Measles is a viral infection that spreads through the air and causes fever, rash, and cough

Measles is caused by a virus that travels through coughing and sneezing. When someone with measles breathes out, tiny droplets carrying the virus float through the air. If you breathe in those droplets, you can catch it. The infection starts in your lungs and spreads through your body, triggering a fever, a distinctive rash, and other symptoms that usually appear 10 to 14 days after exposure.

Measles is highly contagious — if you are not protected by vaccination or past infection, your chances of catching it from an infected person are very high. Before the measles vaccine became widespread in the 1960s, nearly every child caught measles. Today it is rare in countries with high vaccination rates, but it still spreads quickly in communities where vaccination rates are lower.

Key Takeaways

  • Measles starts with fever, cough, and runny nose, followed by a rash that appears on the face and spreads downward over three to four days.
  • The virus spreads through the air when an infected person coughs or sneezes, and people are contagious from four days before the rash appears until four days after it starts.
  • A doctor can diagnose measles by examining the rash and checking for small white spots inside the mouth, or by ordering a blood test to confirm the virus.
  • Most people recover on their own within one to two weeks, but measles can cause serious complications like pneumonia, brain inflammation, and ear infections.
  • The MMR vaccine prevents measles and is given to children starting at 12 months old, with a second dose at 4 to 6 years old.

The symptoms appear in two stages: cold-like illness, then rash

Measles begins like a common cold. You develop a fever, cough, runny nose, and sore throat. Your eyes may feel irritated and watery. These symptoms last two to three days, and you might feel tired and achy. During this stage, you are contagious but the rash has not yet appeared, so people may not realize you have measles.

Around day three or four, the fever usually drops briefly, then spikes again. This is when the rash appears. It starts as small, flat red spots on your face near the hairline and behind your ears. Over the next three to four days, the rash spreads down your neck, across your chest, and down your arms and legs. The spots may merge together in some areas. At the same time, you may notice small white spots with red halos inside your mouth — these are called Koplik spots and are a hallmark sign of measles.

The rash is itchy but does not usually blister or leave scars. As the rash fades, it may turn brown and flake slightly. Most people feel sickest when the rash first appears, then gradually improve over the next week.

How doctors recognize and confirm measles

A doctor can often diagnose measles by looking at the rash and asking about your symptoms. The combination of fever, cough, and a rash that starts on the face and spreads downward is distinctive. Koplik spots inside the mouth are especially helpful because they appear before the main rash and are rarely seen with other illnesses.

If the diagnosis is unclear, your doctor can order a blood test to look for measles antibodies — proteins your immune system makes to fight the virus. The test can confirm measles even before the rash fully develops. Some doctors also test a sample from your nose or throat to detect the virus directly.

Timing matters for testing. Antibodies may not show up in blood tests during the first few days of illness, so your doctor may recommend waiting a few days and testing again if the initial test is negative but measles is still suspected.

Measles can lead to serious complications, especially in young children and adults

Most people recover from measles without lasting problems, but the infection can trigger complications. The most common is pneumonia — an infection in the lungs that makes breathing difficult. Pneumonia can develop during measles or in the weeks after the rash fades.

Other complications include ear infections, which can cause hearing loss; encephalitis, an inflammation of the brain that can cause seizures and brain damage; and subacute sclerosing panencephalitis (SSPE), a rare but serious brain disease that can develop years after measles infection. Measles also temporarily weakens your immune system, making you more vulnerable to other infections.

Babies under one year old, adults over 20, pregnant women, and people with weakened immune systems face higher risk of complications. People who are malnourished or lack vitamin A are also at greater risk. In rare cases, measles can be fatal, particularly in infants and people with compromised immunity.

Treatment focuses on managing symptoms while your body fights the virus

There is no medicine that kills the measles virus. Treatment means managing fever and discomfort while your immune system clears the infection. Over-the-counter fever reducers like acetaminophen or ibuprofen can lower fever and ease aches. Drinking plenty of fluids helps prevent dehydration.

Rest is important — your body needs energy to fight the infection. Most people feel well enough to return to normal activities within one to two weeks after the rash appears, though some fatigue may linger.

If complications develop — such as difficulty breathing, severe headache, or confusion — seek medical care immediately. Hospitalization may be needed for severe pneumonia, encephalitis, or other serious complications. Vitamin A supplements are sometimes given to children with measles, especially those at risk for complications, because vitamin A supports immune function.

When to contact a doctor

Contact your doctor if you develop fever, cough, and rash, especially if the rash starts on your face and spreads downward. This is particularly important if you have been around someone with measles or if you are unsure whether you have been vaccinated.

Seek immediate medical attention if you develop difficulty breathing, chest pain, severe headache, confusion, stiff neck, or seizures. These can signal pneumonia, encephalitis, or other serious complications. If you are pregnant, have a weakened immune system, or are caring for an infant, call your doctor as soon as symptoms appear rather than waiting to see if they improve on their own.

Vaccination prevents measles and is part of routine childhood care

The MMR vaccine protects against measles, mumps, and rubella. It is given as a shot, usually at 12 to 15 months of age, with a second dose at 4 to 6 years old. Two doses provide lifelong protection for most people.

The vaccine is very effective — about 97 percent of people who receive both doses are protected. If you were vaccinated as a child but are unsure whether you received both doses, your doctor can check your vaccination record or order a blood test to confirm immunity.

Adults born in 1957 or later who have not been vaccinated or whose vaccination status is unknown should talk to their doctor about getting the vaccine. The vaccine is not given during pregnancy, but it is safe for breastfeeding mothers. People with certain medical conditions or weakened immune systems may not be able to receive the live vaccine, so discuss your health history with your doctor.

Frequently Asked Questions

Can you catch measles twice?

No. Once you recover from measles, your immune system produces antibodies that protect you for life. You cannot catch measles again. Vaccination provides the same lifelong protection without the illness.

How long are you contagious with measles?

You are contagious from four days before the rash appears until four days after it starts. This means you can spread measles to others before you even know you have it. Stay home and avoid contact with others during this time, especially unvaccinated people and those at high risk of complications.

Is measles the same as German measles?

No. Measles and German measles (rubella) are caused by different viruses and produce different rashes. German measles causes a milder illness with a smaller, lighter rash. The MMR vaccine protects against both.

What should I do if I think I have been exposed to measles?

Contact your doctor right away. If you are unvaccinated or unsure of your vaccination status, your doctor may recommend the vaccine within 72 hours of exposure, which can prevent infection or reduce severity. If you are already showing symptoms, the vaccine will not help, but your doctor needs to know so you can be monitored for complications.

Can adults get measles?

Yes. Adults who were not vaccinated or did not have measles as a child can catch it. Measles tends to be more severe in adults than in children, with higher rates of pneumonia and other complications. This is another reason vaccination is important for all age groups.