Nasal Steroids, Irrigation, Oral Antibiotics, and Subgroup Targeting for Effective Management of Acute Sinusitis

Inclusion Criteria: 1. 18-75 years old; AND are experiencing either: 2. "persistent" symptoms or signs compatible with ARS or sinus infection lasting for 1-21 days without any evidence of clinical improvement (Symptoms include facial pain or pressure, facial congestion or fullness, nasal obstruction, nasal discharge, no or reduced sense of smell, fever ≤39°C or 102°F, headache, bad smelling breath, fatigue, ear pain or pressure, and dental pain); OR 3. onset with worsening symptoms or signs characterized by the new onset of fever, headache, or increase in nasal discharge following a typical viral upper respiratory infection (URI) that lasted 5-6 days and were initially improving (''double-sickening''). Exclusion Criteria: * allergy or intolerance to penicillin * received systemic antibiotic therapy in the past 4 weeks * prior sinus surgery (cosmetic surgery, such as rhinoplasty, septal deviation, etc. are not exclusionary) * complications of sinusitis (facial edema (swelling), cellulitis), or orbital, meningeal or cerebral signs) * health care clinician determined IV (intravenous) antibiotics or hospital admission are required * pregnancy or breastfeeding * presence of a comorbidity or medication that may impair a patient's immune response as determined by a health care clinician * hospitalization in past 5 days * unable or unwilling to provide informed consent or comply with study protocol requirements * fever \>39°C or 102°F today * taking intranasal corticosteroids (INCS) regularly in the past two weeks and unwilling to stop its use while in the study; OR * previously enrolled or participated in the feasibility phase or this stage of study