Ephedrine is a central nervous system (CNS) stimulant that is often used to prevent low blood pressure during anesthesia.[6] It has also been used for asthma, narcolepsy, and obesity but is not the preferred treatment.[6] It is of unclear benefit in nasal congestion.[6] It can be taken by mouth or by injection into a muscle, vein, or just under the skin.[6] Onset with intravenous use is fast, while injection into a muscle can take 20 minutes, and by mouth can take an hour for effect.[6] When given by injection it lasts about an hour and when taken by mouth it can last up to four hours.[6]

Common side effects include trouble sleeping, anxiety, headache, hallucinations, high blood pressure, fast heart rate, loss of appetite, and inability to urinate.[6] Serious side effects include stroke and heart attack.[6] While likely safe in pregnancy, its use in this population is poorly studied.[7][8] Use during breastfeeding is not recommended.[8] Ephedrine works by increasing the activity of the α and β adrenergic receptors.[6]

Ephedrine was first isolated in 1885 and came into commercial use in 1926.[9][10] It is on the World Health Organization's List of Essential Medicines.[11] It is available as a generic medication.[6] It can normally be found in plants of the Ephedra genus.[6] Dietary supplements containing ephedrine are illegal in the United States,[6] with the exception of those used in traditional Chinese medicine, where its presence is noted by má huáng.[6]