Measles

Measles is one of the most contagious diseases known to humans, capable of spreading rapidly through communities and causing serious, sometimes fatal, complications—but it can be prevented with a safe and effective vaccine.

Table of contents

• What is measles?
• Symptoms and signs
• How measles spreads
• Complications and risks
• Diagnosis
• Treatment
• Prevention through vaccination
• Global impact

Rubeola, 10-day measles, red measles

What is measles?

Measles is a highly contagious illness caused by a virus. It is an acute viral respiratory illness, meaning it develops suddenly and affects the breathing system^[1]. The virus spreads easily when an infected person breathes, coughs, or sneezes, settling on surfaces and remaining in the air^[2][3].

Measles can affect anyone but is most common in children^[3]. The virus infects the respiratory tract first and then spreads throughout the entire body^[3]. Before the introduction of measles vaccine in 1963 and widespread vaccination, major outbreaks occurred approximately every two to three years and caused an estimated 2.6 million deaths each year^[3].

Although measles was declared eliminated from the United States in 2000, cases still occur when unvaccinated travelers bring the virus from other countries^[4]. As of early 2025, the United States has experienced over 1,000 confirmed cases across 31 states, representing the highest rate of measles infections in decades^[5].

Symptoms and signs

Measles symptoms typically appear 7 to 14 days after a person is exposed to the virus^[2][4]. The symptoms do not appear all at once but develop in stages.

The first symptoms usually include a high fever that may spike to more than 104°F (40°C), along with a dry cough, runny nose, and red, watering eyes called conjunctivitis^[1][4]. These early symptoms are sometimes described as the three “C”s: cough, coryza (runny nose), and conjunctivitis^[1]. Other symptoms can include body aches, tiredness, sore throat, muscle pain, and headache^[9].

About 2 to 3 days after the first symptoms begin, tiny white spots with red bases may appear inside the mouth on the inner lining of the cheek. These are called Koplik spots and are a distinctive sign of measles^[1][2]. These spots often fade when the rash begins to appear.

About 3 to 5 days after symptoms first start, or roughly 14 days after exposure to the virus, a rash appears^[1][2]. The rash is made up of large, flat spots and small raised bumps. It usually starts on the face and behind the ears, then spreads downward to the neck, chest, back, arms, legs, and feet^[1][2]. On lighter skin, the rash appears red. On darker skin, it may appear purple or darker than the surrounding skin, or it might be difficult to see^[9]. The spots may blend together as they spread^[9]. The rash typically does not itch^[9].

A person with measles can spread the virus to others from about 4 days before the rash appears until about 4 days after the rash develops^[1][4]. This means people are contagious even before they know they have measles. Sometimes people with weakened immune systems do not develop the rash at all^[1].

How measles spreads

Measles is extremely contagious. If one person in a room of unvaccinated people has measles, estimates suggest that 9 out of 10 people in the room will become infected^[4][9]. This makes measles one of the most contagious viruses known to humans^[5].

The virus spreads through respiratory droplets that are released into the air when an infected person breathes, coughs, sneezes, or talks^[9]. You can get measles just by being in a room where a person with measles has been, even up to 2 hours after that person has left^[4][6]. The airborne droplets can remain in a room for hours^[9].

Measles can also spread when droplets land on surfaces you touch, and you then touch your mouth, nose, or eyes^[9]. The virus can also be transmitted from a pregnant woman to her fetus or baby during pregnancy, delivery, or while breastfeeding^[9].

Complications and risks

Measles can cause serious health complications, especially in certain groups of people. Some people mistakenly think of measles as just a rash and fever that clear up in a few days, but measles can lead to severe illness requiring hospitalization^[1][4].

Common complications from measles include ear infections, diarrhea, bronchitis, and pneumonia (lung infection)^[1][4]. Pneumonia is the most common complication and occurs in about 1 in 20 cases; it is also the leading cause of measles-related death in young children^[5]. Measles infection can also be complicated by secondary bacterial infections, which can cause tonsillitis, ear infections, and pneumonia^[1].

More serious complications can include brain swelling called encephalitis, which occurs in about 1 out of every 1,000 measles cases and often results in permanent brain damage^[1][4]. Encephalitis can cause seizures, hearing loss, or intellectual disability. Measles can also cause eye damage and occasionally blindness.

