Empiric therapy is a medical term referring to the initiation of treatment prior to determination of a firm diagnosis. It is most often used when antibiotics are given to a person before the specific microorganism causing an infection is known. Examples of this include antibiotics given for pneumonia and urinary tract infections.
Empiric antibiotics are typically broad-spectrum, in that they treat a wide variety of possible microorganisms. When more information is known (as from a blood culture), treatment may be changed to a different antibiotic which more specifically targets the microorganism known to be causing disease.