MMR Vaccination Side Effects
In most cases, the MMR vaccine (officially known as M-M-R® II) does not cause side effects. If reactions do occur, they are generally mild and easy to treat. In clinical studies, the most common side effect seen with the MMR vaccination (and other measles, mumps, or rubella vaccines) was temporary joint pain or stiffness -- this was reported in up to 25 percent people. Other common side effects included fever and mild rash.
In rare cases, a person may experience serious side effects of the MMR vaccination. These potentially dangerous problems should be reported to a healthcare provider right away. For example, if you or your child develops a high fever, difficulty breathing, hives, or paralysis, contact your healthcare provider immediately.
If your child has recently been vaccinated and is showing any unusual behavior changes, aside from the usual fussiness that typically occurs after vaccinations, or if he or she has been crying persistently for more than three hours, notify your child's healthcare provider.
(Click MMR Vaccine Side Effects for a more in-depth list of adverse reactions to this drug. This article also looks at why it can be difficult to tell if some problems are actual side effects of the MMR vaccination.)