Flu

Overview

Flu — short for influenza — is an illness caused by a virus that infects your nose, throat and lungs. It comes on fast, often within a day or two, and usually hits harder than a common cold. Most people feel very tired and achy and need to rest at home for about a week, though a cough and tiredness can linger a bit longer.

Yes. Flu is very common and spreads in waves, usually in the colder months. Most people catch flu at some point in their lives, and some people catch it more than once because the virus keeps changing.

Anyone can get flu, including healthy children and adults. It tends to be more serious for people aged 65 and over, pregnant women, very young children, and people with long-term conditions such as heart, lung, kidney or liver disease, diabetes, or a weakened immune system.

Symptoms

Common symptoms

• A sudden fever or feeling shivery and hot
• Aches and pains in your muscles, often feeling 'bruised all over'
• Feeling very tired or wiped out
• A headache
• A dry cough that can last a week or more
• A sore throat
• A blocked or runny nose
• Sometimes feeling sick, vomiting or loose stools (more common in children)

Symptoms in children

• High fever, sometimes with febrile seizures (a fit caused by a sudden rise in temperature)
• Being irritable, clingy or very sleepy
• Poor feeding or drinking less than usual
• Ear pain or ear infection
• Vomiting or tummy upset, which happens more often than in adults
• A sore throat and cough that may sound barking or croup-like

Symptoms in older adults

• Fever may be low or even absent
• Sudden confusion or new forgetfulness
• Feeling weak, dizzy or unsteady on your feet, with a higher risk of falls
• Breathlessness or a worsening of an existing heart or lung condition
• Loss of appetite and drinking less, which can lead to dehydration

Causes

Main causes

• Influenza viruses, mainly two types (known as A and B), which infect the nose, throat and lungs
• Breathing in droplets in the air when someone with flu coughs or sneezes near you
• Touching a surface with the virus on it, then touching your eyes, nose or mouth
• The virus changes slightly over time, which is why you can catch flu more than once and why the vaccine is updated each year

Risk factors

• Being aged 65 or over
• Being pregnant
• Being very young, especially under 2 years old
• Long-term conditions such as asthma, COPD, heart disease, diabetes, kidney or liver disease
• A weakened immune system, from illness or certain treatments
• Living or working in crowded places such as care homes, hospitals or shared housing
• Smoking, which irritates the lungs and raises the risk of complications

When to see a doctor

See a doctor urgently if:

• You or your child have trouble breathing, chest pain, or feel very unwell very quickly
• You are confused, very sleepy or hard to wake
• There are signs of dehydration, or a baby is feeding much less than usual
• You are pregnant, over 65, or have a long-term condition and think you have flu
• A fever in a baby under 3 months old

Book a routine appointment if:

• You are not sure whether it is flu or something else
• Symptoms are not improving after about a week
• You keep getting flu-like illnesses and want advice on prevention
• You want to ask about the flu vaccine or whether it is right for you
• You have questions about which over-the-counter remedies are safe with your other medicines

Diagnosis

Usually a doctor or nurse can tell it is likely flu from your symptoms, the time of year and whether flu is going around. Flu comes on much faster than a cold and usually brings fever, aches and deep tiredness. In most cases no tests are needed.

Tests that may be done

• A swab from your nose or throat, sometimes used in hospital or for people at high risk
• A breathing test or chest check if there are concerns about the lungs
• Blood tests if you are very unwell or your doctor wants to check for other problems

What to expect at your appointment

If you contact a health service, you may be asked to describe your symptoms by phone or video call rather than come in, to avoid spreading the virus. If you do attend, you may be asked to wear a mask. Your clinician will check your breathing, temperature and hydration, and ask about any long-term conditions. They will explain what to watch for and when to get back in touch.

Treatment

Most flu treatment is about helping your body rest and recover while easing your symptoms. Antibiotics do not help because flu is caused by a virus. A doctor may consider antiviral medicine for some people at higher risk of serious illness, and it works best when started early — so it is worth seeking advice quickly if you are in a higher-risk group.