Between 1 and 3 out of every 1,000 children who become infected with measles will die from respiratory and neurologic complications^[1][3]. In recent outbreaks in the United States, including one in west Texas, unvaccinated school-age children have died from measles complications^[5].

Subacute sclerosing panencephalitis (SSPE) is a rare but fatal degenerative disease of the central nervous system that can develop 7 to 10 years after measles infection^[1]. This condition is characterized by behavioral and intellectual deterioration, seizures, coma, and death^[5].

Measles causes a unique phenomenon called immune amnesia, which means the virus “resets” a person’s immune system by erasing its memory of other pathogens^[5]. After recovering from measles, a person will have high immunity to measles but low or no immunity to other diseases for 2 to 3 years. This effect makes people more vulnerable to other infections and can render previous vaccinations ineffective during that period.

People at highest risk for severe complications include infants and children younger than 5 years old, adults older than 20 years, pregnant women, and people with weakened immune systems from conditions such as leukemia or HIV infection^[1][9].

Measles during pregnancy can result in serious outcomes for both the pregnant woman and the baby. Women may develop pneumonia or even die from measles^[1]. Measles can also lead to pregnancy loss, premature delivery, and low birth weight. If measles is transmitted to a fetus during pregnancy, the newborn can develop congenital measles infection, which appears as a fever and rash within 10 days of birth^[1]. Congenital measles can result in severe complications, including encephalitis and death, and carries a higher risk of developing SSPE later in life.

Diagnosis

If you suspect you or your child has been infected with measles, it is important to see a healthcare provider right away^[5]. However, you should call ahead before visiting a doctor’s office or emergency room to avoid exposing others to the virus.

Measles may be diagnosed by a healthcare professional based on the distinctive rash and the presence of Koplik spots inside the mouth^[2][8]. The healthcare provider may ask about vaccination history, recent travel to areas where measles is spreading, or contact with anyone who had a rash or fever^[2].

Laboratory tests can confirm that a person has measles^[2][5]. Laboratory confirmation is essential for all suspected measles cases and all outbreaks^[1]. To test for measles, a healthcare professional may use a swab to collect a sample from the nose or throat. Blood or urine samples may also be collected^[2][8]. These tests may look for genetic evidence of the virus or proteins used in the body’s immune response to the virus.

Measles is a reportable disease in most nations, including the United States^[6]. Healthcare providers are required to report suspected measles cases to their local health department^[1].

Treatment

There is no specific antiviral medication or cure for measles^[2][8][9]. The virus has to run its course. Treatment focuses on managing symptoms, preventing complications, and supporting the comfort and hydration of an infected person^[7][11].

Supportive care includes getting plenty of rest, drinking lots of fluids to prevent dehydration, and staying home from school, daycare, and other community activities to prevent spreading the infection^[7][12]. For fever and discomfort, medicines available without a prescription such as acetaminophen or ibuprofen may help^[8][11]. Aspirin should never be given to children or teens with viral illnesses, as it is linked to Reye syndrome, a life-threatening condition^[12].

If dehydration becomes severe, intravenous fluids may be necessary^[11]. If bacterial infections develop, such as ear infections or pneumonia, antibiotics may be prescribed^[5][11]. Patients hospitalized with breathing difficulties may receive oxygen support^[5].

Vitamin A supplementation is recommended for children diagnosed with measles, especially those who are malnourished or show clinical signs of vitamin A deficiency^[8][11]. Vitamin A supplements have been associated with reductions of approximately 50% in illness and death from measles and can help prevent eye damage and blindness^[11]. However, large amounts of vitamin A can have toxic effects on the liver, so it must be given under a doctor’s supervision^[5]. Vitamin A does not prevent measles and is not a substitute for vaccination^[5].

The World Health Organization recommends that all children diagnosed with measles should receive vitamin A supplementation based on their age: infants younger than 6 months receive 50,000 IU per day for 2 doses; those age 6-11 months receive 100,000 IU per day for 2 doses; and children older than 1 year receive 200,000 IU per day for 2 doses^[11].

For people exposed to measles who are not immune, preventive measures may be available. If given within 72 hours of exposure, the measles vaccine may prevent or reduce the severity of the disease^[7][11]. Children up to 11 months old who are exposed to measles and are not immune can receive a shot of immune globulin within 6 days of exposure^[8]. This shot contains proteins called antibodies that help the body clear an infection. Providing immune globulin to newborns may prevent or reduce the severity of congenital measles and reduce the risk of death^[1].

