Antibiotics are not needed for many sinus infections. Most sinus infections usually get better on their own without antibiotics. However, in some cases, antibiotics are needed. Talk to your doctor about the best treatment for your illness.Click to see full answer. Also know, what happens if you let a sinus infection go untreated? Rare cases can turn serious Antibiotics also can help ward off rare but potentially dangerous complications that arise when a sinus infection spreads to the eyes or brain, Dr. Sindwani says. This can lead to life-threatening conditions like meningitis or brain abscess, Dr. Sindwani says.Also Know, what is the best antibiotic for a sinus infection? Amoxicillin (Amoxil) is acceptable for uncomplicated acute sinus infections; however, many doctors prescribe amoxicillin-clavulanate (Augmentin) as the first-line antibiotic to treat a possible bacterial infection of the sinuses. Amoxicillin usually is effective against most of the strains of bacteria. Similarly, can you get rid of a sinus infection without antibiotics? Most cases of sinusitis are viral, and will clear up without antibiotics. Because sinusitis is normally viral, antibiotics should not be the first method for treatment. In fact, only 2-10% of sinus infections are bacterial.How long does it take for a sinus infection to go away with antibiotics?A viral sinus infection can develop into a bacterial infection, which typically lasts longer than 10 days. Once a bacterial sinus infection is diagnosed and treated, patients usually respond to antibiotics in 2-3 days and sinus infections resolve anywhere between 7-14 days after that.