Measles is a highly contagious viral infection that causes various cold-like symptoms and a characteristic rash. It can cause severe complications and may be fatal in some people. Vaccination is effective for prevention.
Measles is caused by a virus.
Symptoms include fever, runny nose, hacking cough, red eyes, and a red rash.
The diagnosis is usually based on typical symptoms, the characteristic rash or white spots in the throat.
Laboratory testing is done to confirm the diagnosis of measles in people who have consistent symptoms and in those with risk factors for measles exposure.
There is no antiviral medication for measles, so treatment is aimed at relieving symptoms.
Children with measles can be treated with vitamin A.Children with measles can be treated with vitamin A.
Although most people recover, measles can be fatal or lead to brain damage.
Routine vaccination prevents the infection.
Measles infections are uncommon in areas where most people have received the measles vaccine. Before measles vaccination became widely available, measles epidemics occurred every 2 or 3 years, particularly in preschool-aged and school-aged children. Small, local outbreaks occurred during the other years.
Measles is still common in some countries. Worldwide, each year, measles infects about 10 million people and causes about 100,000 deaths, mostly in children.
In the United States, measles is not common because of routine childhood vaccination. From 2000 to 2010, an average of only 71 cases per year were reported to the Centers for Disease Control and Prevention (CDC).
In 2019, 1,274 cases of measles were reported to the CDC. That was the highest number reported since 1992. The increase in 2019 was mostly caused by unvaccinated people who became infected in countries where measles is more common and then traveled to the United States. In 2020, only 13 measles cases were reported in the United States amid the COVID-19 global pandemic. From 2020 to 2023, there were 242 reported cases combined, and in 2024 there were 285 cases in the United States.
Both the total number of cases and the number of outbreaks have increased significantly in 2025. From January through May 22, 2025, 1,046 cases and 3 deaths were reported in the United States. There were 14 outbreaks and 92% of the cases have been associated with an outbreak. For comparison, 16 outbreaks were reported for the full year in 2024.
The number of outbreaks and overall measles cases is increasing because the vaccination rate is decreasing. Vaccine hesitancy has become a more frequent cause of the decrease in vaccination rates. Vaccine hesitancy is when parents delay or do not consent to their children being given some or all of the recommended vaccines. For example, the vaccination rate among kindergartners in the United States decreased from 95.2% in the 2019–2020 school year to 92.7% in the 2023–2024 school year.
Infographic courtesy of the Centers for Disease Control and Prevention (CDC).
Transmission of Measles
People typically become infected with measles by breathing in large or small airborne droplets of moisture coughed out by an infected person. People may become infected by touching surfaces the droplets land on, but this route of infection is much less common. Most people who are not immune to measles develop the infection after they are exposed to the virus.
Measles is contagious from 4 days before through 4 days after the rash appears. People who have measles may not realize they are infected or contagious and may unknowingly spread the infection to others.
Travel to areas where measles is common or to where an outbreak is active is a risk factor for measles transmission.
A pregnant woman who has had measles or has been vaccinated passes immunity to her child in the form of antibodies that cross the placenta. This immunity lasts for most of the first 6 to 12 months of life. Thereafter, however, children who are exposed to the measles virus are at high risk of becoming infected unless they have been vaccinated.
A person who has had measles develops immunity and typically cannot become infected with measles again. Adults born before 1957 are also presumed to have been exposed to measles and therefore be immune.
Symptoms of Measles
Measles is a contagious viral infection that usually develops in a typical time pattern (numbers of days are approximate and vary for each person):
Exposure: This is when a person comes into contact with the virus.
Incubation period: After exposure, it usually takes about 7 to 21 days (an average of 11 to 12 days) for symptoms to start. During this time, the virus is in the body, but the person does not feel sick.
Prodrome: This phase lasts about 3 to 7 days. Symptoms such as fever, cough, runny nose, and red eyes appear during this time, and small white spots may appear in the throat, but the rash has not yet developed.
