Inhaling cannabis is the most common method of consumption, has the most immediate effects, the shortest duration, and can involve either smoking or vaporizing cannabis buds or extracts. Combusting cannabis buds can be done in a joint, pipe, or with additional water filtration in a bong or bubbler. While there have been numerous attempts to study a supposed connection, there is no correlation between smoking cannabis and cancers of the pulmonary system. It is fair to say there is additional irritation of the lungs that should be avoided if a patient has respiratory issues. Heating cannabis flower or extract at a lower temperature will vaporize the water content and a range of phytochemicals without combusting the carbon and creating irritants. Concentrated oils have had the carbon content removed, so you can directly consume them with a “dab rig” and inhale vaporized cannabinoids. For a more metered dose, vaporizer cartridges use a disposable heating element that is powered by a mobile battery.
Consuming cannabis orally has more potent effects due to a different metabolic route through the liver that produces 11-hydroxy THC, although it takes longer to feel the effects. Keep in mind that your body will absorb the contents of a liquid faster than a solid edible such as a brownie. As such, you will experience the effects sooner (45 minutes vs 1-2 hours), the peak effect will be more intense, and the effect will dissipate quicker (4 - 8 hours). The cannabinoids need to be activated into their active metabolites (decarboxylated), which can be done by applying low heat. This will convert the acid forms of the cannabinoids (THCA, CBDA) into the biologically active metabolites THC and CBD. While brownies have become emblematic of edible cannabis, you can consume it as a tincture, capsule, condiment, beverage, tea, or can simply eat a decarboxylated quantity of bud or oil.
The topical application of cannabinoid compounds can provide localized relief without psychoactive effects due to the cannabinoid receptors found in the skin. As with more traditional methods, different cannabinoids will interact with the receptors differently resulting in different therapeutic effects. When combined with other phytochemicals, this can result in relieved pain, reduced muscle inflammation/tenderness, soothed swelling, mitigated skin damage, and even alleviated migraine symptoms. You can directly apply extracts such as RSO and infused coconut oil to your skin, but they are typically combined with other compounds to increase efficacy. These options include lotions, bath salts, balms, oils, and sprays.
There are several additional routes of administration that are possible but are not as prevalent. Anal suppositories are considered by some to be the most medically efficacious delivery mechanism, as it delivers cannabinoids directly to the bloodstream without being metabolised by the liver. Transdermal delivery (predominately via patch) also delivers cannabinoids directly to the bloodstream, but can cause irritation to the areas where the patch is applied. There is the potential of intranasal delivery, asthma style inhalers, nebulized, and even catheterized medication.