You might have believed that an antibiotic a day can take the sinus infection away, but new research from Washington University in St. Louis suggests it's just not true.

Treating a common type of sinus infection called rhinosinusitus with the antibiotic amoxicillin won't reduce symptoms any faster than a placebo will, according to research published Tuesday in the Journal of the American Medical Association.

Over the course of three years, 166 adults were randomized to receive either a 10-day course of amoxicillin or a placebo. After three days, both groups showed the same level of  improvement, the study found.

The researchers also found no difference in the number of  missed workdays, the level of treatment satisfaction and whether patients  relapsed after treatment.  

Antibiotics are commonly used to all types of sinus infections, even though the evidence supporting their effectiveness is limited.

"I think patients feel awful, and they want something to feel better quickly," said Dr. Jane Garbutt, research associate professor of medicine and pediatrics at Washington University School of Medicine in St. Louis.  "And physicians want to treat the patient.  Everyone is between a rock and a hard place."

Antibiotics for sinusitis account for one  in five antibiotic adult prescriptions  in the United States.

But not all prescriptions for the medications are unnecessary. Some sinus infections are bacterial, and for them,  antibiotics might help. But according to Garbutt, in many cases it can be difficult for doctors to distinguish whether infections are viral or bacterial.

"We need more studies to try to identify what helps treat infections and factors that  help doctors identify which patients have the bacterial infection," said Garbutt.  

But for now, Garbutt suggests ditching the meds, because you're better off fighting off the infection on your own.