Measles
A highly contagious respiratory viral illness that can cause pneumonia, brain inflammation, pregnancy complications, and death.
What causes Measles?
Measles is caused by measles virus. It spreads through the air when an infected person breathes, coughs, or sneezes, and virus can remain infectious in an indoor space for up to about two hours.
Symptoms and what to notice
High fever, cough, runny nose, red watery eyes, tiny white Koplik spots inside the mouth, and a red rash that usually begins on the face and spreads downward.
How long can it last?
Symptoms usually begin 7 to 14 days after infection. Rash often appears 3 to 5 days after the first symptoms and lasts several days. A person can spread measles from about four days before through four days after rash onset.
How serious is Measles?
Measles can cause ear infection, diarrhea, pneumonia, encephalitis, pregnancy complications, hospitalization, and death. Infants, pregnant people, adults, and people with weakened immunity face higher risk.
Treatment and management
There is no routine measles-specific antiviral. Care focuses on hydration, fever management, nutrition, monitoring for complications, and clinician-directed vitamin A for children with measles. Severe disease may require hospital care.
Vaccine: who and when?
Products: M-M-R II and PRIORIX are interchangeable MMR vaccines. ProQuad is an MMRV product for children ages 12 months through 12 years. Children routinely receive two doses at 12-15 months and 4-6 years; susceptible older people and travelers follow risk-based schedules.
Cost note: Patient cost varies by product, provider, insurance, location, and eligibility. Many recommended vaccines are covered in network without cost sharing, and qualifying children may use the Vaccines for Children program.
Trusted source
Patient cost varies by insurance, provider, location, and eligibility. Coverage and public-health access differ, so listed prices are examples rather than guaranteed patient prices. This page is for general education and does not replace individualized medical advice, diagnosis, vaccination assessment, or treatment.
Measles: Symptoms, Causes, Treatment, Prevention, and Vaccine Information
Measles is one of the most contagious human infections. It is not merely a childhood rash: the virus temporarily weakens immune defenses and can cause severe lung or neurologic disease. Because people spread measles before the rash makes the diagnosis obvious, one imported case can produce a large outbreak wherever vaccination coverage has fallen. Two appropriately timed MMR doses provide the best protection.
Important: This page is for general education. It does not replace diagnosis, treatment, vaccination advice, or emergency care from a qualified healthcare professional.
Quick Facts
| Topic | Current information |
|---|---|
| Cause | Measles is caused by measles virus. It spreads through the air when an infected person breathes, coughs, or sneezes, and virus can remain infectious in an indoor space for up to about two hours. |
| Main symptoms | High fever, cough, runny nose, red watery eyes, tiny white Koplik spots inside the mouth, and a red rash that usually begins on the face and spreads downward. |
| Typical course | Symptoms usually begin 7 to 14 days after infection. Rash often appears 3 to 5 days after the first symptoms and lasts several days. A person can spread measles from about four days before through four days after rash onset. |
| Treatment | There is no routine measles-specific antiviral. Care focuses on hydration, fever management, nutrition, monitoring for complications, and clinician-directed vitamin A for children with measles. Severe disease may require hospital care. |
| Vaccine status | Products: M-M-R II and PRIORIX are interchangeable MMR vaccines. ProQuad is an MMRV product for children ages 12 months through 12 years. Children routinely receive two doses at 12-15 months and 4-6 years; susceptible older people and travelers follow risk-based schedules. |
History and Public-Health Importance
Before measles vaccine became available in 1963, nearly every U.S. child acquired the infection and hundreds died in some years. High vaccination coverage eliminated continuous U.S. transmission in 2000, but international travel continues to introduce the virus. Outbreak control depends on rapid diagnosis, airborne isolation, contact tracing, and timely vaccination or immune globulin for eligible exposed people.
What Causes Measles?
Measles is caused by measles virus. It spreads through the air when an infected person breathes, coughs, or sneezes, and virus can remain infectious in an indoor space for up to about two hours.
