How Long Does a Flu Last

The flu, or influenza, is a common respiratory virus that affects thousands of Canadians each year. In many cases, the illness passes within 3-14 days without severe complications. Understanding the typical duration of the flu can help you manage your symptoms more effectively and to know when to seek medical attention. 

Read on to learn more about how long the flu can last, the factors that influence its duration, and the key stages of the illness.

How long can the flu last?

Generally, the flu lasts about one to two weeks, but this timeline can be shorter or longer, based on your age, overall health, and the presence of any underlying conditions affecting your immune system. 

According to Infection Prevention and Control Canada (IPAC), the average duration of flu symptoms in Canadians has remained consistent, with most people recovering within seven to 10 days. However, some people may experience lingering symptoms, particularly fatigue and cough, which can last for weeks. 

Factors influencing the duration of the flu

Several factors can influence how long the flu lasts:

• Age: Younger children and older adults tend to have longer recovery times due to weaker immune systems. 
• Underlying health conditions: Individuals with chronic health conditions, such as asthma, diabetes or heart disease, may experience more severe symptoms and a longer recovery period. 
• Vaccination status: Those who have received the flu vaccine may still get the flu, but their symptoms are typically milder, and the duration of the illness is often shorter compared to those who are unvaccinated.
• Immune system strength: A strong immune system can help reduce the severity and duration of flu symptoms. Factors such as stress levels, sleep quality and overall health can impact the immune response.
• Viral strain: Different strains of the flu virus have varying durations and severities of illness. The H3N2 strain (influenza A) is associated with more severe symptoms and a longer duration of symptoms, particularly in older adults. During the 2022-2023 flu season, the H3N2 strain was predominant in Canada, accounting for 93% of tested cases.

Typical timeline of symptoms

After exposure to the flu virus, you may start to experience symptoms within 24 to 48 hours. It typically progresses through several stages, each with its own set of symptoms. 

Initial symptoms (Days 1-3)

The flu often begins suddenly, with a rapid onset of symptoms. The first few days are usually marked by:

• Fever
• Chills and sweats
• Fatigue and weakness
• Headache and muscle aches
• Sore throat and dry cough

Peak of symptoms (Days 3-7)

Around the third to fourth day, flu symptoms typically peak in intensity. This period is generally the most uncomfortable and includes symptoms like:

• Persistent fever
• Severe fatigue
• Worsened cough
• Nasal congestion and runny nose
• Increased throat pain
• Gastrointestinal symptoms like diarrhea

Recovery period (Days 7-14)

The recovery period varies, but most people begin to feel better after a week, with a decreasing fever, reduced fatigue, and clearing nasal congestion. While the cough may ease up, it can persist for some time.

Preventing the flu

Prevention is the best strategy to protect yourself from the flu. Enjoy a balanced diet, get plenty of sleep, and practice good hygiene, including frequent handwashing. 

Annual flu vaccinations are effective for reducing the risk of contracting the flu. In Canada, the flu vaccine’s effectiveness is estimated to be about 50%, equally reducing the risk of severe illness and hospitalization.

If you think you might have the flu, cover your mouth and nose when you cough or sneeze to help prevent the spread of the virus. 

When to call your doctor

While most people recover from the flu without complications, there are situations where medical attention is necessary. It’s important to call your doctor if:

• Symptoms worsen: If symptoms become more severe after the initial few days, such as a severe or worsening cough, or if they don’t start to improve after a week, contact your doctor.
• Difficulty breathing: Shortness of breath or difficulty breathing is a serious symptom that requires immediate attention.
• Chest pain: Any chest pain — especially when accompanied by other flu symptoms — should be evaluated by a healthcare professional.
• High fever: A fever that persists for more than five days or is very high (39.4°C or higher) and unresponsive to medication may indicate a secondary infection.
• Confusion or dizziness: These symptoms, particularly in older adults, can be signs of complications like dehydration or pneumonia.

If you’ve got young ones heading back to school, quick and convenient access to healthcare can help get your family back to peak health when the flu comes to visit. 

Maple makes it easy to talk to a primary care provider online about your flu symptoms 24/7/365 in minutes over secure text, audio, or video call. Primary care providers, like doctors and nurse practitioners, can assess your symptoms and, at their discretion, provide a prescription to help with symptoms if needed. 

Understanding the typical course of the flu and knowing when to seek help can make a significant difference in the management of this common illness. By taking preventive measures and paying attention to your body’s signals, you’ll be able to navigate flu season with greater confidence and less discomfort.

The information presented here is for educational purposes and is not meant to replace the advice from your medical professional. Virtual care is not meant for medical emergencies. If you are experiencing an emergency like chest pain or difficulties breathing, for example, please call 911 or go to your nearest emergency room.