Influenza (flu): symptoms, care and prevention

Influenza, often called flu, is an infection caused by influenza viruses. It affects the breathing passages and can make a person feel unwell quite suddenly. Influenza is different from a simple cold because fever, body aches and marked tiredness can be more prominent. Influenza is a contagious viral illness that can cause sudden fever, aches, cough, tiredness and throat symptoms.

People with influenza often develop chills, a cough, fatigue, muscle aches and a sore throat. Some also have headache, reduced appetite, a runny nose or joint pain. Children may be irritable or eat less than usual. Symptoms can vary between people and across episodes.

Influenza viruses pass between people mainly through respiratory droplets and close contact. Touching a contaminated surface and then touching the eyes, nose or mouth may also contribute. A person can spread the virus before they recognise that they are ill, so practical infection-control habits matter.

Illness commonly begins abruptly and then improves with rest, fluids and time. Cough and low energy may linger after the fever settles. Recovery can take longer for older adults, young children, pregnant people and people with long-term health conditions. Worsening breathlessness, confusion, chest pain, inability to keep fluids down, or a child who is difficult to wake needs prompt medical assessment.

Anyone can catch influenza. More serious illness is more likely in very young children, older adults, pregnant people, and people with conditions affecting the heart, lungs, immune system or metabolism. These factors do not predict exactly how one person will feel; they help clinicians decide who may need earlier review.

A clinician usually considers the symptom pattern, the examination and current circulation of respiratory viruses. Testing may be used when it would change treatment, infection-control decisions or care for someone at higher risk. An assessment also checks for signs of dehydration, breathing difficulty or a complication.

Care focuses on rest, drinking enough fluid and easing fever or discomfort with medicines that are suitable for the person. Antiviral medicine may be considered early in illness for selected people, particularly those at greater risk of complications. Antibiotics do not treat influenza itself because it is caused by a virus. A GP can tailor advice to age, pregnancy, medical conditions and regular medicines.

Stay home while acutely unwell where possible, rest, and take small frequent drinks if appetite is low. Keep track of breathing, alertness and urine output. Reduce close contact with people who may be vulnerable, and do not share cups, cutlery or towels. Seek advice if your usual medical condition becomes harder to manage.

Influenza can sometimes be followed by pneumonia or worsening of conditions such as asthma or heart disease. A fever in a child can be associated with febrile seizures; any seizure needs urgent medical attention. New severe symptoms or a return of fever after initial improvement deserves assessment.

Seasonal flu vaccination can reduce the chance of influenza and is particularly worth discussing for people at higher risk. Handwashing, covering coughs and sneezes, cleaning frequently touched surfaces, and improving airflow in shared indoor spaces can reduce transmission. If you are ill, limiting close contact helps protect others.

A GP consultation is a sensible starting point for symptoms that are concerning, prolonged or complicated by another health condition. Telemedicine may suit a stable person who needs advice without travelling, while urgent in-person care is appropriate for severe breathing difficulty, chest pain, confusion or dehydration.