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Allergies and Itching after COVID vaccine? Announcing Research Here

Results from 64,900 vaccines: How often are allergies and itching after COVID vaccine?

We’ll take a look at how common symptoms like itching after a COVID vaccine is.

Urticaria hives allergic reaction in systemic lupus erythematosus SLE

Hives (urticaria) photo credit: James Heilman, MD, Wikipedia, “Hives”

​Journal of the American Medical Association Research Study: March 2021

(reference and link to the study are at the bottom of the page)

Easy-to-Read Results Summary:

– Researchers did this study based on the fact that many are nervous to get the vaccines due to having allergies themselves and all the media-hype regarding allergic reactions causes some people to avoid the vaccines.

So… what is the truth?

  • Study was done at Massachusetts General Brigham (the Original Harvard hospital!)
  • Studied what happened the 3 days after the first vaccine (the time of highest chances for allergy symptoms)
  • 40% got Pfizer, 60% Moderna

Mild allergic reactions

  • 1 out of every 50 vaccines caused mild allergic reactions (itch, hives, swelling)
  • Moderna (2.2% of the shots caused mild allergy) vs Pfizer (2% of the shots): not much difference
  • 98% of all people had no allergic reactions at all (that is a nice, safe number)

Significant allergic reactions (anaphylaxis)

  • Occurred in 1 out of every 3700 Pfizer shots (i.e. .027% of the shots)
  • Occurred in 1 out of every 4300 Moderna shots (i.e. .023% of the shots)
  • In total, there were 5 anaphylactic reactions per 20,000 vaccines (that is a really safe number compared to many other drugs)
Moderna and Pfizer COVID-19 mRNA vaccines for lupus patients

Pfizer and Moderna were pretty similar in how often they caused allergic reactions: very low numbers

​Timing for significant allergic reaction (anaphylaxis)

– An average of 17 minutes after the shot
– The range was from immediately after the shot up to 2 hours later at the latest
Anaphylaxis severity
– 7 of the 16 patients had mild skin reactions
– 9 of the 16 patients had “measurable” but not life-threatening reactions
– 3 did not seek any medical attention
– 1 went to the ICU and recovered
– 9 out of 16 patients needed an epinephrine shot (EpiPen) and all recovered
– There were no severe anaphylactic reactions (having shock or requiring intubation)

Who was most likely to get anaphylaxis?

– Out of 16 patients in total, 5 (31%) had a history of anaphylaxis
– 10 out of 16 (61%) had a history of allergies (probably not significantly different than the usual population)

“I have a history of anaphylaxis, what is my risk?”

– Assuming there were 4000 individuals with severe food or drug allergies in this group (this is the expected #)
– Only 5 out of 4000 people with a history of anaphylaxis get an anaphylactic reaction (1 out of every 800)
– Knowing that this is a group of people who are used to planning for anaphylaxis and should have an EpiPen, and who know they have to use it when exposed to a known allergen (like me when I accidentally eat shrimp), that is an incredibly low number.
– I took my EpiPen with me when I got mine. No problems! Only 1 out of every 800 times would someone need to use it

Bottom lines

– Since the results were reported by the employees themselves, and not confirmed by doctors, we cannot ensure that these were truly anaphylactic reactions (people do tend to overestimate such responses = my opinion)
– The researchers, Harvard-famous allergy experts, stated, “… the overall risk of anaphylaxis to an mRNA COVID-19 vaccine remains extremely low”

If you have had an anaphylactic reaction in the past (like I have), I recommend:
– Just take your EpiPen and wait a while after your shot if you have had anaphylaxis before. However, don’t sweat it.

You have a higher chance of getting into a car accident on the way to the shot than you do of getting an anaphylactic reaction

Did you get your vaccine? How did you do?



Don Thomas, MD author of “The Lupus Encyclopedia” and “The Lupus Secrets


  1. I had my first Moderna dose and had no reaction except a sore spot on my arm where I got the injection.

  2. Moderna injections. Both shots: some pain and swelling at injection site (mild). Noticeable fatigue after first shot (Note: I’ve experienced far worse during lupus flares.). Joint pain after 2nd shot, but could have been result of weather change

  3. This is nice and reassuring to read!
    A bit off topic… but I’d love to know if there are any studies for vaccination of patients with mast cell disorders like MCAS?

  4. Kind of a straw man argument. I don’t think autoimmune patients are as worried about anaphylaxis shock or allergic reactions to the covid vaccine. It’s more like a fear of being seriously immune compromised at the time & fearing infections and honestly there have not been extensive studies on how an RNA vaccine might effect autoimmune patients…. Will it trigger our symptoms? Cause a flare?

    Are rheumatologists and patients discussing this on a case by case basis, bc some people in the community have have had COVID-19. These people might have natural immunity and not need a vaccine.

    • Thank you for your reading my post and commenting. Sharing ideas and research to help people make informed decisions based on actual data is so important.

      This post specifically addresses the results of a study addressing allergic reactions to the vaccines at a time when there truly was media hype about allergic reactions to the vaccines. This was not a post addressing flares in patients with autoimmune disease (though this is an important question).

      When we see a patient who is hesitant on getting a vaccine, my next step is to ask why they are hesitant and what their concerns are about the vaccine. Their answers range any where from a fear of an allergic reaction to a perceived lack in research on the vaccine, to even “a government conspiracy” (yes, I have heard this one). Interestingly, very few of my patients have specifically mentioned fear of a lupus flare. In fact, I can’t even remember any of them stating this. However, this may reflect my biased patient population. I am such a proponent of vaccines, that the vast majority of my patients do get their vaccines (after my continuous education and persistent in recommending them), and since they rarely ever flare afterward, this may not be their concern. This may be very different in online forums and support groups, where it may be a more common concern.

      Fortunately, we are not seeing a high number of flares in our patients. I have not seen any in my patients. A meeting I attended where rheumatologists were asked this question also did not show any large concerns. And the largest study to date in patients with autoimmune diseases also showed no increase in side effects or flares after vaccination:

      So, bottom line, as in all things dealing with patients, it is discussed on a case by case basis. I don’t know how else to practice good medicine.

      Also, please don’t think that natural infection in any way results in significant long lasting immunity, especially in patients with compromised immune systems. This has not been shown to occur in healthy people with stellar immune systems. And now with emerging mutant variants (such as delta and mu) natural long-lasting immunity is even less likely.

      Thanks for your comment and questions,

      Donald Thomas, MD

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