 [ Symptoms ] when am i no longer contagious i caught a cold then three days later developed bronchitis i understand the cold has a three day contagiousness window  one day before you know you are ill and two days following but what happens when the cold develops into bronchitis am i contagious again when the bronchitis symptoms appear bottom line when am i clear to return to work so i do not infect others [ Disease ] bronchitis caused by viruses are usually contagious therefore you should be careful during acute episodes and even a few days after the symptoms subside general measures of hygiene must be followed to prevent spread of contagious infections