Rash: The measles rash appears after the prodrome phase and lasts for about 4 to 7 days. It usually starts on the face and spreads to the rest of the body. After this period, the rash begins to fade quickly. If no complications develop, the person starts to feel better.
Measles symptoms begin about 11 to 12 days after a person is exposed to the virus. The infected person first develops a fever, runny nose, hacking cough, and red eyes.
Before the rash begins, Koplik spots may appear inside the mouth. Koplik spots are tiny, bright red spots with white or bluish white centers. The centers may resemble grains of sand.
Koplik spots are bright red spots with white or bluish white centers that may resemble grains of sand. They may occur anywhere in the mouth in people who have measles.
Images courtesy of the Public Health Image Library of the Centers for Disease Control and Prevention.
Koplik spots are bright red spots with white or bluish white centers that may resemble grains of sand. They may occur anywhere in the mouth in people who have measles.
DR P. MARAZZI/SCIENCE PHOTO LIBRARY
Koplik spots are bright red spots with white or bluish white centers that may resemble grains of sand. They may occur anywhere in the mouth in people who have measles.
DR P. MARAZZI/SCIENCE PHOTO LIBRARY
Koplik spots are bright red spots with white or bluish white centers that may resemble grains of sand. They may occur anywhere in the mouth in people who have measles.
Images courtesy of the Public Health Image Library of the Centers for Disease Control and Prevention.
Koplik spots are bright red spots with white or bluish white centers that may resemble grains of sand. They may occur anywhere in the mouth in people who have measles.
DR P. MARAZZI/SCIENCE PHOTO LIBRARY
Koplik spots are bright red spots with white or bluish white centers that may resemble grains of sand. They may occur anywhere in the mouth in people who have measles.
DR P. MARAZZI/SCIENCE PHOTO LIBRARY
A rash appears 3 to 7 days after the start of symptoms. The rash begins on the face in front of and below the ears and on the side of the neck. It looks like irregular, flat areas that soon become raised. The rash is red in people with light skin and can be purplish or darker than the surrounding area in people with dark skin. The rash spreads within 1 to 2 days to the trunk, arms, palms, legs, and soles and then begins to fade on the face. The skin may peel after the rash on the face fades.
This photo shows the rash caused by measles.
Image courtesy of the Public Health Image Library of the Centers for Disease Control and Prevention.
This photo shows the rash caused by measles.
SCIENCE PHOTO LIBRARY
This photo shows the rash caused by measles.
CDC/ Betty G. Partin
This photo shows the rash caused by measles.
Image courtesy of the Public Health Image Library of the Centers for Disease Control and Prevention.
This photo shows the rash caused by measles.
SCIENCE PHOTO LIBRARY
This photo shows the rash caused by measles.
CDC/ Betty G. Partin
When the infection is most severe, the person feels very sick and develops eye inflammation (conjunctivitis), swelling, and sensitivity to bright light; the rash is extensive; and the person's temperature may exceed 104° F (40° C).
In another 4 to 7 days, the temperature falls, the person begins to feel better, and any remaining rash quickly fades. The rash turns a brownish color, and then the skin peels.
Infected people are contagious from 4 days before through 4 days after the rash begins.
Complications of measles
Young children and people who are pregnant, malnourished, or who have a weakened immune system are at higher risk of developing complications resulting from measles. Measles infection can lead to immune suppression that lasts for months to years after recovering from measles and can predispose previously infected people to other infections.
Bacterial infections associated with measles, called superinfections, include pneumonia, bronchitis, and otitis media (middle ear infection).
Pneumonia caused by measles infection of the lungs occurs in about 6% of people. In fatal cases of measles in infants, pneumonia is often the cause of death.
Temporary liver inflammation (hepatitis) and diarrhea may occur during an infection.
Brain infection (see encephalitis) occurs in about 1 out of 1,000 children with measles. If encephalitis occurs, it often starts with a high fever, headache, seizures, and coma, usually 2 days to 2 weeks after the rash appears. The illness may be brief, with recovery in about 1 week, or it may last longer, resulting in brain damage or death.
