Weed is famous for its ability to relieve nausea, but it can have the opposite effect in people who smoke a lot of it. The little-known condition, called cannabinoid hyperemesis syndrome (CHS), involves bouts of extreme nausea, vomiting, and stomach pain, and can be temporarily relieved by a hot shower.
Source: LifeHacker – Too Much Weed Can Cause Nausea and Vomiting