The UK-based company is working on prescription medicines based on cannabis to treat a number of medical conditions.
Its stock soared as much as 43 percent to $65.97 after Morgan Stanley started coverage of the stock with an "overweight" rating and a price target of $103.
Cramer called Morgan's recommendation "timely" and "bold," predicting the stock will quickly reach the target.
"It's not a medical marijuana stock. They have a novel platform. It is an epilepsy company."
Cramer warned investors to stay away from other marijuana-related penny stocks. "Forget it! If you like cannabis, and I'm not necessarily speaking about 'liking' cannabis, it's GW Pharma."
—By CNBC's Alex Crippen. Follow him on Twitter