One of the most common side effects from vaccines, particularly the seasonal flu vaccine, is a sore shoulder. This soreness can be worrying, but in most cases, there is nothing abnormal about some soreness, swelling, and redness at the injection site. However, you don't just have to suffer through it.
If you would like to prevent (or at least minimize) that pain, try the following:
Immediately after the injection, move your arm around. This is something that medical professionals will often suggest. Take that suggestion as medical advice. Keeping it still may be the worst thing you can do.
For the first couple of days take an over-the-counter pain reliever, like ibuprofen. Please only take pain relievers you have experience with and can tolerate.
Place an ice pack on the site, to help reduce any swelling.
Try rotating a warm pack on the injection site.
Any pain or swelling you have from a vaccine injection should go away within two to three days. If it does not, you should inform your healthcare provider. Other side effects which are sometimes (if rarely) experienced include an allergic reaction or an injury from an improper injection. The latter is called a shoulder injury related to vaccine administration or SIRVA. A SIRVA has nothing to do with the vaccine inside the needle, and everything to do with how the needle is placed in your shoulder.
If you do have an injury from the vaccine administration, you may require medical attention. If your shoulder pain lasts longer than 2 or 3 days, please seek the advice of your doctor.
If it turns out to be SIRVA or any other injury related to the vaccine, there is a program that ensures you can be compensated for that injury. It is called the Vaccine Injury Compensation Program or VICP. If you have been injured by a vaccine or its administration, you should contact an attorney experienced with the VICP as soon as possible.