Are You Absolutely Sure You Have a Penicillin ALLERGY?

Do you really have a penicillin allergy?

Here’s why I ask:  There is a 90% chance you aren’t REALLY allergic to penicillin anymore!

I’ve made this post quick to give you the answers to remove your penicillin allergy (and added some extra information at the end if you really LOVE reading about penicillin reactions and antibiotic resistance… I even tried to make it interesting!)

If you have a penicillin allergy, I want to ask you a one question:

What if I told you there was a 90% chance you DON’T have a penicillin allergy?

What was your first thought to that statement?

  • Smile  If it got you excited that you might clear your penicillin allergy and stop being limited in your treatment options, then this article is for you!
  • Flirt male  If I intrigued you… but you’re kind of suspicious that I pulled click bait on you… keep reading and you’ll see my statement is fact (and a real fact, not an “alternative fact”)
  • Annoyed  If you’re skeptical because you remember your penicillin reaction (or you were told stories about your penicillin allergy when you were a kid) then this article is also for you.
  • Steaming mad  Finally, if your immediate response was to scoff at this and think to yourself that “I’ll pry your penicillin allergy out of your cold dead hands” then… maybe I can convince you otherwise?!

If you don’t have a penicillin allergy, I have something for you:

If you want to impress your friends, you could read a few facts and drop them the next time someone talks about penicillin allergies!  Or you can SHARE the post and then leave… that’s ok too.

Who should read this article?

I have written this article for ANYONE with penicillin allergy:  both adults and children with penicillin allergy!

With this in mind, you should read this article:

  • If you are allergic to penicillin
  • If your son or daughter has a penicillin allergy
  • If you’re a healthcare provider, then please read this article… TWICE
  • If you like having facts that can prove your friends (or annoying family members) wrong
  • And here is a brand new category:  if you are a hospital administrator or manage a large medical group then this article could save you and your organization a lot of time and money (oh and provide better healthcare to your patients!)

If you don’t fall into these categories, then you can stop reading here (although… might I interest you in a thrilling tale of How to Take Care of a Sinus Infection the Right Way?  Or perhaps figuring out whether you have a food allergy vs. food intolerance?  Or you could just watch my baby laughing.)

Why should you care about penicillin allergies?

Don’t leave the article just yet… give me 1 more minute!

I understand and sympathize with the fact it’s hard to care about penicillin allergies.  Even if you have them, it seems easy to just “avoid penicillin.”  And the news media doesn’t always help.

a sarcastic photo about internet trends related to penicillin allergy
Hey, Intern – write a story about dabbing. Or penicillin allergy

After all, doesn’t it seem like every year some intern reporter has to do these three reports to fill the air:

  1. Blah blah blah… something about the bird flu
  2. Coverage of some new trend that the kids are doing (like planking, or the ice bucket challenge, or dabbing)
  3. Something about antibiotic resistance “being the end of the world as we know it” (and we don’t feel fine)

I get it!  You’re tired of these type of articles.

But here is why mine is different:

  1. I am writing this as an allergist and I’m supporting it with facts and a cool video
  2. I will do the work for you (I’ll take your history and find you an allergist in your area for you!)
  3. I don’t think antibiotic resistance will be the end of mankind (everyone who knows me knows I fear robots far more than antibiotic resistance)
  4. Also, I really, really like telling people they’re wrong

Let me jump straight into it.

Penicillin allergies are boring
Penicillin reactions can be boring.  I promise I’ll make this article interesting for you!

Are you SURE your reaction REALLY a penicillin allergy?!

Wait, am I saying your reaction wasn’t real?

Of course not.  About 10% of the population has ‘penicillin allergy’ listed on their medical record… and I don’t think ‘claiming penicillin allergy’ is such a cool thing to do that 30 million people all did it.

What I think is:

  1. We, as medical providers and as patients, tend to over-diagnose adverse reactions as allergies
  2. Many of us don’t know what our reaction was but just keep saying we’re ‘allergic’
  3. About 80% of of people with real, life-threatening penicillin allergy lose it after 10 years

So how can you tell?

I’ve created this infographic to help.


Why am I picking on penicillin?

Easy.  Of the 10% of the population has a “penicillin allergy,” 90% of those people DO NOT actually have an allergy.

And penicillin allergy is EASILY tested and diagnosed!

As an allergist, I can remove the penicillin allergy in 9 out of 10 allergic people in about 2 hours of work! Here’s what happens:

  1. First, I take your medical history.  I’ll try to get as many details as possible… but I know it’s hard to remember (this is the first visit, and the procedure is on a second visit).
  2. Second, I will do a scratch allergy test to the core components of penicillin
    • A negative test will rule out penicillin allergy in about 95% of people
    • This might be enough to clear you of your penicillin allergy!
  3. Third, I sometimes need to do an oral challenge after this to make sure you’re not allergic
    • This will raise your answer close to 100%
    • And then you never have to worry again!

