Thankfully, Zehra, extra doses of vaccine generally cause no problem. And with measles, mumps, and rubella (MMR), it is best for children to receive two doses. The 2nd dose of the MMR is recommended routinely at 4 to 6 years of age but may be given at any time, provided at least 4 weeks have passed since the 1st dose and that both doses are received after the first birthday. Being a parent presents many opportunities to worry, but this is a time to relax.