Flu Resource Center

Overview

Flu (short for influenza) is a common illness caused by a virus that infects your nose, throat, and lungs. It usually comes on suddenly and makes you feel much worse than a normal cold. Most people get better on their own within one to two weeks, but flu can be serious for some people, so it helps to know what to watch for.

Yes. Flu spreads widely every year, usually in the colder months. Most people will catch flu at some point in their lives, and some people catch it more than once because the virus changes over time.

Anyone can get flu, including healthy children and adults. Some people are more likely to become very unwell: older adults, pregnant women, young children, and people with long-term conditions such as asthma, heart disease, diabetes, kidney disease, or a weakened immune system.

Symptoms

Common symptoms

• A sudden high temperature (fever) or feeling feverish and shivery
• Aches and pains in your muscles, often feeling worse than a cold
• Feeling very tired or exhausted
• A dry cough that may linger for a week or more
• Sore throat
• Blocked or runny nose
• Headache
• Sometimes feeling sick, or being sick or having loose stools (diarrhea)

Symptoms in children

• High fever that may cause febrile convulsions (a brief fit caused by fever) in some young children
• Being more irritable or sleepy than usual, or hard to wake
• Poor feeding or drinking less than usual
• Earache or pulling at the ears
• A barking cough or noisy breathing
• Being sick or having loose stools more often than adults
• Less common: a rash

Symptoms in older adults

• May have a lower fever than younger people, or no fever at all
• New confusion, drowsiness, or being 'not themselves'
• Falls or sudden weakness
• Poor appetite and drinking less, leading to dehydration (not enough fluid in the body)
• Worsening of an existing heart or lung condition
• A cough that may be the main or only sign

Causes

Main causes

• Infection with an influenza virus, which spreads through tiny droplets when someone coughs or sneezes
• Touching surfaces with the virus on them and then touching your mouth, nose, or eyes
• Being close to someone who is infected, especially in crowded indoor places
• The virus changes slightly each year, so past infection does not fully protect you next season

Risk factors

• Being older (roughly 65 and over) or very young (under 5, especially under 2)
• Being pregnant or having recently given birth
• Long-term conditions such as asthma, COPD (a long-term lung disease), heart disease, diabetes, or kidney disease
• A weakened immune system, for example from some medical treatments or certain illnesses
• Living in a care home or other shared living setting
• Being very overweight
• Working in healthcare or another job with close contact with many people
• Smoking

When to see a doctor

See a doctor urgently if:

• Difficulty breathing or fast, noisy breathing
• Breathing problems with chest pain
• Signs of dehydration such as dizziness, dark urine, or being very thirsty and unable to keep fluids down
• New confusion or unusual drowsiness
• A baby or young child who is not feeding, is floppy, or has fewer wet nappies
• You are pregnant, or you have a long-term condition that is getting worse
• A fever that will not settle or a cough that is becoming much worse

Book a routine appointment if:

• You are unsure whether it is flu or something else
• Your symptoms are not improving after about a week, or are slowly getting worse
• You keep getting flu-like illnesses or chest infections
• You want advice about the yearly flu vaccine
• You have a lingering cough or tiredness that worries you

Diagnosis

In most cases, a doctor or nurse can tell it is likely flu from your symptoms and the time of year. You usually do not need any tests. If your symptoms are unusual, you are very unwell, or you are in a higher-risk group, your doctor may suggest a test to confirm it.

Tests that may be done

• A swab test: a soft swab is wiped inside your nose or throat and sent to a lab to look for the flu virus
• A rapid test done in some clinics, which gives a result within minutes
• Blood tests or a chest X-ray if your doctor is checking for other problems such as pneumonia (a chest infection)
• Checking your oxygen level with a small clip on your finger if you are breathless

What to expect at your appointment

If a test is needed, it is quick and usually mild or painless. You will be asked about your symptoms, your temperature, and any long-term conditions. Most people are advised to rest at home while waiting for results. If your symptoms are mild, your doctor may not test at all and will simply give you advice on managing at home and when to come back.

Treatment

Flu is caused by a virus, so it is treated mainly with rest, fluids, and simple comfort measures while your body fights it off. Antibiotics (medicines that kill bacteria) do not work on flu. Some people who are at higher risk of becoming very unwell may be offered antiviral medicine by a doctor, which works best when started early.