If I’ve sold you or if you’re interested in learning more, I’ve made it easy for you.  Just click the link below and I will do this to help you out (what could be easier?):

  • I’ll ask and then review your history to give you my best pre-test guess
  • I’ll look up allergists in your area, review their credentials and give you some names to consider
  • That’s it!  What do you have to lose?

Take the “Do I REALLY have a penicillin allergy” QUIZ

The theory and practicality of antibiotic resistance: what is the problem?

Still reading?  I am impressed with your desire to learn more (or maybe you find this article such a train wreck you have to keep reading to see what happens next?)

a picture of batman and the joker trying to spice up penicillin reactions
Maybe a Batman reference can make penicillin allergy more interesting

Antibiotic resistance (specifically penicillin allergy) is a legitimate problem that IS getting worse.  And it is a problem that directly and indirectly affects all of us (not a hyperbole!)

Why is there antibiotic resistance?

Think of it this way:

  • If you have regular police officers, you get regular bad guys with guns
  • If you police officers wearing bullet proof armor, you get bad guys with armor piercing rounds
  • If you have Batman, you get the Joker
  • If you have a great Batman (thanks, Christopher Nolan), you get Heath Ledger as the Joker!

Antibiotic resistance is just a game of cat and mouse where the bacteria are evolving faster than we can make new antibiotics!

But even a Batman analogy can’t make this interesting.

So here is a video which shows it (it’s worth a fast watch… it’s less than 2 minutes)

How having a penicillin allergy directly affects you

If you have a penicillin allergy, your doctor cannot give you any penicillin antibiotic (or, for many people, cephalosporins due to cross reactions).  This means that the antibiotics they give you:

  • Might not be as effective (seen often with sinus infections and zpacks/azithromycin)
  • Might cost you more (some patients, a penicillin is $10 while a fluroquinolone is >$75)
  • Might have more side effects (risk of bowel infection with clindamycin, risk of tenon rupture with fluroquinolones)

Not convinced?  Fair enough.  Maybe I can convince you to look at the bigger picture?

How other people with penicillin allergy directly affects you

allergic to penicillin costs
Penicillin allergy costs DO effect all of us. (Pic source)

I initially wrote this with a lot of numbers:  700,000 people/year die from antibiotic resistant infections, expected 10 million deaths per year (more than cancer) from antibiotic resistance expected in 2050.

But these numbers are a little too large and too extrapolated for me to ‘feel the weight of antibiotic resistance.’  And it sounded like every other cliche article about the subject.

So think of it this way:

  • If someone does not have a penicillin allergy but avoids penicillin, it makes YOU more likely to encounter one of these resistant strains of antibiotics.
    • In sinus infections, we already need to give YOU stronger antibiotics because antibiotic resistance is present in >50% of infections.
    • So you ALREADY have to pay more because of someone else’s antibiotic allergy
  • Plus, all of this causes a higher cost of healthcare.
    • It is true that the penicillin allergic person bears the brunt of this cost (with higher medication costs.)  But the costs do add up for the insurance companies.
    • And as a result, insurance companies increase all our rates to make back their lost bazillions of dollars.

From a pure economic perspective, this problem is affecting all of us and not just people with penicillin antibiotic allergies!

What are symptoms of penicillin allergy?

If you have a penicillin allergy, it is the same as having an allergic reaction/anaphylaxis.

Usually the symptoms do NOT happen the first time you take penicillin.  Instead, you’ve “taken the medicine before without problems” but this time was different.

Hives happens in about 90% of people and most of the time you’ll stop the penicillin at that point.  So you may not notice all the symptoms of full penicillin allergy.

These are the typical penicillin allergy symptoms:

  • Hives–which are very itchy, red, blotches or welts.
    • The rash may last for more than a day, but each individual hive should last <24 hours
    • NOTE: if you have only hives, you might have a penicillin allergy or might not.  It’s safest to do allergy testing to know for sure.
  • Swelling in the face, tongue, hands, feet, or groin
  • Abdominal pain, nausea, vomiting
  • Shortness of breath, wheezing, coughing or difficulty breathing
  • Lightheadedness, dizziness, feeling like you might pass out
  • Feeling of impending doom (always my favorite)
  • “I woke up in a hospital” (yes, I get this quite a bit actually)

If you had any symptoms like this, you most likely had a true allergic reaction.

The good news:  There is an 80% chance you will “outgrow” your penicillin allergy after 10 years.

What are symptoms of penicillin adverse reaction?

Want the cop-out answer?  Any symptom that is not penicillin allergic reaction.

But I can do better.  The most common penicillin adverse reaction symptoms are:

  • Red, flat rash–often across chest, might be itchy, lasts > 24 hours
  • Nausea or vomiting, or just abdominal pain
  • Headache or body aches
  • Fatigue
  • Any other non-allergic reaction

If you think you had a penicillin adverse reaction, then this is not the same as a penicillin allergy.  So why not get tested and know for sure?

If you’re confused or unsure… no problem.  Just let me know your symptoms and I’ll give you my best answer!

How do you diagnose penicillin allergy?

