This Vaccine Side Effect May Affect Your Whole Body, Doctors Say

You may want to prepare for this full-body reaction after your COVID shot.

Most Americans are now eligible for the COVID vaccine, and are also probably aware by now that there are a number of side effects that can result from the shot. Fortunately, the Centers for Disease Control and Prevention (CDC) assures that these adverse reactions are a normal response to your body building immunity, but they can still be unpleasant and unnerving—which is why it's always best to be prepared. And there's at least one lesser known side effect that could affect your whole body. Read on to find out which side effect you might notice from head to toe, and for more reactions to be aware of, If 1 of These 3 Body Parts Starts Swelling Up After Your Vaccine, Call a Doctor.

You could get a rash that covers your entire body after the COVID vaccine.

Measles, Women scratch the upper arm with one hand due to the numerous red pruritus., Measles is a disease that can spread easily.

A study published in the Journal of the American Academy of Dermatology on April 7 looked at 414 patients who reported one or more skin reactions after receiving a mRNA COVID vaccine between Dec. 2020 and Feb. 2021. The most common skin side effects included delayed large local reactions, local injection site reactions, urticarial eruptions (hives), and morbilliform eruptions, which are full body rashes that appear almost like measles.

"People can get full body rashes, and that can be surprising and a little scary, " Esther Freeman, MD, the study's senior author and the director of global health dermatology at Massachusetts General Hospital, told USA Today. And for more vaccine guidance, This Common Medication Can Make Your Vaccine Less Effective, Study Says.

However, a full body rash is usually harmless, just like other side effects.

Close-up of man suffering itching scratching neck standing outdoors in a park

As long as you experience a rash at least four hours after your vaccine, you should be fine. Any sooner than that and you could be experiencing a severe or immediate allergic reaction to the COVID vaccine, which the CDC says must be examined by a medical professional right away. According to the study, delayed skin reactions typically start a day or so after vaccination, but can also be delayed to seven or eight days later.

"For people whose rashes started four or more hours after getting the vaccine, zero percent of them went on to get anaphylaxis or any other serious reaction," Freeman explained. She added that the people who did get full body rashes "did extremely well" and "recovered."

"Importantly, allergic cutaneous symptoms reported in this study, such as urticaria, angioedema, and/or morbilliform eruptions, may not be caused by allergy to the vaccine but instead related to host immune response or an immunologic reaction to nonsteroidal anti-inflammatory agents commonly taken for pain and fever after vaccination," the researchers explained in the study. And for more COVID vaccine news delivered straight to your inbox, sign up for our daily newsletter.

This skin reaction most commonly occurred after the first dose.

Woman in purple blouse show off manifestation of skin allergy on her chest.

According to the study, more people experienced a full body rash after the first dose of the vaccine. Out of the patients who reported skin reactions after the Moderna vaccine, morbilliform was the fourth-most common skin reaction, occurring in 11 patients after the first dose and in seven after the second. For those who received Pfizer, morbilliform was the third-most common skin reaction, occurring in six patients after the first dose and in three after the second. And for more on the different reactions between doses, Doctors Are Warning You to "Be Prepared" for This After Your Second Dose.

Getting a full body rash does not mean you can't get the second dose of the vaccine.

Woman getting COVID vaccine

If you did experience a skin reaction—even a full body rash—after the first dose, don't let that deter you from the second dose. Freeman noted that those who experienced a full body rash "were able to go back and get their second dose."

"People can feel reassured about getting the second dose of their vaccine," she said. "Even if you have a pretty impressive rash after the vaccine, as long as it didn't start within four hours of vaccination you should feel comfortable getting the second dose."

According to the CDC, you should not get the second COVID vaccine dose in a two-dose series only if you have a severe allergic reaction or an immediate allergic reaction—no matter the severity—to the first dose. "An immediate allergic reaction happens within four hours of getting vaccinated and may include symptoms such as hives, swelling, and wheezing (respiratory distress)," the CDC notes. And for more advice on vaccine reactions, Doing This After Your Vaccine Can Make Side Effects Worse, Doctors Say.

Filed Under