Contrary to what one might think, a lot of people who are truly using marijuana for medical conditions don't really want to spend all their time getting high. Fortunately, there are ways to take advantage of cannabis that avoid the traditional high. However, until clinical trials are done, people will still have to experiment on themselves in order to determine what works best for their specific condition.
Of all the cannbinoids contained in marijuana, it is only the cannabinoid THC that is strongly psychoactive. The second most abundant cannabinoid in marijuana, CBD, is non-psychoactive even though with certain doses it might make you either more alert (low dose) or sleepier (high dose). Furthermore, CBD appears to interfere with the ability of THC to bind with the CB1 receptors in the brain. In other words, the more CBD in your product, the less high you will be, and, additionally, many of the health benefits of cannabis have been associated in particular with cannabidiol, i.e. CBD. Thus, at many medical marijuana dispensaries you can now find strains that are higher in CBD than THC, and you can also find tinctures that are high in CBD and have little or no mind-altering effect.
Raw, unheated marijuana actually contains very little THC. Instead, it contains THC and CBD in their acid forms, THCa and CBDa. These acid forms are also non-psychoactive, and THC is produced only when the cannabis is heated. Furthermore, raw cannabis has strong analgesic and anti-inflammatory properties. Thus, by using products that are high in CBD or by using raw cannabis, you can get medicinal benefits without getting high or altering your state of consciousness any more than a Benadryl would. Note, though, that if your cannabis is old, then some of the THCa may have converted to THC simply by being on the shelf so long, and, in this case, the THC is metabolized by the liver into 11-hydroxy-delta-9-THC which produces both a different and longer lasting altered state than regular THC. Thus, if you do get a little uncomfortably high from your raw cannabis, find something fresher!