6 Ways to Prevent Arm Soreness after a Vaccine

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Whether you’re gearing up for a flu shot, a COVID-19 booster or any other immunization, there’s one thing you’re probably banking on — a sore arm. But did you know there are ways to prevent or limit arm soreness? Christopher Ketter, DO, UnityPoint Health, explains what you can do to keep that arm feeling top notch after a shot.

Why Does My Arm Hurt after a Shot?

Your arm will likely hurt after a vaccine, like the flu shot, for two primary reasons. One is because you got a needle put in your arm muscle (deltoid), and a small amount of fluid injected. That causes a local inflammatory response — swelling. 

“The injection is deposited in the muscle of the arm, due to there being less fat in this muscle than, say, the gluteus muscle (butt), which can capture the vaccine solution but not let it do its thing,” Dr. Ketter says.

The second, more complicated, reason your arm hurts is due to how your whole body responds to a vaccine. They’re designed to start an immune response, which naturally causes an inflammatory reaction in your body. As that happens, the body makes and delivers antibodies to the injection site. 

“It’s normal for some vaccines to hurt more than others. Overall, symptoms usually last less than a few days. If your pain lasts longer, or becomes more severe, contact your doctor,” Dr. Ketter says.

6 Ways to Reduce Arm Soreness from a Vaccine

  • Relax. Flexing the arm during the injection can cause more damage and pain. And, if you’re nervous, you might be doing it without even knowing. Consider distracting yourself by looking away, closing your eyes or having something to watch during the injection. Deep breaths can also help you relax.
  • Move, move, move. Moving your arm will help disperse the liquid (injectate) put in your muscle and, in turn, will help with muscle soreness. An easy exercise you can try to increase movement is a lateral deltoid raise. Place your hands (palms down) at your sides. Then, lift your arms straight out to the side until you get to shoulder level. After your vaccine, try doing three sets of 10 raises a few times throughout the day.
  • Stretching. Try stretching your shoulder more than normal to help reduce inflammation. One good option is an across the chest stretch. To do it, put your sore arm across your chest. Place it in the crease of your opposite elbow and hold. 
  • Ice. Icing in short intervals throughout the day can help reduce swelling, which will reduce soreness.
  • Over-the-counter medication. Acetaminophen or Ibuprofen after your shot can help reduce inflammation and soreness. Since the vaccine is trying to stimulate an inflammatory and immune response, and these over-the-counter medications limit that, it’s best not to pre-treat for pain before your vaccine.
  • Avoid Strenuous Exercise. Stick with lighter aerobic exercise and strength training immediately after any vaccines. High intensity activities can worsen the arm soreness.

Which Arm Should I Get a Shot in?

“The jury is out on this one. It comes down to preference and what you plan to do that day. Moving the arm helps reduce pain, so the dominate arm could be beneficial. But, if you’re doing a lot that day, you may want to consider the non-dominate arm, so the pain doesn’t hinder you,” Dr. Ketter says.

However, if you’re getting two vaccines at the same time (like the COVID-19 vaccine and the flu shot), you’ll have to get them in different arms. That’s standard protocol, so you can monitor any differences in how your arm responds.

“Overall, having a sore arm for a day or two is a small price to pay for avoiding a trip to the hospital, or worse. Talk to your doctor to make sure you’re caught up on all the age-appropriate vaccines,” Dr. Ketter says.