questions have been asked and ignored so I am going to step in here and demystify a few points for non-medics which is most of us.

1 "itis" as in sinusitis or tonsillitis means swelling or inflammation. So Sinusitis is swelling of the sinuses. Most people immediately think of sinusitis as an infection but any asthmatic or person with allergies will tell you, inflamed or swollen sinuses is part of their condition and has nothing to do with infection.

2. An antibiotic is an antimicrobial. Antibiotics, fight microbes or bacteria which cause infection. Generally there are two types of infection - bacterial and viral. Antibiotics only work on bacteria although doctors often prescribe antibiotics for viral infections. The reason for this, is that one can't tell if it is viral or bacterial unless a swab is taken and tested (most don't do this they just guess)so it is treated in case it is bacteria. Sometimes it is worth giving antibiotics prophylactically (as a preventative)to stop the infection progressing to something really nasty.

3. The other kind of sinusitus is when the swelling is not caused by an infection but body itself (immune response). The drugs used by asthmatics and allergy sufferers keep the swelling or inflammation at bay. Basically they are called "anti-inflammatory" drugs and they work to calm down the immune system which is causing the inflammation.

4. Inflammation is a natural (and usually welcome) response to beasties. The immune system literally goes to war with invaders, be that infection or physical injury. Radiation is physical injury and your immune system is in there trying to control the damage. Scarring is the immune system's idea of a bandaid. Unfortunately, your immune system has got a little over excited and doesn't know when to quit. Your meds are taken to calm the immune system down to reduce the inflammation so you don't get so much pain

(There are three main types of infections, and the third is fungal)