Ephedrine is a medication and stimulant.[1] It is often used to prevent low blood pressure during spinal anesthesia.[1] It has also been used for asthmanarcolepsy, and obesity but is not the preferred treatment.[1] It is of unclear benefit in nasal congestion.[1] It can be taken by mouth or by injection into a musclevein, or just under the skin.[1] Onset with intravenous use is fast, while injection into a muscle can take 20 minutes, and by mouth can take an hour for effect.[1] When given by injection it lasts about an hour and when taken by mouth it can last up to four hours