flu with fever
Informed by recognized medical guidance
Overview
The flu (influenza) is a common viral infection of the nose, throat, and lungs. When you have the flu, a fever is your body turning up its internal temperature to help fight the virus. For most people, the flu with fever is unpleasant but improves within a week or two. However, it can sometimes lead to serious complications, so it helps to know what to watch for.
Key facts
- The flu is caused by a virus, not by cold weather or getting wet.
- A fever with the flu is often high and may last 3 to 4 days.
- The flu is very contagious and spreads through tiny droplets when someone coughs, sneezes, or talks.
- Most people recover without needing medical treatment, but the flu can be dangerous for young children, older adults, and people with certain health conditions.
Yes. The flu is very common. Every winter, millions of people around the world catch the flu. Most cases are mild, but each season can be serious for some people.
The flu can affect anyone, but it is more likely to cause severe illness in young children (especially under 5), adults over 65, pregnant women, and people with chronic conditions like asthma, diabetes, or heart disease.
Symptoms
- Trouble breathing or shortness of breath
- Pain or pressure in the chest or belly
- Sudden dizziness, confusion, or not waking up properly
- Seizures or convulsions
- Lips or face turning blue or purple
- Severe weakness or inability to stay awake
- For children: being very irritable, not waking up, or having trouble breathing
- ⚠A fever that keeps coming back or lasts more than 3 to 4 days in adults (or 3 days in children)
- ⚠A cough that becomes very painful or brings up colored mucus
- ⚠Signs of dehydration – not urinating much, dry mouth, crying without tears
- ⚠Not getting better after a week, or getting worse again after starting to improve
- ⚠Older adults: feeling unusually weak, confused, or breathless
- ⚠Being in a high-risk group and having flu symptoms
Common symptoms
- Fever or feeling feverish/chills
- Body aches and muscle pains
- Headache
- Cough, often dry
- Sore throat
- Runny or stuffy nose
- Extreme tiredness (fatigue)
- Sometimes vomiting and diarrhea (more common in children)
Symptoms in children
- Fever that may appear quickly
- Vomiting and diarrhea
- Fussiness or low energy
- Poor feeding or drinking
- A barking cough (in some children)
Symptoms in older adults
- May not always have a high fever, even with serious flu
- New confusion or sleepiness
- Weakness or dizziness
- Loss of balance
- Dry cough and shortness of breath
- Less interest in eating or drinking
Causes
Main causes
- Influenza viruses (types A and B) are the cause of the flu.
- The virus spreads through droplets when an infected person coughs, sneezes, or talks.
- You can also get the flu by touching a surface with the virus and then touching your mouth, nose, or eyes.
Risk factors
- Being around many people during flu season (schools, offices, public transport)
- Having a weakened immune system
- Living or working in a care facility such as a nursing home
- Being very young or older than 65
- Having a chronic condition such as asthma, diabetes, heart disease, or kidney disease
- Being pregnant
When to see a doctor
See a doctor urgently if:
- Symptoms that are getting worse instead of better
- A fever above 103°F (39.4°C) in adults, or any fever in a baby under 3 months
- Difficulty staying hydrated or urinating less often
- You are in a high-risk group (older, pregnant, or chronic illness) and have flu symptoms
- Older adults with confusion, weakness, or shortness of breath
Book a routine appointment if:
- A fever that lasts longer than 3 to 4 days
- You get better and then develop a new fever and a worse cough
- You have an underlying health condition and want advice on managing the flu
- You are unsure whether your symptoms could be something more serious
Diagnosis
A doctor can usually diagnose the flu by asking about your symptoms and examining you. During flu season, no test may be needed. However, tests can help in some cases, especially if you are at higher risk or in the hospital.
Tests that may be done
- A rapid influenza test using a nasal or throat swab – results in about 15 minutes
- A more sensitive PCR test (also from a nose/throat swab) – sent to a lab
- In some cases, a chest X-ray to check for pneumonia if your breathing is affected
What to expect at your appointment
The doctor will ask when your symptoms started, whether you have a fever, and about your overall health. They may check your temperature, listen to your lungs, and look at your throat and nose. They will explain if any test is needed and give you advice on treatment and follow-up.
