If you are talking about marijuana used as an anti-nausea agent, then it could replace such drugs as promethazine, prochlorperazine, ondansetron, or granisetron. These drugs are all available in injectable forms, which marijuana is not, to my knowledge. For severely ill patients, an injectable form may be the only choice. I am not qualified to compare the safety of these drugs to marijuana. I believe the choice of which to use would depend on the patient's condition and his preference. I believe that medical marijuana has legitimate uses and should be available to those who need it.