I, personally and with my kids, have had no luck with amoxicillin for sinus infections. For one, amoxicillin works best on aerobic bacteria and sinus infections are usually caused by anaerobic bacterias. The New Sinus Infection Treatment You Haven't Heard About Yet Works Better Than Antibiotics - Duration: 5:15. Life Well Lived 176,617 views I’m a lifelong chronic and acute sinus infection patient. I have carefully observed my symptoms and patterns over 30+ years and can tell the difference between actually getting better and double worsening, between a fleeting viral sinus infection and a bacterial sinus infection settling in for a long spell. Do not take amoxicillin if you are allergic to penicillin drugs or other antibiotics. Talk to your doctor about alternative antibiotic treatments to treat the sinus infection. Doctors give trusted answers on uses, effects, side-effects, and cautions: Dr. Cirino on how long can you take amoxicillin: on the condition, some would take it for years, but if you need it for long, better run it by tour doctor, best wishes. Doctors help recognize, prevent, and treat allergies: Dr. Ferguson on how long should i take amoxicillin for sinus infection: If you're asking it likely means you have likely self diagnosed & are using some left over med from another illness or other source. This is not a good idea.You could be right, or wrong.Your problem may not require antibiotics & clear on it's own. Timing & duration of. This is the dosing information for amoxicillin which would apply to a sinus infection. Adults, teenagers, and children weighing more than 40 kilograms (kg) (88 pounds) —250 milligrams (mg) to 500 mg every eight hours or 500 mgto 875 mg every twelve hours, depending on the type and severity of the infection. Due to the severity and longevity of the sinus infection, an individual may have to take larger doses of amoxicillin. The typical sinus infection requires around 1,500 mg daily of amoxicillin, but in more severe instances a person may need to take 2,000 mg to 2,500 mg daily to ward off the infection. Read on to find out how sinus infections are diagnosed, when your doctor may prescribe antibiotics, and how long it will take antibiotics to take effect. Diagnosing Sinus Infections Symptoms of a sinus infection may include headache, facial pressure, and severe nasal congestion. Amoxicillin Dosage for Sinus Infection. According to the official literature, the dosage of amoxicillin for adults can range from 250 mg. to 1 gm three times a day, depending on the severity of the infection.