Several methods of dosing and routes of administration of cannabis are available. Smoking and vaping; edibles oils or tinctures (oral); creams or lotions; intranasal, intravaginal and intrarectal preparations can be found in retail shops. There are no intramuscular or sub-cutaneous preparations available so far. In general, smoking or vaping produce the most rapid effects. More rapid rates of rise of molecules in the brain produce greater psychotropic effects. It is not clear if these psychotropic effects add to the efficacy of treatment, but some find them aversive. Smoking also produces higher peak dose effects and a more rapid peak blood levels. Smoking, vaping, and intra-nasal preparations bypass the liver, and thus result in fewer “”first pass effects””, meaning less metabolism and production of fewer metabolites. Some cannabinoid metabolites are more active than the natural plant derived molecules. Thus, eating cannabis may produce more active metabolites than smoking or vaping. This may result in a different psychotropic and therapeutic profile with the same material. It may be best to try both methods when trying to determine which works best for your symptoms. Smoking produces more harmful effects on the lung. Vaping is also likely toxic to the lung, but the side effects of vaping are relatively unstudied. Another factor which affects both the side effects and the efficacy (positive benefits) of the plant material is if it is processed hot or cold. Hot processing cleaves carboxyl groups (acids) off of many of the terpenes, particularly THC and CBD, two of the molecules getting the most current press. Both of the carboxylated forms, CBDA and THCA have a different pharmacological profile than their decarboxylated forms. Heating through cooking, smoking, and vaping cannabis all create more of the decarboxylated forms, and thus will have different effects than the same material that was cold processed. Topicals (creams and lotions) have limited local effects because they are not well absorbed through the skin into the bloodstream. When using cannabis for medical conditions remember to stay with one preparation, at a time as you increase your dose.