Flu Symptoms: How Long Flu Lasts and When to Worry

Flu usually lasts about a week. Fever, aches and exhaustion are worst in the first two to three days. Most people recover within a few days to less than two weeks, but a cough and tiredness can linger longer. You are most contagious in the first three days. Trouble breathing or chest pain: call 112.

What are the symptoms of flu?

Flu symptoms usually start suddenly. You can feel fine in the morning and be in bed by the evening. The NHS and the CDC list:

• A high temperature, often with chills.
• Aching muscles and body.
• Feeling exhausted or needing to lie down.
• A dry cough and a sore throat.
• Headache.
• Loss of appetite and trouble sleeping.
• A blocked or runny nose.
• Tummy pain, diarrhoea or vomiting, which are more common in children.

Not everyone with flu gets a fever.

How long does flu last?

Most people feel better within about a week, says the NHS. The CDC puts full recovery at a few days to less than two weeks. Fever and aches usually peak early. A cough and tiredness are often the last to go.

• Days 1–3: sudden fever, aches, exhaustion and headache. This is usually the worst part.
• Days 4–7: fever settles. Cough, sore throat and a blocked nose may take over.
• Week 2 and beyond: a lingering cough and low energy are common. You should be getting steadily better.

Feeling worse after you had started to improve is not normal recovery. A fever or cough that comes back can mean a complication such as a chest infection. Get checked.

How long is flu contagious?

You can pass flu on from about one day before symptoms start until five to seven days after, according to the CDC. You are most contagious in the first three days. Young children and people with a weak immune system may spread it for longer.

Flu spreads mainly through droplets when people cough, sneeze or talk. It can also spread from hands and surfaces. The NHS advises staying off work or school while you have a high temperature or do not feel well enough for normal activities. Wash your hands often and cough into a tissue or your elbow.

How soon do symptoms start after you catch flu?

Usually about two days after contact with the virus, with a range of one to four days. This is the incubation period. You can already spread flu on the last day before you feel ill.

What is "gripe A" in Spain?

"Gripe A" is the Spanish name for influenza A, one of the main types of seasonal flu. It is not a separate or more dangerous illness. Common subtypes include H1N1 and H3N2. Influenza B also circulates. The ECDC explains how these types spread across Europe each season.

In Spain, flu usually peaks in winter. The symptoms, care and warning signs are the same for type A and type B.

Is it flu, a cold or COVID?

A cold builds up slowly and mainly affects the nose and throat. Flu hits fast, with fever, aches and exhaustion that can put you in bed. You can still function with most colds. With flu, many people cannot.

COVID-19 and flu can look very alike: fever, cough, aches and tiredness. Only a test can tell them apart. The warning signs below apply to both.

What helps flu get better?

Most healthy people recover at home with simple care. The NHS advises:

• Rest and sleep.
• Keep warm.
• Drink plenty of fluids. Your pee should be pale.
• Take paracetamol or ibuprofen to bring down a fever and ease aches. Follow the leaflet.

Antibiotics do not work against flu, because flu is a virus. They are only used if a bacterial complication, such as pneumonia, develops. Many cold and flu remedies already contain paracetamol, so check the label to avoid taking a double amount.

Paracetamol or ibuprofen for flu?

Either can ease fever and aches. Paracetamol suits most people. Ibuprofen is not suitable for everyone: check with a pharmacist if you have stomach ulcers, kidney or heart problems, asthma made worse by painkillers, or you are pregnant. Follow the leaflet for how much and how often.

Never give aspirin to anyone under 16. The NHS warns it can cause Reye's syndrome, a rare but serious illness.

Who needs antiviral medicine for flu?

Antiviral medicine is mainly for people at higher risk of complications or who are very unwell. In Spain the most common one, oseltamivir (Tamiflu), needs a prescription. The CDC says antivirals work best when started within two days of the first symptoms.

The CDC lists these higher-risk groups:

• People aged 65 or over.
• Pregnant women.
• Young children.
• People with long-term heart, lung or kidney disease, or diabetes.
• People with a weak immune system.

For otherwise healthy adults the benefit is modest. A 2014 Cochrane review found oseltamivir shortened symptoms by less than a day on average. Whether it is right for you is a medical decision. A prescription is never automatic.

Can you get a flu jab if you have a cold?

Yes, a mild cold is not normally a reason to put off the flu vaccine. A fever is different. If you have a fever on the day, ask the nurse whether to wait.

Spain runs a flu vaccine campaign every autumn for higher-risk groups. Dates and eligible groups are set each season by the Ministry of Health and the regions. Our guide on the flu jab in Spain: who is eligible and where explains how to get one.

When should you call 112?

Call 112 or go to the nearest emergency department (urgencias) if an adult has any of these CDC emergency warning signs:

• Difficulty breathing or shortness of breath.
• Pain or pressure in the chest or tummy that does not go away.
• Dizziness or confusion that does not go away, or being hard to wake.
• Seizures.
• Not passing urine.
• Severe muscle pain or severe weakness.
• Fever or cough that improve, then come back or get worse.
• A long-term condition that is getting worse.

In children, also get help straight away for:

• Fast breathing or trouble breathing.
• Bluish lips or face.
• Ribs pulling in with each breath.
• Not waking up or not interacting.
• Fever with a rash.
• Signs of dehydration, such as no urine for many hours, no tears when crying or a dry mouth.

See our guide to emergency numbers in Spain.

When does a video visit help with flu?

A video visit helps when you are unsure what you have, are in a higher-risk group, or are not improving as expected. The doctor can check your symptoms and how long you have had them. They also look at your risk factors and medicines.

They can then advise on care at home and whether antivirals are worth considering. They will tell you plainly if you need to be seen in person. The visit costs €50, lasts 15 minutes and includes a medical report. It is available every day, 07:30–20:30 (Spain time), for adults, children and pregnant women. Treatment and prescriptions are issued solely at the doctor's discretion, where clinically appropriate, following a genuine evaluation.

Getting a medical assessment

If you have flu symptoms and none of the warning signs above, you can book a video visit with Dr. Pedro Yelamo Vera, a GP licensed in Spain (Colegiado No. 484814280), in English or Spanish. You can also read more on our flu treatment page. 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.

Frequently asked questions

Sources

• NHS: Flu
• CDC: Signs and symptoms of flu
• CDC: How flu spreads
• CDC: Treating flu with antiviral drugs
• ECDC: Factsheet about seasonal influenza
• Ministerio de Sanidad: Vacunaciones

This guide is general information. It does not replace the package leaflet or the advice of your doctor or pharmacist.