Acute sinusitis means that the infection develops quickly (over a few days) and lasts a short time. Many cases of acute sinusitis last a week or so but it is not unusual for it to last 2-3 weeks (that is, longer than most colds). Sometimes it lasts longer. Sinusitis is said to be acute if it lasts from 4-30 days and subacute if it lasts 4-12 weeks. A mild bout of acute sinusitis is common and many people will have some degree of sinusitis with a cold. However, severe acute sinusitis is uncommon. Most people only ever have one or two bouts of acute sinusitis in their life. However, some people have recurring bouts of acute sinusitis.
Chronic sinusitis means that a sinusitis becomes persistent and lasts for longer than 12 weeks. Chronic sinusitis is uncommon