There's no shortage of misinformation on the internet, and medical marijuana isn't immune to it. That's why a California-based doctor is warning patients to be wary of webpages claiming that cannabis can cure cancer.

"We know that a component in cannabis—CBD—might be useful in treating cancer," Dr. Joseph A. Califano III - Director of the Head and Neck Cancer Center at UC San Diego - told the LA Times. "But we don’t know if marijuana can stop or cure it. In some cases, cannabis might make things worse. It’s going to take time to find out."

Califano also compared today's perceptions of medical marijuana to attitudes toward cigarettes in the 40s.

"What’s happening right now with marijuana reminds me of tobacco at the end of World War II. There was an explosion in its use, but little science to let people know what we were dealing with."

And there are a number of reasons for this. First, it can be hard to slow the spread of misinformation once it starts spreading because people are free to say whatever they want - whether it's true or not. Additionally, cannabis research is difficult to conduct in the US. That means we don't know as much about it as we might like—especially considering it is increasingly legal across the country.

But, there are health conditions that cannabis has been shown to be an effective treatment for. Things like epilepsy and chronic pain, to name two examples.

And as long as many physicians aren't comfortable recommending medical marijuana, and research efforts continue to be stalled getting good advice will probably remain difficult.

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