Cannabis preparations include resin-containing herbal flowers, which can be heated and delivered to the lungs via inhalation of smoke or vapor, and cannabis-based extracts, which include oral, oromucosal, rectal, and topically delivered preparations in the form of concentrates, suppositories, edibles, and salves.
Because cannabinoids are volatile, they will vaporize at a temperature below actual combustion, and can be inhaled without the generation of potentially harmful smoke. Cannabinoids are lipophilic and have nearly immediate onset of action when smoked or vaporized. Vaporization has the advantage of rapid onset of effect and easy dose titration, as the patient can slowly increase use to achieve desired therapeutic effect. Patients can be advised to pause briefly between inhalations to ascertain effectiveness of the medicine and to stop when maximum effect is achieved.
Oral ingestion of cannabis products has a delayed onset of action compared to inhalation and titration is more difficult. Maximum cannabinoid blood levels are reached up six hours post oral ingestion, with a half-life of 20-30 hours.
Exact dosages depend upon individual patient need and tolerance of side effects.

Cannabis medicines, both orally administered and inhaled, have been shown to have efficacy in randomized, double-blind, placebo-controlled trials (RCT) for a number of symptoms.
• Cancer pain: oral cannabis has analgesic efficacy to treat breakthrough cancer pain in patients who were started on a long-acting opioid. It was also well-tolerated.
• Chemotherapy induced nausea and vomiting: inhaled cannabis is an efficacious anti-emetic.
• Multiple sclerosis: inhaled cannabis improves numerous symptoms – spasticity, spasm frequency, insomnia, pain, and impaired mobility.
• AIDS wasting syndrome: inhaled cannabis in effective for appetite stimulation and weight gain.
• Neuropathic pain: inhaled cannabis showed significant analgesic efficacy for HIV sensory neuropathy and chronic, intractable neuropathic pain due to multiple etiologies.

Cannabis use can cause xerostomia, palpitations, flushing, nausea, confusion, anxiety, dysphoria, and acute psychosis. Cannabis ingestion raises the risk of a motor vehicle accident.

See reference for more information.

Adapted from Aggarwal SK, Blinderman CD. Christensen A. Cannabis for symptom control. Palliative Care Network of Wisconsin. Fast facts and concepts #279. Internet. Accessed on December 27, 2018.