Sinusitis can be either acute (sudden) or chronic (long-term). With chronic sinusitis, the infection or inflammation does not completely go away for 8 weeks or more.
What causes sinusitis?

Sinusitis can be caused by three things:

• Viruses.
• Bacteria.
• Fungi.

When the lining of the sinus cavities gets inflamed from a viral infection like a cold, it swells. This is viral sinusitis. The swelling can block the normal drainage of fluid from the sinuses into the nose and throat. If the fluid cannot drain and builds up over time, bacteria or fungi (plural of fungus) may start to grow in it. These bacterial or fungal infections can cause more swelling and pain. They are more likely to last longer, get worse with time, and become chronic.

Treatment:
Viral sinus infections usually go away on their own within 10 to 14 days. Antibiotics don't work for viral infections. But there are some things you can do at home to help relieve your symptoms:

• Drink plenty of fluids.
• Try over-the-counter pain relievers and decongestant pills to help relieve the pain and pressure in your head and face.
• Put a hot, damp towel or gel pack on your face for 5 to 10 minutes at a time, several times a day.
• Breathe warm, moist air from a steamy shower, a hot bath, or a sink filled with hot water.
• Use saltwater nose drops to help keep the nasal passages open and wash out mucus and bacteria.

Bacterial infections can be treated with antibiotics. You will probably feel better in a few days, but some symptoms may last for several weeks. You may need to take the medicine for a longer time if you have chronic sinusitis.

If you have a fungal infection--which is not common--antibiotics won't clear up your sinusitis. With this type of infection, you may need treatment with antifungal medicines, steroid medicines, or surgery.