Measles virus travels in fine respiratory particles and can infect people who enter a room after the sick person has left. About nine in ten susceptible close contacts become infected. A person is infectious before the characteristic rash, so suspected cases should call ahead before visiting a clinic to prevent exposing waiting rooms and healthcare workers.
Symptoms and Typical Course
High fever, cough, runny nose, red watery eyes, tiny white Koplik spots inside the mouth, and a red rash that usually begins on the face and spreads downward.
Fever, cough, coryza, and conjunctivitis usually precede the rash. Fever may spike as the rash spreads from the hairline and face to the trunk and limbs. Koplik spots can appear briefly inside the cheeks. Cough and fatigue may persist after the rash fades. Laboratory confirmation is important because other viral rashes can look similar.
Complications and Who Is at Higher Risk
Measles can cause ear infection, diarrhea, pneumonia, encephalitis, pregnancy complications, hospitalization, and death. Infants, pregnant people, adults, and people with weakened immunity face higher risk.
Pneumonia is the most common cause of measles-related death. Encephalitis can lead to seizures, hearing loss, or intellectual disability. A rare fatal brain disorder, subacute sclerosing panencephalitis, can appear years later. Malnutrition, vitamin A deficiency, pregnancy, infancy, adulthood, and immunosuppression increase danger.
How It Is Diagnosed
Public-health laboratories confirm measles with RT-PCR from a throat or nasopharyngeal swab and serology. Samples should be collected promptly and the health department notified immediately. Testing and exposure history are essential because the rash alone is not specific and false-positive antibody results can occur when disease prevalence is low.
Treatment and Recovery
There is no routine measles-specific antiviral. Care focuses on hydration, fever management, nutrition, monitoring for complications, and clinician-directed vitamin A for children with measles. Severe disease may require hospital care.
Supportive care includes fluids, oxygen when needed, and treatment of bacterial complications. CDC and pediatric guidance support vitamin A for children diagnosed with measles, given under medical supervision because excessive vitamin A is toxic. Ribavirin is not routine treatment. Airborne precautions are required in healthcare settings.
Vaccine Information
Products: M-M-R II and PRIORIX are interchangeable MMR vaccines. ProQuad is an MMRV product for children ages 12 months through 12 years. Children routinely receive two doses at 12-15 months and 4-6 years; susceptible older people and travelers follow risk-based schedules.
M-M-R II and PRIORIX are live attenuated MMR vaccines and are considered interchangeable. ProQuad adds varicella vaccine and is licensed only for children. Live MMR-containing vaccine is not given during pregnancy or severe immunosuppression. International travelers may need earlier dosing; an early infant dose does not replace the routine doses after the first birthday. Eligible exposed people may benefit from MMR within 72 hours or immune globulin within six days.
Prevention
Keep two-dose MMR coverage high, verify immunity before international travel, avoid exposure during outbreaks, and follow health-department isolation instructions. Suspected patients should telephone ahead before seeking in-person care. Vaccination protects the recipient and people who cannot safely receive live vaccine.
When to Seek Medical Care
Call urgently for breathing difficulty, dehydration, confusion, seizures, severe weakness, or a worsening fever. Anyone with fever and rash after travel or a known exposure should contact a clinician and public health before arriving at a facility.
Frequently Asked Questions
Can vaccinated people get measles?
Breakthrough infection is uncommon. Two MMR doses are about 97% effective, and vaccinated cases are often less severe.
Does MMR cause autism?
No. Large, well-designed studies have found no causal link between MMR vaccination and autism.
Can measles spread before the rash?
Yes. People are contagious for about four days before rash onset, which is one reason outbreaks spread quickly.
Are M-M-R II and PRIORIX interchangeable?
Yes. CDC considers the two U.S. MMR products interchangeable for recommended indications.
Key Takeaway
Measles is airborne, exceptionally contagious, and capable of severe complications. Two MMR doses, rapid isolation, and prompt public-health action are the central protections.
Medical, treatment, and vaccine information was reviewed against official U.S. public-health guidance available through September 2026.