The bioavailability of an IV medication is by definition 100%, unlike oral administration where medication may not be fully absorbed, or may be metabolized prior to entering the bloodstream. For some medications, there is virtually zero oral bioavailability. For this reason certain types of medications can only be given intravenously, as there is insufficient uptake by other routes of administration. The unpredictability of oral bioavailability in different people is also a reason for a medication to be administered IV - as with furosemide. Oral medications also may be less desirable if a person is nauseous, vomiting, or has severe diarrhea - as these may prevent the medicine from being fully absorbed from the gastrointestinal tract. In these cases, a medication may be given IV only until the patient can tolerate an oral form of the medication. The switch from IV to oral administration is usually performed as soon as viable, as there is generally cost and time savings over IV administration. Whether a medication can be potentially switched to an oral form is sometimes considered when choosing appropriate antibiotic therapy for use in a hospital setting, as a person is unlikely to be discharged if they are still requiring IV therapy.