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Symptoms typically occur between one and three days after being infected with a cold or flu (influenza) virus. On average, symptoms last up to one week, although sometimes they may last two weeks.

Symptoms of a cold and the flu may be similar. The primary difference is that cold symptoms are generally mild and come on gradually, whereas flu symptoms are usually more severe, begin suddenly and last longer than a cold.

Common signs and symptoms of colds and the flu include:

• Throat irritation. An itchy, sore or scratchy throat is usually the first symptom noticed with the onset of a cold. This may also occur with the flu, although it is generally not the first symptom noticed.
  
  
• Nasal obstruction. A stuffy nose can cause nasal congestion, making it hard to breathe. By the second or third day of a cold or the flu, nasal problems usually predominate.
  
  
• Runny nose (rhinorrhea). Mucus may be clear, yellow or green in color. The color and consistency of mucus may change during the duration of a viral infection.
  
  
• Sneezing.
  
  
• Coughing.
  
  
• Low-grade fever (100 to 101 degrees Fahrenheit or 37.2 to 37.8 degrees Celsius). Fever is not generally a symptom of the common cold, and is more often associated with the flu.
  
  
• Fatigue.
  
  
• Muscle pain.
  
  
• Headache.
  
  
• Loss of appetite.
  
  
• Watery or itchy eyes.
  
  
• Chills.

A cold usually begins with throat irritation. Nasal problems, such as a stuffy or runny nose, usually become the dominant symptom after the second or third day of the cold. Coughing is common in children with a cold. Fever is not common with a cold.

With the flu, symptoms usually begin with muscle aches for the first few days, then a stuffy nose and/or sore throat may occur, which may linger. Fever, fatigue, muscle aches and a dry cough are more common with the flu than with colds. Additional symptoms that occur with the flu, but not a cold, include dizziness, nausea or vomiting, abdominal pain and diarrhea.

For signs of a cold or the flu specific to infants, see Infant issues for cold & flu.

Parents should seek immediate medical attention for their child if symptoms are severe or persist, or if any of the following occur:

• Coughing up a lot of mucus
  
  
• High-grade fever (104 degrees Fahrenheit or higher – 40 degrees Celsius or higher) or prolonged fever (of 102 degrees Fahrenheit – 38.9 degrees Celsius)
  
  
• Earache or drainage from the ear
  
  
• Swollen glands in the throat
  
  
• Extreme difficulty with swallowing
  
  
• Unusual fatigue
  
  
• Vomiting or abdominal pain
  
  
• Increasing pain (e.g., headaches, pain in the face or throat)
  
  
• Chest pain or stomach pain
  
  
• Breathing difficulties (e.g., shortness of breath, rapid breathing, wheezing)
  
  
• Cyanosis (skin that turns bluish in color from a lack of oxygen)
  
  
• Signs of dehydration (e.g., sunken eyes, lack of tears, inadequate urination, dry skin)
  
  
• Changes in mental state (e.g., extreme irritability, seizures, changes in alertness)