Measles is a highly infectious viral illness. It can be very unpleasant and possibly lead to serious complications, including blindness and even death. However, it's now rare in the UK due to the effectiveness of the MMR vaccination.

Anyone can get measles if they haven't been vaccinated or had it before, although it's most common in children aged between one and four years old.

The measles virus is contained in the millions of tiny droplets that come out of the nose and mouth when an infected person coughs or sneezes.

The virus spreads very easily, and measles is caused by breathing in these droplets or by touching a surface that has been contaminated with the droplets and then placing your hands near your nose or mouth.

The initial symptoms of measles include:

• cold-like symptoms
• red eyes and sensitivity to light
• fever
• greyish white spots in the mouth and throat

After a few days a red-brown spotty rash will appear. It usually starts behind the ears, then spreads around the head and neck before spreading to the legs and the rest of the body.

Look at our childhood conditions slideshow to see what the measles rash looks like.

When to see your GP

Most childhood rashes are not measles, but see your GP if you notice the above symptoms and suspect it's measles. Measles is a notifiable disease, which means that any doctor who diagnoses the infection must inform the local health authority in order to identify the source of the infection and stop it spreading.

If you notice any additional symptoms while your child has measles, seek urgent medical attention.

Measles can be extremely unpleasant and can lead to complications such as meningitis and pneumonia. In very rare cases people have died from measles.

Read more about the complications of measles.

Treating measles

There's no specific treatment for measles and your immune system should fight off infection within a couple of weeks.

If your child has measles, there are several things you can do to help make them feel more comfortable, including:

• closing the curtains to help reduce light sensitivity
• using damp cotton wool to clean the eyes
• taking paracetamol or ibuprofen to relieve fever, aches and pains
• drinking plenty of water to avoid dehydration

In severe cases of measles, especially if there are complications, hospital treatment will be needed.

Read more about treating measles.

Although vaccinated children are unlikely to catch it, keep your child away from other children for at least five days after the rash has appeared.

Once you have fought off the measles infection, you develop immunity (resistance) to it.

MMR

The most effective way of preventing measles is the measles, mumps and rubella (MMR) vaccine.

The first MMR vaccination should be given when your child is around 13 months old. A booster is given before your child starts school.

If your child is younger than 13 months and you think they may have been exposed to the measles virus, see your GP immediately. The MMR may be given if they are over six months old, or they may be given antibodies for immediate protection if they are younger than six months old.

Measles and pregnancy

If you're planning to get pregnant and you have not had measles, arrange with your GP to have the MMR vaccine.

If you catch measles during pregnancy, it can be passed on to your baby, which can be very damaging or even fatal to your baby. Measles in pregnancy can cause miscarriage, premature labour or a baby with low birthweight. The MMR jab cannot be given during pregnancy.

Read about symptoms of measles and watch a video about a mother whose daughter had measles.

The initial symptoms of measles appear around 10 days after you get the measles infection and generally last for up to 14 days. The measles rash usually appears a few days afterwards.

The initial symptoms of measles include:

• cold-like symptoms, such as runny nose, watery eyes, swollen eyelids and sneezing
• red eyes and sensitivity to light
• a mild to severe temperature, which may peak at over 40.6C (105F) for several days, then fall but go up again when the rash appears
• tiny greyish-white spots (called Koplik's spots) in the mouth and throat
• tiredness, irritability and general lack of energy
• aches and pains
• poor appetite
• dry cough
• red-brown spotty rash (see below)

Rash

The measles rash appears two to four days after initial symptoms and lasts for up to eight days. The spots usually start behind the ears, spread around the head and neck, then spread to the legs and the rest of the body.

The spots are initially small but quickly get bigger and often join together. Similar-looking rashes may be mistaken for measles, but measles has a range of other symptoms too, not just a rash.

Look at our childhood conditions slideshow to see what the measles rash looks like.

Most childhood rashes are not measles, but see your GP without delay if:

• You suspect it is measles.
• Your symptoms worsen.
• Your temperature increases to above 38C (100.4F).
• Your temperature stays high after other symptoms have gone.
• There are signs of other related illnesses or complications of measles.

Diagnosing measles

Your GP will usually be able to diagnose measles from the combination of symptoms, such as the characteristic rash and the small spots inside the mouth.

A simple saliva or blood test can confirm the diagnosis and identify the rubeola virus.

Doctors have a duty to notify the local Health Protection Unit of all reported and suspected cases of measles. They will also notify the child's school if necessary.

Your child should not return to school until at least five days after the appearance of the rash.

Measles is caused by infection with the rubeola virus. This virus is contained in the millions of tiny droplets that come out of the nose and mouth when someone with measles coughs or sneezes.

You can catch measles by breathing in these droplets or, if the droplets have settled on a surface, by touching the surface and then placing your hands near your nose or mouth. The measles virus can survive on surfaces for a few hours.

Once inside your body, the virus multiplies in the back of your throat and lungs before spreading throughout your body, including your respiratory system and the skin.

Someone with measles is infectious for two to four days before the rash appears and for about five days after it appears.

Immunity

Anyone who has not had measles before and hasn't been vaccinated can be infected. However, cases of re-infection after you have had the virus are extremely rare because the body builds up immunity (resistance) to the virus.

