Are most cases of acute sinusitis viral? how long before symptoms lessen and you start to feel better? at what point should you visit the dr?

Most viral: Yes, most cases of sinusitis are viral. Typical symptoms lat 5-7 days before slowly resolving. Indications that you may have a bacterial infection are fevers >100, severe sinus pain, symptoms longer than 10 days or initial improvement before worsening of your symptoms. Obviously, see your doctor if you believe you have bacterial infection, but they can also help with meds for viral symptoms.