Skip to main content

Health condition · Clinically reviewed

Measles, the 3 Cs, Koplik spots - and why vaccination still matters.

A highly contagious infection that is entirely preventable. Here is what it looks like, how it spreads, and what to do if you suspect it.

Jump to treatment
A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against UKHSA, NICE and WHO sources you can see at the end.

  • 03

    Current for 2026

    Reflects UK outbreak guidance, notification duties and post-exposure prophylaxis advice.

Key facts

Measles at a glance.

The essentials, in plain English - what it is, how it spreads, and where it stands in the UK today.

  • What it is

    A highly contagious viral infection caused by the measles virus, a paramyxovirus spread through airborne droplets and aerosols.

  • UK picture

    The UK lost and later regained its measles elimination status - cases are rising again, largely tied to falling MMR uptake.

  • The prodrome

    Fever, cough, coryza and conjunctivitis - the "3 Cs" - plus Koplik spots inside the cheeks, days before the rash appears.

  • The rash

    Maculopapular, starting on the face and behind the ears before spreading downward, usually 3 to 5 days after the first symptoms.

  • Infectious window

    Contagious from 4 days before the rash appears to 4 days after - isolation during this window limits spread.

  • Prevention

    Two doses of MMR on the UK schedule prevent the vast majority of cases - catch-up vaccination is available at any age.

Why this guide matters

A preventable illness that is returning.

Measles is not a relic. Falling vaccination uptake has brought it back to UK communities, and knowing the pattern early changes what happens next.

  • Vaccination is the real answer

    Two MMR doses prevent almost all cases - catch-up vaccination is available at any age and takes minutes to arrange.

  • Koplik spots are the giveaway

    These small white spots inside the cheeks appear before the rash and are distinctive enough to guide an early diagnosis.

  • Complications drive the risk

    Most people recover fully, but pneumonia, encephalitis and rare delayed complications explain why measles is still taken seriously.

How the diagnosis is made

From first symptoms to a confirmed case.

The steps a UK GP, urgent care service or UKHSA team will normally follow, in order - so you know what to expect and why.

  1. 01

    Assessing

    Clinical assessment

    A history and exam looking for the 3 Cs and Koplik spots - often sufficient for diagnosis during a known outbreak.

  2. 02

    Assessing

    Rash timeline review

    The pattern and timing of the rash is checked against the prodrome to confirm a classic measles presentation.

  3. 03

    Confirming

    Oral fluid or saliva test

    A UKHSA-coordinated swab confirms the diagnosis without needing a blood sample - the usual first-line test.

  4. 04

    Confirming

    Serology (IgM)

    A blood test for measles-specific IgM antibodies when oral fluid testing is unavailable or the result is unclear.

  5. 05

    Confirming

    UKHSA notification

    Measles is a notifiable disease - suspected cases are reported immediately so public health action can begin.

  6. 06

    Managing

    Contact tracing

    UKHSA maps likely exposure, identifies vulnerable contacts and advises on exclusion from school, nursery or work.

  7. 07

    Managing

    Isolation advice

    Clear guidance on staying away from school, nursery, work and healthcare settings while infectious.

Typical timeline: a same-day assessment, with confirmation and public health follow-up within days.

Symptoms

What measles actually looks like.

The classic prodrome, the telltale Koplik spots, the spreading rash - and the features that mean it's time to seek help fast.

  • Fever

    Often high, sometimes above 40°C, and the first symptom to appear - usually a week or so after exposure.

  • Cough, coryza and conjunctivitis

    The "3 Cs" - a dry cough, a runny nose and red, watering eyes that develop alongside the fever.

  • Koplik spots

    Tiny white spots on the inside of the cheeks - pathognomonic for measles and appearing just before the rash.

  • The measles rash

    Maculopapular, starting on the face and behind the ears before spreading down the body over several days.

  • Diarrhoea

    A common accompanying symptom, particularly in younger children, that can add to the risk of dehydration.

  • Ear infection (otitis media)

    One of the most frequent complications - worth checking for if a child develops ear pain during or after illness.

  • Pneumonia

    The leading cause of measles-related death - watch for breathlessness, chest pain or a worsening cough.

  • Red flag - encephalitis or breathing difficulty

    Confusion, seizures, drowsiness or laboured breathing need urgent same-day medical assessment.

Treatment

How measles is managed in the UK.

Supportive care for most, prompt post-exposure options for those at risk, and hospital care reserved for genuine complications.

  • Supportive care

    Rest, fluids and antipyretics such as paracetamol or ibuprofen - the mainstay of treatment for most cases, since there is no specific antiviral.

  • Vitamin A

    Recommended by WHO for children in low-resource settings or with malnutrition, and considered for severe UK cases.

  • Hospital admission

    For pneumonia, encephalitis or severe dehydration - specialist paediatric or infectious diseases care, commissioned accordingly.

  • Post-exposure MMR vaccine

    Given within 72 hours of exposure to someone not already immune - can prevent or lessen the illness.

