Daily Amounts Fact Sheet ~ Health Canada

When considering the use of cannabis for medical purposes, it is understandable that patients and healthcare practitioners may have questions regarding dosage and daily amounts of cannabis for specific medical conditions. The following information has been prepared to provide patients and healthcare practitioners with information related to daily amounts and dosing. The information provided in this fact sheet should be used in combination with the Consumer Information Insert that accompanies each shipment of marijuana for medical purposes.

Onset, Peak, and Duration of Effects

With inhalation (smoking, vaporizing), effects may be felt within a few minutes of dosing and will generally peak within 30 mins.^{Footnote 1} Acute effects generally last between 2 and 4 hours but may be longer (e.g. 24 hours).^{Footnote 2}

With oral ingestion (e.g. oils, foods, capsules), acute effects may begin to be felt as quickly as 30 mins and as late as 3 or 4 hours after administration.^{Footnote 3} This variability in timing depends on a number of factors (e.g. amount of food in stomach). It is prudent to wait a minimum of 2 hours between administration of single doses of oral products to avoid possible overdosing.^{Footnote 4} Acute effects generally peak between 3 and 4 hours after dosing and can last up to 8 hours or longer e.g. 12–24 hours).^{Footnote 5}

With topical application, it is not known how long it takes for potential therapeutic effects to appear, nor how long they last. There have been reports of hypersensitivity reactions (e.g. rashes, itching) when skin has come into contact with cannabis.^{Footnote 6}

Dosing Amounts

Information obtained from a limited number of small and short-term clinical studies of cannabis for medical purposes indicate the daily doses of smoked or vapourized dried cannabis ranged from as little as 75 mg of dried cannabis 9.4% THC by weight) (i.e. 7 mg THC/day) to a maximum of 3.2 grams of dried cannabis (1–8% THC by weight; i.e. 32 to 256 mg THC).^{Footnote 7},^{Footnote 8}

Doses of THC as low as 2.5–3 mg of THC (and even lower) are associated with a therapeutic benefit and minimal psychoactivity. ^{Footnote 9},^{Footnote 10},^{Footnote 11}

Various surveys published in the peer-reviewed scientific and medical literature have suggested that the majority of people using smoked or orally ingested cannabis for medical purposes reported using between 10–20 grams of cannabis per week, or approximately 1–3 grams of dried cannabis per day. ^{Footnote 12}

One study reported the average daily dose of dried cannabis (of various potencies) used by patients in the Netherlands’ Medical Cannabis program was 0.68 grams per day (range: 0.65 –0.82 grams per day).^{Footnote 13}

Another study suggests that regardless of route of administration (inhalation vs. oral), individuals reporting use of cannabis for medical purposes reported consuming equivalent amounts of cannabis per day and that amount averaged at around 3 grams per day. ^{Footnote 14}

• For smoking and vapourizing, the median reported dose was 1.5–2.0 grams per day respectively.
• For edibles, the median reported dose was 1.5 grams per day.
• For teas, the median reported dose was 1.5 grams per day.

There is no information available on dosing amounts for topically applied cannabis products (e.g. ointments, creams, lotions, oils, balms, salves), however one study suggests approximately 5% of individuals who use marijuana for medical purposes use such products.^{Footnote 15}

There is no information available on dosing amounts for fresh marijuana.

In the absence of any clinical studies conducted with cannabis products, such as oils that are ingested orally, the following information has been provided as a reference to give some potential guidance around dosing.

For products such as oils that are ingested orally

• The available clinical evidence for Marinol^®, an orally administered capsule that has received market authorization and that contains synthetic THC dissolved in sesame oil, indicates a dosing range from as low as 2.5 mg THC per day to a maximum dose of 210 mg THC per day.^{Footnote 16},^{Footnote 17},^{Footnote 18} Doses lower than 2.5 mg (e.g. 1 mg) THC may further avoid incidence and risks of adverse effects.
• Average dose of Marinol^® is 20 mg THC per day.^{Footnote 19}
• Maximal recommended daily oral dose of Marinol^® is 40 mg per day.^{Footnote 20}, ^{Footnote 21}
• Preliminary information from an open-label clinical trial with Epidiolex^® (an orally administered oil extract containing mainly cannabidiol (CBD) for treatment of certain types of childhood epilepsy not responsive to conventional treatment), suggests a daily dosing range between 5 and 20 mg/kg CBD.^{Footnote 22} However, further clinical studies are required to substantiate this information.