ments of the population than recreational users. In the United States recreational marijuana use is most prevalent among 18 to 25 year olds and declines sharply after age 34. By contrast, reports on medical marijuana users indicate that most are over 35, as are typical consumers of herbal medicine and other alternative therapies. Most tend to suffer from chronic illnesses or pain that defy conventional treatments.

Medical marijuana advocates assert that patients usually obtain relief with smaller doses of the drug than would be used recreationally and that they rarely feel high when treating their symptoms with marijuana; however, no objective study has tested this claim. As discussed in detail in Chapter 3, marijuana and its constituent chemicals can produce both physical and psychological dependence. These risks must be taken into account if marijuana or cannabinoids are to be used as medicines.

Many effective medicines have side effects. The fact that marijuana affects the human body adversely does not preclude its use as a source of useful medicines. Many legitimate drugs—including opiates, chemotherapy agents, and steroids—have side effects ranging from the dangerous to the merely unpleasant. When used carefully, though, the benefits of these medications far outweigh their drawbacks. Patients may also develop tolerance, dependence, and withdrawal—conditions associated with marijuana use —when taking proper doses of several commonly prescribed medications. For example, the correct use of some prescription medicines for pain, anxiety, and even hypertension normally produces tolerance and some physiological dependence.

As researchers learn more about the chemicals present in marijuana and their effects on the body, it may be possible to identify beneficial compounds and separate them from harmful substances in the plant. Finding a rapid way to deliver cannabinoids to the body, other than smoking, could lessen some of marijuana's worst side effects. It may also be possible to reduce the adverse effects of specific cannabinoids through chemical modification, as previously noted.

Marijuana's effects vary with different delivery methods. Traditionally, medicinal marijuana has not been smoked but rather swallowed in the form of an extract or applied to the underside of the tongue in the form of an alcohol-based tincture. Although the lat-

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