The best way to prevent sinusitis is to avoid or quickly treat flus and colds:
Eat plenty of fruits and vegetables, which are rich in antioxidants and other chemicals that could boost your immune system and help your body resist infection.
Get an influenza vaccine each year.
Wash your hands often, particularly after shaking hands with others.
Other tips for preventing sinusitis:
Avoid smoke and pollutants.
Drink plenty of fluids to increase moisture in your body.
Take decongestants during an upper respiratory infection.
Treat allergies quickly and appropriately.
Use a humidifier to increase moisture in your nose and sinuses.