Marijuana: Uncertain Medicine In many states, marijuana is now considered medicine. But it does not arrive at the dispensary in standardized formulations and doses, and its effects on an individual can be difficult to predict. For starters, there is the way you consume the drug. When smoked, cannabis takes effect within minutes. When eaten, it can take over an hour for the effects to set in, and they may last much longer. Now, marijuana businesses and users commonly distinguish between two types of cannabis plants and hybrids of the two: cannabis sativa and cannabis indica. Physically the plants are quite different. Cannabis sativa has thin, lanky stems and narrow leaves. Cannabis indica is a stocky, smaller plant with stubby leaves. And many users report that the plants deliver distinct highs as well. Sativa strains are said to produce a high that is energetic, euphoric and cerebral. Indica delivers what some users describe as a “body buzz,” which may help medical patients manage pain. Scientists are not quite sure of what to make of this distinction and the anecdotal evidence that supports it. After all, research into cannabis is still in its infancy, in part because federal restrictions have held it back for decades. Experts say that THC, the psychoactive compound in marijuana, induces the high. But THC alone could not explain the difference between a stimulating and a sedative high. One hypothesis is that the varying effects result from the interaction of THC with other chemical compounds in the plant. This is known as the “entourage effect.” Of course, each user’s genetic profile also influences her reaction to cannabis and THC. In that way, marijuana is no different than two other substances Americans use every day: caffeine and alcohol.