As I covered in my What is an Allergy blog if you have a true penicillin allergy then you body has made an immune response against a part of the penicillin that is found on all penicillins.

Your immune system now thinks it is ‘protecting you’ against the horrors of penicillin.  (Thanks, body!)

But we use this to diagnose penicillin allergy.

As an allergist, we can skin test or blood test to see if you have an allergic reaction to penicillin.  From there, a good allergist will either diagnose you with penicillin allergy OR, if possible, remove that diagnoses from your chart (although you might have to do a penicillin oral challenge)

what medications avoid with penicillin allergy
Penicillin allergy often also requires cephalosporin avoidance

What antibiotics do you need to avoid in a penicillin allergy?

If you have a true penicillin allergy, then you need to avoid ALL penicillins.  This includes:

  • Penicillin (obviously)
  • Amoxicillin
  • Ampicillin
  • Augmentin
  • Other penicillin class antibiotics

BUT… there is also a chance that if you have a penicillin allergy, you ALSO have to avoid the cephalosporin class of antibiotics (about 7-10% of people with penicillin allergy have cross-reactions with cephalosporins).

Note:  This is why it’s important to clear you of a false penicillin allergy.  You have the chance to get back TWO different antibiotic classes!

What should you do to clear your penicillin allergy?

So you’re believing… excellent!

What you need to do next is see an allergist with the purpose of clearing your penicillin allergy.

  • Call first and make sure they do penicillin testing… not all allergists do
  • Make sure it’s a board certified allergist and not an ENT allergist or primary care allergist.  This is a more specialized test and you need the real specialist.
  • Ask ahead of time how many visits and how long the visits are.
    • For me, the initial visit is 30 minutes and then I do it all in a follow up visit of about 2 hours.
    • I’ve seen some who do it all on one visit.  Or some who spread it out over a month (why do this to your patients?!)

But you can fill out this questionnaire and I will review your symptoms and give you a list of some good allergists in your area to save you some of the guesswork:

Make this easy on me:  review my symptoms and give me a list of allergists


You have learned that 90% of people who have ‘allergy to penicillin’ listed on their chart don’t have a penicillin allergy any more.  This is most likely due to:

  1. You had hives while taking penicillin… but the hives were due to the infection
  2. You had a penicillin adverse reaction and were mis-diagnosed as penicillin allergy
  3. You had a legitimate penicillin allergy… but 80% of people will outgrow this within 10 years

Because of this, I tried to show you why getting an allergy test to clear your penicillin allergy was important.  I even offered to review your symptoms and find an allergist near you to call.

If you were an advanced reader, and I captivated you with my thrilling tales of penicillin reactions, you also learned:

  • The theory and practicality of antibiotic resistance and watched a cool video
    • The direct impact of having a penicillin allergy
    • The indirect impact of other people having penicillin allergies
  • The symptoms of penicillin allergy vs. penicillin adverse reaction
  • How an allergist diagnoses penicillin allergy
  • What antibiotics to avoid if you have a penicillin allergy
  • And what to do to clear your penicillin allergy

I hope the article was enjoyable, and that you found the information you were looking for.  If so, you can like my Facebook page and get more great tips like this:

Next Steps

If you made it this far, your next step will be to make an appointment with a local allergist and figure out your answer (and then, come back here and let me know how it worked).

If you found this article helpful, consider sharing it with your friends and family.


If you have questions, please email me or comment below or on my Facebook page.  Remember, for every question you have, many other people also have it but are too afraid to write a comment.

Did you enjoy that article? Here are some more I think you'd enjoy

U.S. Epipen Recall: What you NEED to Know It seems EpiPen can't get out of the news lately. This time it's because Epipens in the U.S. are being recalled due to a malfunction causing them NOT...
How to Safely Travel with Food Allergies, Asthma, Eczema or Allergies Traveling is hard. Traveling with allergies is harder. This post helps you be as safe as possible when traveling with allergies, asthma, food allerg...
Be a Sinus Rinse Expert with these Secrets Get the BEST, insider answers to your sinus rinse questions. I'll share my years of allergy experience to help you feel the best with your sinus rins...
The One Epipen Trick your Pharmacist Doesn’t Want You to Know There is one cost-saving epipen trick that everyone should know... but you're never told. This article reviews one easy trick that everyone should rea...
  • Hello! I enjoyed reading your article! My oldest child who is almost 12 yrs old was told she was allergic to amoxicillin when she was about 4 years old. She broke out in hives after day 7 of her 10 day medication schedule. She saw an allergist today who recommends she also do testing to make sure. He gave me great info just like your article. I appreciate the time and effort that you took to write it! Thank you!

    • Thank you so much!

      Until a few years ago it was difficult to do good penicillin testing because the skin test, Prepen, wasn’t available. Now that it is its really easy to get the right answer. I hope everything goes well with your daughter and the penicillin challenge (my guess is that she’s a low risk for true allergy, which is great).

      If I can help you in any other way, please just let me know. And also, if you know anyone else with penicillin allergy, share your experience and hopefully you can help them out too!

  • >