There are several problems that often occur with mumps. These can be worrying, but they are rarely serious and usually improve as the infection passes.

Common complications

Swollen testicle

Pain and swelling of the testicles (orchitis) affects one in four males who get mumps after puberty. The swelling is usually sudden and affects only one testicle. The testicle may also feel warm and tender.

In affected boys and men swelling of their testicles normally begins four to eight days after the swelling of the parotid gland. Occasionally, swelling can occur up to six weeks after the swelling of the glands.

Any testicle pain can be eased using over-the-counter painkillers, such as paracetamol or ibuprofen. If the pain is particularly severe, contact your GP who may prescribe a stronger painkiller for you.

Applying cold or warm compresses to your testicles and wearing supportive underwear, may also reduce any pain.

Just under half of all males who get mumps-related orchitis will notice some shrinkage of their testicles and an estimated 1 in 10 men will experience a drop in their sperm count (the amount of healthy sperm that their body can produce). However, this is very rarely large enough to cause infertility.

Swollen ovaries

One in 20 females who get mumps after puberty will experience swelling of the ovaries (oophoritis), which can cause:

• lower abdominal pain
• high temperature
• being sick

The symptoms of oophoritis usually pass once the body has fought off the underlying mumps infection.

Viral meningitis

Viral meningitis can occur if the mumps virus spreads into the outer protective layer of the brain, which is known as the meninges. It occurs in about one in seven cases of mumps.

Unlike bacterial meningitis, which is regarded as a potentially life-threatening medical emergency, viral meningitis causes milder, flu-like symptoms, and the risk of serious complications is low.

Sensitivity to light and vomiting are common symptoms of viral meningitis. These usually pass within 14 days.

Pancreatitis

About 1 in 20 cases of mumps leads to the short-term inflammation of the pancreas (acute pancreatitis). The most common symptom is sudden pain in the centre of your belly. Other symptoms of acute pancreatitis can include:

• feeling sick
• being sick
• diarrhoea
• loss of appetite
• high temperature
• tenderness of the belly
• (less commonly) yellowing of the skin and the whites of the eyes (jaundice)

Although the pancreatitis associated with mumps is usually mild, you may be admitted to hospital so your body functions can be supported until your pancreas recovers.

Rare complications of mumps

Rare but potentially serious complications of mumps include an infection of the brain itself, which is known as encephalitis. This is thought to occur in around 1 in 1,000 people who develop viral meningitis due to mumps. Encephalitis is a potentially fatal condition that requires admission to a hospital intensive care unit.
 
About 1 in 20 people with mumps will experience some temporary hearing loss, but permanent loss of hearing is rare. It is estimated this occurs in around 1 in 20,000 cases of mumps.