Symptoms of Influenza

Flu symptoms usually begin suddenly, about 1 to 4 days after exposure.

Common symptoms

• Fever, often high, and chills
• Dry cough
• Sore throat
• Runny or blocked nose
• Muscle and body aches
• Headache
• Marked tiredness and weakness
• Some people, especially children, have vomiting or diarrhoea.

Not everyone with flu has a fever.

How long

Fever usually settles in 3 to 5 days. Cough and fatigue can linger for 1 to 2 weeks or more.

Emergency signs in adults (call 112 or 102)

• Difficulty breathing or shortness of breath
• Chest pain or pressure
• Confusion, severe drowsiness or fainting
• Seizures
• Bluish lips or face
• Severe or persistent vomiting, or signs of dehydration
• Symptoms that improve and then return with a worse fever and cough

Emergency signs in children

• Fast or laboured breathing, or ribs pulling in with each breath
• Bluish skin or lips
• Not drinking enough fluids, or no urine for 8 hours
• Being unusually sleepy, hard to wake or very irritable
• Fever with a rash
• Fever in a baby under 3 months

See a doctor early if you are

Pregnant, over 65, under 5, or have a chronic illness or weak immunity, because early treatment matters.

Key point

Most people recover at home, but warning signs and high-risk groups need prompt medical care.

Before your appointment

Note when symptoms began, your highest temperature, and any cough, breathing trouble or vomiting. List your medicines, long-term conditions, pregnancy, allergies and recent vaccines, including this year's flu vaccine. Mention contact with anyone who is ill. Ask about testing, antivirals, when to return to work or school and the warning signs that mean you should call 112 or 102.