Measles is caused by a virus. The measles virus is highly contagious and spreads through respiratory droplets when an infected person coughs or sneezes. Symptoms typically begin with a high fever, cough, runny nose, and inflamed eyes, followed by a red rash that usually starts on the face and spreads to the rest of the body. Complications from measles can include pneumonia, encephalitis, and other serious health issues. Vaccination is the most effective way to prevent measles and its complications. The measles vaccine is often combined with mumps and rubella vaccines in the MMR vaccine, which is recommended for children and adults who have not been vaccinated.