Self-care at home

• Rest as much as you need, and stay home from work or school until you feel better
• Drink plenty of fluids such as water, squash, or warm drinks to avoid dehydration
• Take paracetamol or ibuprofen if suitable for you, following the label or your pharmacist's advice, to ease fever and aches
• Keep warm and comfortable, and use extra pillows at night if coughing keeps you awake
• A warm drink with honey and lemon can soothe a sore throat (do not give honey to babies under 12 months)
• Steam from a warm shower or a bowl of hot water can help a blocked nose
• Avoid smoking and smoky rooms, as smoke makes coughing worse
• Ask your pharmacist before taking cold and flu remedies, especially if you take other medicines or are pregnant

Medical treatments

For most people, treatment is about relieving symptoms and letting the body recover. A doctor may offer antiviral medicine (a medicine that targets the virus) to people who are more likely to become seriously unwell, to those with severe symptoms, or to people who live with someone at high risk. These work best when started soon after symptoms begin. Your doctor will decide whether it is right for you. If you develop a chest infection caused by bacteria, or another complication, your doctor may discuss other treatments at that point. Always check with a pharmacist or doctor before combining medicines, and never take leftover medicines from a previous illness.

When is surgery considered?

Surgery is not used to treat flu. In rare cases, a person who develops a serious complication may need hospital care, but this is not part of routine flu treatment.

Living with this condition

While you are unwell, take things slowly. Plan for a few days of rest, keep drinks within easy reach, and ask family, friends, or neighbours for help with shopping or childcare if you can. Stay away from others as much as possible while you have a fever so you do not pass the virus on. Cover coughs and sneezes with a tissue, throw tissues away, and wash your hands often.

Lifestyle tips

• Go back to normal activity gradually; do not rush back to work or exercise while you still feel exhausted
• Keep up your fluid intake, especially if you have a fever or are sweating
• Eat light, simple meals if your appetite is low, and return to normal eating as you feel better
• Avoid alcohol while you are unwell and recovering
• Get plenty of sleep; good sleep helps your body fight infection
• Keep rooms ventilated (let fresh air in) when you have visitors

Diet and exercise

There is no special diet that cures flu. Aim for regular fluids and simple, nourishing food such as soup, toast, fruit, and yoghurt when you feel able. Once your fever has gone and your energy is returning, gentle activity like a short walk is fine. Build up slowly over a week or two. If exercise makes you feel wiped out, rest and try again later. If you have a heart or lung condition, ask your doctor or nurse for advice on returning to activity.

Mental health and emotional wellbeing

Being ill with flu can feel lonely, boring, or worrying, especially if you live alone or are caring for others. It is normal to feel low or frustrated when you are stuck in bed. Keep in touch with people by phone or video calls, and tell someone if you are struggling. If you feel persistently low, anxious, or hopeless, speak to your doctor. If you ever have thoughts of harming yourself, contact your local emergency number or a crisis line in your country right away.

Prevention

You cannot fully prevent flu, but you can greatly lower your risk and the risk of passing it on. The flu vaccine each year is the single most effective step for most people. Everyday habits such as hand washing, covering coughs, and staying home when unwell also make a real difference.

Vaccines

A flu vaccine is offered every year, usually in autumn, because the virus changes over time. It is recommended for people at higher risk, including older adults, pregnant women, young children, and people with certain long-term conditions, as well as those who care for them or work in health and social care. The vaccine does not cause flu. It may cause a slightly sore arm or mild tiredness for a day or two. Ask your doctor, nurse, or pharmacist whether it is right for you and when to get it.

Screening programmes

There is no screening test for flu in people without symptoms. The focus is on prevention through vaccination and good hygiene. If you are in a higher-risk group, your doctor may invite you for a yearly review of your long-term condition, which is a good chance to ask about flu protection.

Complications

If left untreated

• Pneumonia (a serious chest infection), which is more likely in older adults, pregnant women, and people with long-term conditions
• Bronchitis (inflammation of the airways) with a cough that lasts for weeks
• Ear infections and sinus infections
• Dehydration, especially in young children and older adults
• Worsening of existing conditions such as asthma, COPD, heart disease, or diabetes
• Rarely, serious problems such as inflammation of the heart or brain, or a severe whole-body reaction called sepsis

Long-term outlook

The good news is that most people recover fully from flu within one to two weeks, though a cough and tiredness can linger a little longer. Rest, fluids, and knowing when to get help are the key steps. If you are in a higher-risk group, the flu vaccine and early advice from your doctor can greatly reduce the chance of serious illness. Most people who do develop complications still recover well with treatment.

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