Flu Signs and Symptoms

What are the signs and symptoms of influenza?

• Sym​ptoms develop 1 to 3 days after a person has become infected.
• Influenza has a sudden onset with fever, headache, muscle aches, joint pain, sore throat, tiredness and cough.
• Fever may not be prominent in children or the elderly.
• Nausea, vomiting and diarrhea are not common in adults but may occur in children.
• Influenza is more severe than the common cold.
• In severe cases, influenza may result in pneumonia, bronchitis, kidney or heart failure.
• Most symptoms resolve in 5 to 7 days, but cough and fatigue can last 2 weeks or more.

What if my child or I have symptoms?

• Do not attend daycare, school, place of work, social gathering places (e.g. coffee shop) or volunteer activities while symptoms are present.
• If you are a health-care worker, do not attend work for 5 days after onset of symptoms.

​S​hould I call my doctor?

​Call your doctor if any of the following symptoms develop:

• Chest pain or pressure
• Shortness of breath while resting
• Difficult or painful breathing
• Coughing up bloody sputum
• Wheezing
• Drowsiness, disorientation or confusion
• Extreme pain in your ear
• A fever greater than 39 degrees Celsius that lasts more than 4 days or is getting worse
• You start to feel better and suddenly get a fever over 39 degrees Celsius and start to feel sick again

For children, call the doctor if the child:​

• Has heart or lung disease or a chronic illness that requires regular medical care
• Has a disease or is taking drugs or treatments that affect the immune system
• Has trouble breathing
• Is less than 6 months old and has a temperature over 38.5 degrees Celsius
• Is irritable and cannot be calmed down
• Is listless and doesn't play with toys, drinks little fluid and does not urinate at least every 6 hours when awake
• Has severe vomiting or diarrhea
• Symptoms improve and then suddenly get worse.