Although the vast therapeutic potential of cannabis is certainly exciting, understanding how to dose medical cannabis can be challenging.

Focus on THC

Up to now, most of the attention in dose determination has been focused on the psychoactive effects of Tetrahydrocannabinol (THC). However, it is now evident that the other (non-psychoactive) cannabinoids may be of equal or greater therapeutic importance, depending on the ailment to be treated.

With that said, since the psychoactive effects of THC remain the main determinant of normal or “altered” daily functioning for most people, it is wise to continue to refer to the THC content of a strain when discussing the dosing of cannabis as a medicine. After all, most individuals would prefer not to be impaired while medicating during their daily routines.

Some patients will need a high percentage of THC’s psychoactive effect, while others will need a low percentage of THC’s psychoactive effect. Remember, THC does possess a number of powerful therapeutic properties.

Each patient has to determine how much THC (or any of the other cannabinoids) they need in their system based on their individual tolerances, their daily routine, and what therapeutic effect they are seeking.

How You Consume Cannabis

When dosing, you must consider how you are consuming it (smoking, vaporizing, eating, absorbing through the skin, etc.). For example, eating cooked edibles may be 3-5 times more psychoactive than inhaled cannabis.

Be aware that eating cannabis will provide a more potent and longer lasting effect than what most smokers of cannabis are used to. When THC is digested and metabolized in the liver, it is converted into 11-Hydroxy THC, which is more psychoactive than Delta-9 THC. Too much of this can cause THC toxicity which can result in dysphoria (this will pass with time and is not lethal).

With all of this in mind, there are a few rules-of-thumb to keep in mind when determining how cannabis is currently dosed as a medicine.


1. To convert cannabinoid percentages into milligrams:

Move the decimal point one digit over to the right. That is, for each gram of flower or concentrate, take the percentage of THC or any other cannabinoid and move the decimal point over. Here are a few examples:

The above conversion rule-of-thumb may be applied to terpenoids as well.

2. Normal Adult Dosage of THC:

Patients should consider both their previous experiences with cannabis, as well as their frequency of use when deciding their dosage, as tolerance can greatly affect the strength of the medication.

3. Converting THCA Content:

In an unheated product that lists THCA and THC, multiply the THCA milligrams by 0.61 and add the milligrams of THC to get the total amount of THC.

4. Cannabis Absorption:

Under ideal conditions, only about 63% or less of the cannabinoids will be absorbed when smoked. Multiplying the milligrams of THC by 0.63 will result in a more accurate calculation of dose.

5. Incremental Dosage:

When dosing edibles, it is recommended that you start with a small amount to avoid THC toxicity. Start with the beginners dosage, wait two hours to see how the medicine affects you, then increase the dose gradually as needed. Keeping a personal journal will help in determining your proper individual need.