(HealthDay News) -- If your cough has persisted for three weeks or longer, it's time to see a doctor.

Here are additional warning signs, courtesy of the American Academy of Family Physicians, that your cough requires medical attention:

• Coughing up thick phlegm that is yellow or green in color.
• Wheezing when you breathe.
• Fever of 101 degrees Fahrenheit or higher.
• Losing weight unexpectedly.
• Excessive sweating at night.
• Coughing up blood.