In the past, therapy has been given for 2-3 weeks but recent thinking is that rhinosinusitis is a mucosal disease that may be treated appropriately with shorter courses of therapy using more effective agents. Therefore, 5-10 days of levofloxacin 500 mg o.d. is seen as appropriate, although it is generally prescribed for 10-14 days. The drug is well tolerated and well absorbed, with evidence that levofloxacin 750 mg o.d. or levofloxacin 1,000 mg o.d. could be safely used for patients with more difficult to treat infections, such as Pseudomonas aeruginosa.