The hallmark symptom of mumps is painful swelling along the jawline, caused by inflammation of the salivary glands just below and in front of the ears. This swelling typically appears 16 to 18 days after exposure to the virus, though the incubation period can range from 12 to 25 days. About 20% of unvaccinated people who catch mumps never develop any symptoms at all, which means you can spread the virus without knowing you have it.
Early Symptoms Before the Swelling
Before the characteristic jaw swelling appears, mumps often starts with a few days of vague, flu-like symptoms: low-grade fever, headache, muscle aches, fatigue, and loss of appetite. These early signs are easy to mistake for a cold or mild flu, and many people don’t suspect mumps until the swelling begins.
What the Jaw Swelling Looks and Feels Like
The swelling affects the parotid glands, the large salivary glands that sit just in front of each ear along the jawline. As the glands swell, the tissue pushes the earlobe up and outward. In more pronounced cases, the angle of the jawbone below the ear disappears entirely, and you can no longer feel the jawbone through the skin. The face takes on a characteristic puffy, “chipmunk cheek” appearance.
The swelling is tender to the touch and often makes chewing or swallowing painful. Acidic foods and drinks can make the pain worse because they stimulate saliva production, which puts pressure on the inflamed glands.
In about 75% of cases, both sides of the face swell, though one side often swells before the other. In the remaining 25%, only one side is affected. About 10% of people also develop swelling in smaller salivary glands located under the floor of the mouth, which can cause additional discomfort under the chin or tongue.
How Long Symptoms Last
The jaw swelling usually peaks within one to three days of appearing, then gradually subsides over the following week. Most people feel significantly better within 10 days of symptom onset. You’re considered contagious from about two days before the swelling starts until five days after it appears, though the virus can be present in saliva for a wider window, up to seven days before and nine days after swelling begins.
Complications That Cause Additional Symptoms
Most mumps cases resolve without lasting problems, but the virus can spread beyond the salivary glands and cause inflammation in other organs. The risk of complications is higher in adults than in children.
Testicular Inflammation
Orchitis, or swelling of the testicles, is the most common complication. It affects up to 40% of young adult men with mumps and typically shows up about a week after the jaw swelling begins. Symptoms include testicular pain, swelling, and tenderness, sometimes with scrotal redness and a new round of fever and headache. It usually affects only one testicle. While orchitis is painful, it rarely causes infertility.
Ovarian Inflammation
Women can develop oophoritis, inflammation of the ovaries, which causes lower abdominal pain and tenderness. This occurs less frequently than orchitis in men and does not typically affect fertility.
Neurological Symptoms
Among unvaccinated people, up to 10% develop viral meningitis, an inflammation of the membranes surrounding the brain and spinal cord. Symptoms include severe headache, stiff neck, sensitivity to light, and drowsiness. Mumps-related meningitis is usually mild and resolves on its own. Encephalitis, actual inflammation of the brain itself, is much rarer and more serious, with symptoms like confusion, seizures, or extreme drowsiness.
Hearing loss occurs in up to 4% of unvaccinated mumps patients. It’s usually temporary, but in rare cases it can be permanent and typically affects only one ear.
Pancreas Inflammation
Pancreatitis develops in up to 4% of unvaccinated cases and causes upper abdominal pain, nausea, and vomiting. This complication is also generally temporary.
Symptoms in Vaccinated People
People who received the MMR vaccine can still catch mumps in outbreak settings, though their illness tends to be milder. In the post-vaccine era, rates of meningitis, encephalitis, pancreatitis, and hearing loss have all dropped to 1% or less among infected individuals. Vaccinated people may still develop parotid swelling, but it’s often less severe and resolves more quickly. Some vaccinated individuals experience only mild, nonspecific symptoms without any noticeable jaw swelling, which can make the infection harder to recognize.
How Mumps Is Diagnosed
Doctors often suspect mumps based on the distinctive jaw swelling alone, especially if there’s a known outbreak in the area. To confirm the diagnosis, a healthcare provider will typically swab the inside of your cheek or collect a blood sample. The most reliable confirmation comes from a PCR test that detects the virus’s genetic material in saliva, or from a blood test showing a significant rise in mumps-specific antibodies between two draws taken a couple of weeks apart. A single blood test for a specific type of antibody (IgM) can support the diagnosis but isn’t definitive on its own. Importantly, a negative test result doesn’t always rule mumps out, particularly if the sample is collected too early or too late in the illness.