Early signs of the disease include flu-like symptoms such as fatigue, lack of appetite, headache, pain in the arms and legs as well as fever. A typical symptom is the painful, inflammatory swelling of the parotid glands, which may occur on one or on both sides. The swelling usually persists for about three to eight days. The salivary glands in the mandible and/or under the tongue as well as the adjacent lymph nodes may also be enlarged. In at least one-third of the cases, the infection causes no or few symptoms. Especially children under the age of five often only produce symptoms similar to those of a common cold. For this reason, mumps goes undetected in many cases.
The risk of developing complications or late effects increases with age. Up to ten percent of all patients develop meningitis, which may manifest itself by severe headache, neck stiffness and vomiting. A less common complication is inflammation of the brain, which may cause lasting damage such as paralysis and can even have a fatal outcome in isolated cases. One in 20,000 patients may suffer hearing impairment or deafness. About one in three male patients after puberty develop orchitis as a result of mumps, which manifests itself by another rise in body temperature and tenderness on pressure affecting one or both testicles, and may cause a limitation to or, in rare cases, loss of fertility. In women, inflammation of the mammary glands or ovaries is also possible. Inflammation of the pancreas may occur as another complication.
