenge, most patients are given a dose of amoxicillin by mouth. 

Amoxicillin is the most prescribed and used oral penicillin antibiotic. After the dose, you will be monitored for at least an hour. If no allergic reaction occurs, you will be considered not allergic to penicillin, and the medication will be removed from your allergy list.

If a reaction does appear, you will be treated for your symptoms and advised about your allergy.

Occasionally, if the reaction occurred long ago (more than 10 years) and consisted of only a rash and no additional high-risk symptoms, a direct oral challenge may be an option. A direct oral challenge is performed with amoxicillin as described above, but without doing skin testing beforehand. This procedure is only done if the risk is deemed low enough. For more information, speak with an allergist to determine which type of testing is best for you.

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