  • Human normal immunoglobulin

    Offered within 6 days of exposure to high-risk contacts - infants, pregnant women and the immunocompromised - who cannot have the vaccine.

  • Isolation

    Avoiding school, nursery, work and healthcare settings while infectious, following UKHSA guidance, to protect others.

  • MMR vaccination

    Two doses on the UK schedule remain the single most effective prevention - catch-up vaccination is available at any age.

  • UKHSA outbreak management

    Contact tracing and coordinated public health action to identify exposure and contain onward transmission.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and international public health standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP knows your history and can tell you which parts apply to you. If you suspect measles, get seen promptly and call ahead.

  • UKHSA. Measles: guidance, data and analysis.

  • NICE Clinical Knowledge Summaries. Measles.

  • World Health Organization. Measles vaccines: WHO position paper.

  • UKHSA. Post-exposure prophylaxis for measles.

Red flags

When measles needs urgent attention.

Most cases settle with rest and fluids at home. These are the situations that don't - and where urgent medical review is needed.

  • Pneumonia

    The leading cause of measles-related death - breathlessness, chest pain or a worsening cough need prompt assessment.

  • Encephalitis

    Rare but serious - confusion, seizures or drowsiness can signal brain inflammation and long-term neurological damage.

  • Subacute sclerosing panencephalitis

    A rare, fatal, delayed complication that can appear years after the original infection - any unusual neurological decline in a measles survivor deserves urgent review.

  • Signs of dehydration

    Reduced urination, sunken eyes or lethargy, especially alongside diarrhoea and vomiting, need prompt fluid assessment.

  • Pregnancy

    Infection during pregnancy raises the risk of miscarriage and preterm birth - specialist obstetric and infectious diseases input is needed.

  • Immunocompromised patients

    A weakened immune system raises the risk of severe or prolonged disease - lower the threshold for hospital assessment.

  • Infants too young for vaccination

    Babies under the age for their first MMR dose rely entirely on those around them being immunised - exposure needs an urgent call to a GP or UKHSA.

  • Immune amnesia

    Measles can temporarily wipe out existing immune memory, leaving patients more vulnerable to other infections for months afterward.

  • Rapid deterioration

    Any high, persistent fever with a worsening rash, breathing difficulty or reduced consciousness warrants same-day medical review.

Living with it

A week at home, done carefully.

Four things that make the biggest difference while you or your child recover - isolating properly, staying comfortable, watching for complications and closing the loop on vaccination.

A quiet reminder

Call ahead before you turn up.

Phoning your GP or A&E before you arrive lets them keep other patients safe while you're seen.

  1. 01 Isolate

    Stay away from others

    Avoid school, nursery, work and healthcare settings from 4 days before the rash to 4 days after it appears.

  2. 02 Comfort

    Rest and fluids

    Plenty of fluids, rest and paracetamol or ibuprofen for fever and discomfort - most people recover at home within 7 to 10 days.

  3. 03 Watch

    Know the complications to watch for

    Ear pain, breathlessness or confusion are reasons to seek same-day medical advice rather than wait it out.

  4. 04 Protect

    Check the household is vaccinated

    Once everyone has recovered, use the opportunity to catch up any missed MMR doses across the family.

Frequently asked

Everything we get asked about measles.

Quick answers on spread, Koplik spots, exposure and vaccination.

  • What is measles?

    A highly contagious viral infection caused by the measles virus, a paramyxovirus. It spreads through airborne droplets and typically causes fever, cough, conjunctivitis and a spreading rash, with complications ranging from ear infections to pneumonia and, rarely, encephalitis.

  • How does measles spread?

    By airborne transmission - coughing, sneezing and even breathing near an infected person can spread the virus, which can also linger in the air of a room for up to two hours after someone infectious has left it.

  • What are Koplik spots?

    Tiny white spots that appear on the inside of the cheeks a day or two before the rash. They are considered pathognomonic for measles, meaning their presence is highly specific to this infection.

  • Why is measles making a comeback in the UK?

    Largely because MMR vaccination uptake has fallen below the level needed for herd immunity in some communities. The UK lost its WHO measles elimination status as a result and has since regained it, but outbreaks continue to occur where uptake remains low.

  • What should I do if my child is exposed to measles?

    Contact your GP or NHS 111 promptly. If your child is not fully vaccinated, an MMR vaccine given within 72 hours of exposure, or immunoglobulin within 6 days for those who cannot have the vaccine, can prevent or reduce the severity of illness.

  • Can adults get measles?

    Yes - anyone who has not had two doses of MMR or previous confirmed infection can catch measles at any age. Catch-up vaccination is available on the NHS regardless of age, and is worth checking if you are unsure of your own vaccination history.

Related content

Keep reading.

Pulse Healthcare concierge

Send us your enquiry

A concierge service for UK private healthcare. We match you with the best vetted clinics and consultants in our network - they then contact you directly.

So we can match you to the right clinician close to you.

We reply to every enquiry within 24 hours (Mon–Fri). Confidential - your details are never shared outside our vetted consultant network.