Acute sinusitis is often treated with antibiotics, and possibly also a topical steroid.
However, a recent study found this common treatment to be no more effective than a placebo.
Commenters on the study have noted that there may be some patients for whom antibiotics might help, but there is no reliable way for a clinician to tell those patients from the others.
It is possible that this result is due to the greater level of resistance to antibiotics that has resulted from increased use of antibiotics over the last few years.