What Are the Stages of Flu Symptoms?

Reviewed on 5/16/2022
A child sick with the flu lying in bed as a parent's hand is placed on his forehead
Symptoms of the flu usually come on suddenly and can last several weeks. Flu symptoms tend to occur in three stages and include Days 1 through 3 in the first stage with a sudden appearance of symptoms, Day 4 in the second stage as new symptoms appear, and Day 8, when symptoms decrease.

The flu (influenza) is a respiratory illness that can cause mild to severe illness that can result in hospitalization or death. The two main types of flu (influenza) virus, types A and B, are responsible for seasonal flu epidemics each year.

How Long Does the Flu Last?

Symptoms of the flu usually come on suddenly and can last several weeks. 

Flu symptoms tend to occur in three stages and include the following: 

  • Days 1 through 3 
  • By day 4
    • Cough, some mild chest discomfort, and hoarse, dry, or sore throat become more noticeable
    • Fatigue
    • Fever and muscle aches decrease
  • By day 8
    • Symptoms decrease
    • Cough and tiredness may persist for one to two weeks or longer

What Tests Are Used to Diagnose the Flu?

The flu (influenza) is diagnosed based upon the patient’s symptoms and a physical examination. 

Tests used to diagnose the flu include:

  • Rapid molecular assays 
  • Rapid influenza diagnostic tests (RIDTs) 
  • Other specialized flu tests may be used in hospitals or state public health laboratories

What Is the Treatment for the Flu?

The flu (influenza) is treated with home remedies and antiviral medicines in some cases. 

Home remedies to help relieve symptoms of the flu include: 

  • Rest
  • Drinking plenty of fluids
  • Saline nasal spray or drops
  • Clean humidifier or cool mist vaporizer
  • Inhaling steam from a bowl of hot water or shower
  • Sucking on lozenges 
    • Do not give lozenges to young children because they pose a choking hazard
  • Over-the-counter (OTC) medicines for relief of symptoms

Antiviral medications may be used to treat the flu. Antivirals for the flu work best when taken within 48 hours of the onset of symptoms to help reduce the severity and duration of the illness. 

Antiviral medications used to treat the flu include: 

Does the Flu Vaccine Prevent the Flu?

The Centers for Disease Control (CDC) recommends everyone 6 months and older get an annual flu vaccine as the best way to prevent the flu (influenza). 

While a flu shot is not 100% effective in preventing the flu, it can reduce the severity and duration of flu illnesses, doctors’ visits, and missed work and school due to the flu, as well as prevent flu-related hospitalizations and deaths.

Reviewed on 5/16/2022
Image Source: iStock Images