Patients with measles should be isolated for 4 days after they develop a rash, and airborne precautions should be followed in healthcare settings^[1]. Susceptible healthcare workers should be excused from work from the fifth to the 21st day after exposure^[11].

Prevention through vaccination

The best protection against measles is vaccination with the measles, mumps, and rubella (MMR) vaccine^[1][3][4]. The vaccine is safe and helps your body fight off the virus. Two doses of MMR vaccine are about 97% effective at preventing measles, while one dose is about 93% effective^[4].

The first dose of MMR vaccine is typically given to children at age 12 to 15 months, followed by a second dose between age 4 and 6 years^[7][9]. Infants younger than 12 months are generally too young to receive the vaccine, though they may have some protection from antibodies passed from their vaccinated mother during pregnancy^[19]. This protection wanes by about 6 months of age.

For most adults born during or after 1957, one dose of measles vaccine is sufficient to be considered protected from measles^[15]. However, certain groups of adults are recommended to have 2 lifetime documented doses separated by at least 28 days. These include students at post-high school educational institutions, healthcare personnel, international travelers, and people determined by public health authorities to be at increased risk during a measles outbreak^[15].

People born before 1957 are generally considered immune because they likely had measles disease as children and developed life-long immunity^[19]. If you are unsure whether you are immune to measles, you should try to find your vaccination records or check with your healthcare provider^[15]. If you do not have written documentation of measles immunity, you should get vaccinated with the MMR vaccine. There is no harm in getting another dose of MMR vaccine if you may already be immune to measles^[15].

In areas where measles outbreaks are occurring, additional or early vaccination may be recommended^[18]. For example, health departments may recommend a second dose for children age 1 to 4 years who received one dose and live in or plan to travel to the outbreak area. An early dose may be recommended for infants age 6 through 11 months living in or traveling to outbreak areas.

If you are planning international travel, it is important to ensure that you and your family are protected against measles^[15]. Talk to your healthcare provider about what vaccines you may need before your trip.

People who should not receive the measles vaccine include those who are immunocompromised or pregnant, or those who have had an allergic reaction to a previous vaccine dose, which is very rare^[19]. If you received 2 doses of measles vaccine at age 12 months or older according to the vaccination schedule, you should be protected for life and do not need a booster dose^[15].

Global impact

Before the introduction of measles vaccine in 1963 and widespread vaccination, major epidemics occurred approximately every two to three years and caused an estimated 2.6 million deaths each year worldwide^[3]. In the United States alone, before an effective vaccine was developed, nearly every child got measles, and 400 to 500 people died each year^[17].

Measles vaccination has averted more than 60 million deaths between 2000 and 2023^[3]. Accelerated immunization activities by countries, WHO, and other international partners successfully reduced estimated measles deaths from 800,062 in 2000 to 107,500 in 2023^[3].

Despite the availability of a safe and cost-effective vaccine, an estimated 107,500 people died from measles in 2023, mostly children under the age of 5 years^[3]. The proportion of children receiving a first dose of measles vaccine was 83% in 2023, well below the 2019 level of 86%^[3]. Experts estimate that when 95% of people in a community are vaccinated, both those individuals and others in their community are protected against measles^[5].

The COVID-19 pandemic led to setbacks in surveillance and immunization efforts^[3]. The suspension of immunization services and declines in immunization rates across the globe left millions of children vulnerable to preventable diseases like measles. No country is exempt from measles, and areas with low immunization encourage the virus to circulate, increasing the likelihood of outbreaks and putting all unvaccinated children at risk^[3].

Measles is still common in many parts of the world, particularly in Africa and Southeast Asia^[3][6]. Every year, measles is brought into the United States by unvaccinated travelers who get measles while they are in other countries^[4]. These travelers can then introduce measles to their communities upon their return, particularly affecting unvaccinated groups of children.

Choosing not to vaccinate children not only leaves them susceptible to measles, but also exposes other children to the disease, including infants who are too young to be vaccinated^[18]. Declining vaccination rates in many parts of the United States mean that more unvaccinated children, teens, and adults live in our communities, making outbreaks more likely.