Excessive bleeding may occur after the measles infection resolves because the person's blood platelet levels become low (thrombocytopenia). People usually have bruising of the skin and mild bleeding, but occasionally bleeding is severe.
Subacute sclerosing panencephalitis is a rare, fatal complication of measles. It causes brain damage and progressive brain deterioration. These symptoms can develop up to 7 to 10 years after a measles infection and are more common among people who were originally infected with measles as young children (less than 5 years old).
Diagnosis of Measles
A doctor's evaluation
Laboratory tests
Doctors suspect measles in people who have the typical cold-like symptoms, Koplik spots, and the characteristic rash.
Doctors confirm the diagnosis by taking blood, urine, nose, and throat specimens and sending them to a laboratory for testing. These tests are especially helpful for diagnosing people who have symptoms and who also are not vaccinated or are not completely vaccinated or who recently have been exposed to the measles virus.
Treatment of Measles
Vitamin A for children
Medications to reduce fever
Sometimes antibiotics if bacterial infection develops
There is no antiviral medication to treat measles.
Infected people who are hospitalized should be placed in special hospital rooms and isolated from others during their illness. Infected people who are not hospitalized should severely limit contact with others during their illness.
Doctors give vitamin A to all children with measles because Doctors give vitamin A to all children with measles becausevitamin A has been shown to reduce the number of deaths and serious infections resulting from measles in countries where vitamin A deficiency is common.
Acetaminophen or ibuprofen may be given to reduce fever.Acetaminophen or ibuprofen may be given to reduce fever.
Antibiotics may be given to people who develop other infections caused by bacteria, such as an ear infection.
Prognosis for Measles
In the United States, measles is fatal in about 1 to 3 of 1,000 infected people. Worldwide, measles is fatal in about 1 of 100 infected people.
People who are infected as infants, people with limited access to medical care, people with severe malnutrition and vitamin A deficiency, and people who develop pneumonia have higher rates of death from measles.
See also Complications of measles.
Prevention of Measles
MMR vaccine
Prevention before exposure
People already infected with measles in the past are immune. This includes all adults born before 1957, who are presumed to be immune to measles because they were likely exposed to the virus.
Two doses of measles vaccine are 96% effective at preventing measles. Measles vaccination is given as part of the combined measles-mumps-rubella (MMR) vaccine, which contains live but weakened measles, mumps, and rubella viruses. The MMR vaccine is one of the routine immunizations of childhood and is given to children in most nations with a robust health care infrastructure.
The 2-dose MMR vaccine schedule was introduced in 1989; therefore, adults born from 1957 to 1989 may have received only a single dose. For adults in this group, an additional 1 to 2 doses are recommended in those whose blood tests do not show that they are immune and who are at higher risk of infection (for example, college students, health care workers, international travelers, contacts of immunocompromised people, and those with HIV infection).
The MMR vaccine generally provides lasting immunity and has decreased cases of measles in the United States by 99%.
In some people, the vaccine causes mild fever and a rash, but people are not contagious. The MMR vaccine does not cause autism spectrum disorder (see Measles-Mumps-Rubella (MMR) Vaccine: Concerns About Autism Spectrum Disorder).
MMR is a live vaccine and is not given during pregnancy. It is also not given to certain people who have a severely weakened immune system or to people who have had a serious, life-threatening allergic reaction (such as an anaphylactic reaction) to a vaccine component or to a previous dose of the vaccine.
For more information about who should and who should not receive the MMR vaccine, see Dose of and Recommendations for MMR Vaccine. See also Side Effects of MMR Vaccine.
Preventive treatment after exposure
Children (and adults) who are exposed to measles and who do not have immunity may be given the MMR vaccine within 3 days of exposure and may then be protected. If the vaccine cannot be given within 3 days or the exposed person is not eligible to receive the vaccine, immune globulin is given immediately (within 6 days).
People who received immune globulin by injection into a muscle can be given the MMR vaccine 6 months later, and people who received immune globulin by injection into a vein can be given the MMR vaccine 8 months later.