Treatment
Most people can manage flu with fever at home. The goal is to let your immune system fight the virus while you stay as comfortable as possible. Antibiotics do not work for the flu because it is a virus, not bacteria. In some cases, a doctor may prescribe an antiviral medicine (taken by mouth or inhaled), especially if started within 48 hours of symptoms.
Self-care at home
- Rest in bed and get plenty of sleep
- Drink lots of fluids – water, broths, clear soups – to keep fever from causing dehydration
- Use a cool (not cold) compress on your forehead for comfort, but avoid ice baths or rubbing alcohol
- Use a saltwater gargle or suck on ice chips for a sore throat
- Avoid alcohol and smoking
- Stay home until your fever has gone for at least 24 hours without using fever-reducing medicine
Medical treatments
Fever-reducing medicines and pain relievers (such as paracetamol or ibuprofen) can help you feel more comfortable – but always ask your pharmacist or doctor about the right choice for you and especially for children. Never give aspirin to anyone under 18 with flu-like symptoms. Antiviral medicines may be prescribed for people at high risk or with severe symptoms, but they are not a substitute for the flu vaccine. Your doctor will decide if antivirals are appropriate for you.
Living with this condition
Plan to take it easy. It is normal to feel tired for several days or even up to two weeks. As your fever drops, gradually return to normal activities. Listen to your body – rest when you feel tired.
Lifestyle tips
- Wash your hands often with soap and water or use hand sanitizer
- Cover coughs and sneezes with a tissue or your elbow
- Keep your home well ventilated and clean frequently touched surfaces
- Stay hydrated and eat small, easy-to-digest meals when you feel like eating
Diet and exercise
You may lose your appetite. Eat light foods like toast, rice, bananas, or clear soup when you can. Drink enough fluid so your urine is pale. Do not exercise while you have a fever – wait until you are fever-free and your energy returns before resuming normal exercise.
Mental health and emotional wellbeing
Being ill can make you feel low, impatient, or frustrated. That is a normal response. Give yourself time to recover, and keep in touch with friends or family by phone or video. If you feel very down for more than a few weeks after your illness, consider speaking to your doctor.
Prevention
There is no way to guarantee you will never get the flu, but vaccines and good hygiene greatly reduce your risk.
Vaccines
A yearly flu vaccine is the best way to protect yourself and others. It is offered to everyone over 6 months, especially those at higher risk. Getting the vaccine before or during flu season can prevent the flu or make it milder.
Complications
If left untreated
- Pneumonia (a lung infection)
- Ear and sinus infections
- Dehydration
- Worsening of long-term conditions such as asthma, heart failure, or diabetes
- Inflammation of the heart (myocarditis)
- In rare cases, inflammation of the brain (encephalitis)
Long-term outlook
With rest and care, most people feel significantly better within 1 to 2 weeks. A dry cough and tiredness may linger a bit longer. If you are high risk, early medical advice can make a big difference. The flu is usually a short illness, but it deserves respect and attention.
Find support
International organisations
Local organisations
- UK National Health Service (NHS) ↗ · United Kingdom
External links open third-party websites. Ruqelo Health is not responsible for external content. Listing an organisation does not imply endorsement.
Always verify with your doctor
Health guidelines vary by country and region. The information in this article is based on international clinical guidelines but may not reflect the specific guidelines, medications, or practices in your country. Always discuss your health concerns with your own doctor or healthcare provider, and refer to your local national health guidelines where available.
Important notice This information is for educational purposes only. It does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider about your specific situation. If you are experiencing a medical emergency, call your local emergency services immediately.
Related conditions
Sources and guidance
This article is educational and is prepared with reference to recognized health information and clinical guidance sources where available. Specific source links may vary by topic.
Last updated: July 31, 2026
Educational note: This information is for education only and is not a diagnosis.
Use it to support, not replace, advice from a licensed clinician.
If symptoms are severe, worsening, or urgent, call your local emergency number or seek emergency care.