- the cold lasts for more than ten days
- there is high fever or if fever and pain persist for more than two days despite medication
- the phegm expelled by coughing has a yellowish-green color. In this case there might be bacterial involvement which, in some cases, should be treated with antibiotics
- the throat becomes quite painful or if the pain lasts for more than three days
- the tongue or the mucous membranes of the throat display white to yellow coatings because this might signal a fungal infection
- the tonsils display stippling spots
