How Long Does a Cold Last and When Is It Contagious?
Medically Reviewed by Dr. Pedro Yelamo Vera, MD
Licensed Physician No. 484814280 · Official Medical College of Bizkaia (Spain)Last reviewed: 29 October 2026
How long does a cold last? Usually 7 to 10 days, though a cough can linger. When you are most contagious, what helps and when to see a doctor.
You don't have to figure this out alone
Dr. Pedro Yelamo Vera is an independent, bilingual GP licensed in Spain. Book a 15-minute video consultation in English or Spanish for €50, with a private electronic prescription issued under Spanish law when clinically appropriate.
A cold builds up over two or three days and usually starts to ease within a week. Most people feel back to normal in one to two weeks. A cough can hang on for longer, especially in children. You are most contagious in the first two or three days, and you can pass it on a few days before you feel ill.
- How long does a cold last? Usually 7 to 10 days, though a cough can linger for two to three weeks.
- You spread it most in the first two or three days.
- Rest, fluids and paracetamol or ibuprofen ease symptoms. Antibiotics do not help a cold.
- See a doctor if you are no better after 10 days, or you get worse after starting to improve.
- A baby under three months with a temperature of 38°C or more needs to be checked straight away.
Dr. Pedro Yelamo Vera is a GP licensed in Spain (Colegiado No. 484814280).
For a medical emergency, call 112 or go to the nearest local emergency department. Do not wait for a video consultation or an online reply.
How long does a cold last, day by day?
Symptoms usually start two or three days after you catch the virus, sometimes up to a week.
- Days 1 to 3: a scratchy throat, sneezing and a runny nose. This is when you spread it most.
- Days 2 to 4: symptoms peak. Your nose may block and you may feel tired.
- Days 4 to 7: the mucus often gets thicker. It may turn yellow or green. Spanish paediatricians (AEP) say this is normal, not a sign of infection on its own.
- Days 7 to 10: most symptoms fade.
- Weeks 2 to 3: a cough can hang on, often for two to three weeks in children (AEP).
When is a cold most contagious?
You are most contagious in the first two or three days. MedlinePlus says a cold is usually not contagious after the first week. The NHS is more cautious: you can pass it on until all symptoms have gone. You can also spread it a few days before you feel ill.
Cold viruses spread through coughs, sneezes and hands. Wash your hands often, use tissues and do not share cups or towels. Stay at home if you have a high temperature or feel too unwell for normal activities.
Is it a cold, flu, COVID or allergies?
These are the usual differences, based on Mayo Clinic and NHS guidance.
| Cold | Flu | COVID-19 | Allergies | |
|---|---|---|---|---|
| How it starts | Slowly, over 2 to 3 days | Suddenly, within hours | 2 to 14 days after contact | When you meet the trigger |
| Fever | Rare in adults | Common | Sometimes | No |
| Aches and exhaustion | Mild, if any | Common, often severe | Sometimes | No |
| How long | 3 to 10 days, up to 2 weeks | Usually longer and more severe | Varies | Weeks, while the trigger lasts |
For flu, see our guide to flu symptoms and how long flu lasts. In Spain, flu is often called gripe and a cold is a resfriado or catarro.
Why do children get so many colds?
Their immune system is meeting these viruses for the first time. The AEP says an adult has one or two colds a year. A child has five or six, with a peak in the first years of nursery (guardería) or school.
- Colds last longer in young children. They may feed and sleep poorly.
- Saline nose drops (suero fisiológico) before feeds and sleep help babies breathe.
- Do not give honey under 12 months or aspirin under 16.
- The AEP says cough and cold remedies are not indicated in children and can be harmful.
What helps a cold get better?
There is no cure; your body clears the virus. These steps ease the symptoms:
- Rest and drink plenty of water.
- Paracetamol or ibuprofen ease aches and fever. Follow the leaflet, and do not add a cold remedy that also contains paracetamol.
- Saline spray or drops help a blocked nose.
- Honey can soothe a cough in adults and children over one.
- Decongestant nasal sprays are for brief use only; longer use can make a blocked nose worse.
Do antibiotics, vitamin C or zinc help a cold?
Antibiotics do not help. Colds are caused by viruses, and antibiotics only work on bacteria.
Vitamin C: a Cochrane review found that taking it daily does not prevent colds in most people. It made colds slightly shorter in regular users. Starting it once a cold had begun showed no clear effect.
Zinc: a newer Cochrane review found zinc may shorten a cold a little when taken at the start. The evidence is weak, and zinc caused more side effects such as a bad taste or an upset stomach.
A cold that is dragging on, or a child you are worried about?
You can book a video visit with a GP licensed in Spain, in English or Spanish. He checks for signs of an ear, sinus or chest infection and tells you if you need to be seen in person.
When should you see a doctor about a cold?
- You are no better after 10 days.
- You start to improve, then get worse again.
- A high temperature lasts more than three days (NHS; the CDC says four).
- You have ear pain, or pain over your cheeks or forehead.
- A cough lasts more than three weeks.
- You have a long-term condition or a weak immune system.
- Your child seems very unwell, very sleepy or very irritable.
- A baby under three months has a temperature of 38°C or more. Get them checked straight away.
- A baby has fewer wet nappies, no tears or a dry mouth. These are signs of dehydration: get them checked the same day.
When is a cold an emergency?
Call 112 or go to the nearest emergency department if:
- Someone is struggling to breathe or breathing very fast.
- The lips, tongue or face turn blue or grey.
- They are confused, very drowsy or hard to wake.
- They have sudden chest pain.
- A baby has had no wet nappy for 12 hours or more.
Talking it through with a doctor by video
Dr. Yelamo is a GP licensed in Spain. He sees adults, children and pregnant patients by video, every day from 07:30 to 20:30 (Spain time). In the visit he will:
- Ask how long you have been ill and how the symptoms have changed.
- Look at your throat on camera and ask about ear, sinus and chest symptoms.
- Check for warning signs that mean you need to be seen in person.
- Explain what will ease the symptoms, and which medicines suit you or your child.
He does not promise any test or prescription before the visit. Where clinically appropriate, following a genuine evaluation. Treatment and prescriptions are issued solely at the doctor's discretion based on evidence-based clinical guidelines.
A prescription is never guaranteed: it is issued only where clinically appropriate after a genuine evaluation, as a private electronic prescription under Spanish law. This service is for urgent, non-emergency care. In an emergency, call 112.
See how the Urgent Care video visit works. It lasts 15 minutes and costs €50.
This guide is general information. It does not replace a consultation with your doctor.
Frequently asked questions
How long does a cold last?
Most ease within 7 to 10 days. A cough can last two to three weeks, especially in children.
How many days is a cold contagious?
You are most contagious in the first two or three days. MedlinePlus says a cold is usually not contagious after the first week; the NHS says you can pass it on until all symptoms have gone.
Does green mucus mean I need antibiotics?
No. Thick yellow or green mucus is part of the normal course of a cold. See a doctor if it lasts more than 10 days or comes with face pain or fever.
When is a cold serious in a baby?
A baby under three months with a temperature of 38°C or more needs checking straight away. Call 112 if a baby struggles to breathe, turns blue or grey, or has had no wet nappy for 12 hours. Fewer wet nappies, no tears or a dry mouth need a check the same day.
Sources
- NHS: Common cold
- CDC: Preventing and managing the common cold
- Mayo Clinic: COVID-19, cold, allergies and the flu
- Cochrane: Vitamin C for preventing and treating the common cold
- Cochrane: Zinc for prevention and treatment of the common cold
Related guides
Medical Citations & Sources
This content is written and reviewed by a licensed physician with reference to the following official health authorities.
