| Quick Answer Measles usually starts with a high fever, cough, runny nose, and red, watery eyes, followed a few days later by a rash that spreads from the head down the body. It spreads through the air when an infected person coughs or sneezes, and it’s so contagious that up to 9 out of 10 unprotected people nearby will catch it. The best protection is the MMR vaccine. |
Recognizing early measles symptoms is crucial, as the infection usually starts with a high fever, cough, runny nose, and red, watery eyes, followed a few days later by a rash that spreads from the head down the body. It spreads through the air when an infected person coughs or sneezes, and it’s so contagious that up to 9 out of 10 unprotected people nearby will catch it. The best protection is the MMR vaccine.
This article will provide all the relevant information in simple to understand language with many sources included for further reading.
What Is Measles?
Measles is a highly contagious viral infection caused by the measles virus. The virus is transmitted through the nasal and throat passages. Prior to the introduction and widespread use of the measles vaccine, almost all children had contracted the disease at some stage of life. Nowadays, the majority of cases are imported from outside the country when an infected person who has not been vaccinated introduces the virus into a community where measles is no longer present.
Early Symptoms of Measles
Symptoms don’t show up right away. It usually takes 7 to 14 days after someone is exposed to the virus before the first signs appear. Early symptoms feel a lot like a bad cold or flu, which is part of why measles can spread before anyone realises what it is. The first signs typically include:
- A high fever, which can climb to 104°F (40°C) or higher
- A persistent cough
- A runny nose
- Red, watery, sore eyes (conjunctivitis)
A couple of days into the illness, tiny white spots — called Koplik spots — can appear inside the mouth, usually on the inside of the cheeks. Not everyone gets these, but when they do show up, they’re a strong clue that measles is the cause.
The Measles Rash: What to Watch For
The telltale rash of measles usually appears 3 to 5 days after the first symptoms appear. It begins as flat, red spots on the face, along the hairline, and spreads down the neck, trunk, and extremities, and then to the rest of the body. The fever often peaks as the rash spreads and may be as high as 104°F.
The rash lasts for about a week and then disappears in the same order it appeared. A call to the doctor is necessary if a child (or adult) has a fever, cough, and red eyes followed by a widespread rash of flat, red spots, as a visit to the waiting room may spread the disease to others.
How Does Measles Spread?
This is the most surprising part: measles is highly contagious, regardless of how far you are from an infected person. The virus spreads when an infected person coughs, sneezes, or even talks − the droplets from these actions contain the virus and can travel through the air. According to the CDC, these droplets can stay suspended in the air for up to two hours after an infected person leaves the room. This means that you can get measles by visiting the same place that an infected person was in, even if you don’t see them.
Furthermore, infected people can spread the virus before they show symptoms of the disease. You can get measles by being in the same room or within range of an infected person’s cough or sneeze for four days before and after the appearance of a rash on their skin. This is why measles can quickly spread among students at school or passengers at an airport, even if no one knows that they have the infection.
Moreover, measles is one of the most contagious infections known to science: if an unvaccinated or unprotected person is exposed to an infected person, there is a 9 out of 10 chance that they will contract the infection, as reported by the NHS.
Who’s Most at Risk?
Anyone who isn’t vaccinated or hasn’t already had measles is at risk, but some groups face a much higher chance of serious complications:
- Babies and children under 5 years old
- Pregnant women
- People with weakened immune systems
About 1 in 5 unvaccinated people in the U.S. who catch measles end up in hospital. Complications can include ear infections, diarrhoea, pneumonia, and, in rare cases, swelling of the brain (encephalitis), which can cause lasting damage or death.
How to Protect Yourself and Your Family
The good news is that measles is both highly preventable and treatable. The MMR (measles, mumps, and rubella) vaccine is 97% effective with two doses. For community immunity, or herd immunity, 95% of the population needs to be vaccinated, which is unfortunately not the case anymore as the vaccination rate for kindergarten has dropped from over 95% a few years ago to just over 93% recently, contributing to the rise in measles cases.
Simple steps that help:
- Make sure children get both MMR doses on schedule
- Check your own vaccination records if you’re unsure, especially before international travel
- Stay home and call your doctor first if you suspect measles, rather than showing up unannounced
- Avoid contact with anyone who has a fever and rash until measles is ruled out
Key Takeaways
- Early measles symptoms look like a bad cold: fever, cough, runny nose, red eyes
- The rash appears 3 to 5 days later, starting at the hairline and spreading downward
- Measles spreads through the air and can linger in a room for up to two hours
- Up to 9 in 10 unvaccinated people exposed to measles will catch it
- The MMR vaccine remains the most effective way to prevent infection
Frequently Asked Questions
How soon do measles symptoms appear after exposure?
Symptoms typically appear 7 to 14 days after exposure to the virus, starting with fever, cough, and red eyes before the rash develops.
Can you catch measles from someone who doesn’t have a rash yet?
Yes. A person with measles can spread the virus for about four days before their rash appears, which is one of the main reasons it spreads so fast.
Is measles more dangerous for children or adults?
Measles can be serious for anyone, but children under 5, pregnant women, and people with weakened immune systems face the highest risk of complications.
Does the measles rash itch?
The rash can feel dry or slightly itchy for some people, though the main discomfort with measles usually comes from the fever and general illness rather than the rash itself.
How long is someone with measles contagious?
A person is contagious from about four days before the rash appears until four days after it appears, so isolation during this window is important.