Most people who are not immune from measles and are sharing a house with somebody who is infected will catch it.

Your GP will usually be able to diagnose measles from the combination of symptoms you may have, such as the characteristic rash and the small spots inside the mouth.

A simple blood or saliva test can confirm the diagnosis and identify the rubeola virus.

Doctors have a duty to notify the local Health Protection Unit of all reported and suspected cases of measles. They will also notify the child's school if necessary.

Your child should not return to school until at least five days after the appearance of the rash.

Read about treating measles.

Glossary

Blood test

During a blood test, a sample of blood is taken from a vein using a needle, so it can be examined in a laboratory.

There is no specific treatment for measles. Once the rash starts, you will need to rest and treat the symptoms until your immune system fights off the virus.

If there are no complications due to measles, the symptoms will usually disappear within 7-10 days.

If your child has measles, you may find the following advice useful for making them more comfortable:

• Use liquid baby paracetamol or ibuprofen to relieve fever, aches and pains. Do not give aspirin to children under the age of 16.
• Closing curtains or dimming lights can help reduce light sensitivity.
• Damp cotton wool can be used to clean away any crustiness around the eyes. Use one piece of cotton wool per wipe for each eye. Gently clean the eye from inner to outer lid.
• Cough medicines are of little help and should not be given to children under the age of six.
• Children over 12 months old may benefit from a teaspoon of lemon juice and two teaspoons of honey in a glass of warm water. Honey should not be given to babies under the age of 12 months.
• Placing a bowl of water in the room will make the atmosphere more humid, which can help to relieve a cough.
• Feverish small children rapidly lose water, which makes a cough worse. Children should drink regularly to prevent dehydration.

While antibiotics are of no use to treat the virus, they may be prescribed for any secondary bacterial infections that develop.

In severe cases of measles, particularly when there are more serious complications, hospital treatment may be required.

Vitamin A

Vitamin A supplements have been shown in some studies to help prevent some of the serious complications arising from a measles infection, although it is not clear how they help.

Supplements may be recommended for children under two years old with severe measles, or for children with vitamin A deficiency (although this is rare in the UK).

You may wish to ask your GP about whether your child would benefit from taking vitamin A supplements.

There are many complications that can develop due to measles, although some are much rarer than others.

Complications resulting from measles are more likely to develop in certain children, including:

• children with a weakened immune system, such as those with leukaemia or AIDS
• children with a poor diet
• children under the age of five

Complications are also more likely to develop in adults who are over the age of 20.

Common complications

Some of the common complications of measles are:

• diarrhoea 
• vomiting
• eye infection (conjunctivitis)
• inflammation of the voice box (laryngitis)

Inner ear infection and inflammation (otitis media), which often causes earache, may also be a complication of measles.

Fits that are caused by a fever (febrile seizures) are also possible complications of measles. However, the fits, although alarming, are not usually dangerous.

Less common complications

Less common complications of measles are:

• meningitis 
• pneumonia (lung infection), signs of which are fast, difficult breathing, chest pain and deteriorating condition
• hepatitis (liver infection)
• encephalitis (inflammation of the brain), which can be fatal, so watch for drowsiness, headache and vomiting
• low platelet count, known medically as thrombocytopenia, which affects the blood's ability to clot
• bronchitis and croup (infection of the airways), characterised by a hacking or barking cough
• squint, if the virus affects the nerves and muscles of the eye

Rare complications

In rare cases, measles can lead to the following conditions:

• serious eye disorders, such as an infection of the optic nerve (the nerve that transmits information from the eye to the brain), known as optic neuritis, which can lead to blindness
• heart and nervous system problems
• a serious brain complication known as subacute sclerosing panencephalitis (SSPE), which can sometimes occur several years after measles – however, although the condition is fatal, it is very rare, occurring in only 1 in every 100,000 cases of measles 

If you think that your child may have measles, keep them away from other children for at least five days after the rash has appeared.

Vaccinated children and anyone who has already had measles are extremely unlikely to catch measles.

MMR vaccination

The first dose of the measles, mumps and rubella (MMR) vaccine should ideally be given to babies who are between 12 to 13 months old.

Children are given a second dose (often known as the booster dose) before they start school, usually between the ages of three and five years old, although the second dose can be given three months after the first.

Between 5%-10% of children aren't fully immune after the first dose. The second dose provides increased protection, with less than 1% of children remaining at risk after having it.

If a child younger than 13 months old is exposed to the measles virus, the action taken to prevent them developing the disease will depend on whether they are under or over six months old.

Children aged 6-13 months old

A child aged between 6 and 13 months who is exposed to the measles virus will normally be given the MMR vaccination to protect them from developing measles.

However, if a child is given the vaccine before their first birthday, they should still be given two further doses as part of the childhood vaccination programme. These doses should be given at around 13 months of age and before the child begins school.

Children aged under 6 months

If the child's mother has had measles in the past, the child will usually be immune to the measles infection because the mother's protective antibodies will have been passed to the baby in the womb.

However, if the mother has not had measles, the child may be given an injection of human normal immunoglobulin (HNIG). HNIG is not a vaccine. It is a special concentration of antibodies that can give short-term but immediate protection against measles.