When home remedies do not work for treating sinusitis, the antibiotic that is usually prescribed is amoxicillin, reports WebMD. It is efficient in most cases and has a small number of side effects. Trimethoprim-sulfamethoxazole may be a second choice if a patient is allergic or resistant to amoxicillin.
Other antibiotics that may be prescribed include doxycycline, levofloxacin and moxifloxacin, says Everyday Health. While the exact duration of antibiotic use is unclear, it is recommended that adult treatment last for five to seven days and 10 to 14 for children. Antibiotics destroy current bacteria and prevent the growth of fresh bacteria, notes WebMD.