Self-care at home

• Rest as much as you need to, and stay home while you have a fever
• Drink plenty of fluids — water, warm drinks and soup all count
• Take small, regular meals if you can manage them; light food is fine
• Keep warm and comfortable, but do not over-bundle yourself or a child
• Ask your pharmacist which over-the-counter remedies are suitable for you, especially if you take other medicines, are pregnant, or are treating a child
• Keep away from others as much as possible to avoid spreading the virus, and cover coughs and sneezes
• Wash your hands often and keep shared surfaces clean

Medical treatments

If you are at higher risk of serious illness, a clinician may offer antiviral medicine, which works best when started within the first day or two of symptoms. Some people, such as those with a weakened immune system or who become very unwell, may need hospital care for oxygen, fluids or monitoring. For a cough that is not settling, or if a secondary bacterial infection is suspected, your doctor will advise on the right approach. Always check with a pharmacist or doctor before taking any medicine, including ones you buy without a prescription.

When is surgery considered?

Surgery is not a treatment for flu.

Living with this condition

Expect to feel tired for a while, even after the fever has gone. Plan for a slow return to normal life, and do not push through if you feel wiped out. Keep loose routines, drink often, and let family or friends help with shopping and meals while you recover. Try to stay away from work, school or busy places while your temperature is high.

Lifestyle tips

• Get back to gentle activity gradually, starting with short walks when you feel ready
• Keep hands clean and cover coughs and sneezes, even after you feel better
• Air out rooms now and then, and avoid crowded places while you are unwell
• If you smoke, stopping is one of the best things you can do for your lungs — ask your doctor or pharmacist for support
• Keep up to date with your yearly flu vaccine

Diet and exercise

While you are ill, the aim is simply to drink enough and eat what you can manage. There is no special flu diet — warm drinks, soups and light meals are comforting and easy to keep down. When your fever has settled and your energy is coming back, build exercise up gently over a week or two. Do not start hard training until you feel fully recovered, especially if you had chest symptoms.

Mental health and emotional wellbeing

Being ill and stuck at home can feel lonely, boring or worrying, especially if you are caring for others or missing work or school. Feeling low or anxious for a few days is normal. If low mood or anxiety lasts more than a couple of weeks, or if you have thoughts of harming yourself, reach out to a healthcare professional or a crisis support service in your area right away — you deserve help and you are not alone.

Prevention

You can lower your risk, though no single step is perfect. The flu vaccine is the best-known protection, and simple habits help too: washing your hands often, covering coughs and sneezes, staying home when unwell, and avoiding close contact with people who are ill.

Vaccines

A flu vaccine is offered each year, usually in autumn, because the virus changes and protection fades over time. It is recommended for people at higher risk — including older adults, pregnant women, young children, carers, and people with long-term health conditions — and is often offered to health and care workers too. Ask your doctor, nurse or pharmacist whether it is right for you. The vaccine cannot give you flu, and mild soreness or a short-lived achiness afterwards is common.

Screening programmes

There is no screening test for flu in the general population. Testing is only used when it will change the care someone receives.

Complications

If left untreated

• Chest infections such as pneumonia, especially in older adults and people with lung disease
• Worsening of long-term conditions like asthma, diabetes or heart disease
• Dehydration, particularly in young children and older adults
• Ear infections and sinus infections
• Rarely, inflammation of the heart, brain or muscles, or a serious whole-body reaction
• A lingering cough and tiredness that can last several weeks

Long-term outlook

For most people, flu is an unpleasant but short illness, and full recovery within one to two weeks is usual. A cough or tiredness can linger a little longer and still settle. If you are in a higher-risk group, getting advice early makes a real difference, and the flu vaccine each year helps protect you. Most people who develop complications recover well with treatment — so the key is to rest, watch for warning signs, and ask for help early if something feels wrong.

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