If I had an allergic reaction to mRNA vaccination, can I switch to J&J?

Co-Author: Jenna Resnik

According to the CDC, there are several reasons why people should talk to their doctor before getting a second dose of an mRNA COVID-19 vaccine. These reasons are: 

  • You had a severe allergic reaction to your first dose. A severe reaction includes anaphylaxis (difficulty breathing that requires medication), swelling of your tongue and throat, or a rash involving your mouth, nose, or eyes.
  • You had an immediate reaction (within 4 hours) to your first dose, even if it wasn’t severe. Mild reactions include a rash or swelling that goes away quickly.

Your doctor will help determine if your reaction was likely related to the vaccine, and if it was severe or not. Your doctor may want you to see an allergist before making a final decision. He or she can also consult the Clinical Immunization Safety Assessment COVIDvax for additional guidance.

If you had a severe reaction, you should probably not receive another dose of an mRNA vaccine, but might be eligible for the J&J vaccine. If your reaction was mild, it might still be OK to get a second dose of an mRNA vaccine. But don’t make this call on your own; make sure you talk to your doctor.

If you do proceed with the J&J vaccine, it should be at least 28 days after the mRNA vaccine. And it should be given in a setting where appropriate monitoring and treatment can be provided if needed.

Last update: October 29, 2021, 10:22 am ET

Science review: GSN, JAB