Storage, Administration, Side Effects, and Drug Interactions

This page outlines some considerations cannabis users should be aware of. I will talk about four topics: Storage, administration route, side effects, and drug interactions. There are plenty of gaps in the information, but I'll try to present as accurate a picture as I can.


The quality of your medical cannabis will decrease rapidly if you do not store it properly. You may have noticed a decrease in effectiveness and thought that some kind of tolerance to the drug was at work. This may be true too, but product degradation may be the major factor.

Temperature, oxygen, and light are all factors.  You want to minimize all 3 of these.

Where should it be stored?

The freezer portion of your refrigerator is the best place to store it. The lower temperature makes a big difference in shelf life. Only a days quantity should be kept out at a time.

In what type of container?

Although baggies are convenient when mobility is an issue, I strongly recommend jars. The ideal jar should be made with a dark coloured glass to block light. The lid should make a tight seal as well.  The tight seal is to keep out fresh oxygen.


Cannabis is best known as a drug that is smoked either rolled up as like a cigarette or in a pipe. This is probably the most common way cannabis is ingested. A less common method is that of eating cannabis in the form of "cannabis butter", a baked good, or sometimes, a tea. Each method has its advantages and disadvantages.

Another method I hope to see develop further is that of inhalers. Currently, the closest thing to an inhaler available is sold as a "vaporizer". Vaporizers heat the cannabis to the point where the oils containing the cannabinoids vaporize and become available for inhalation. The vegetative matter does not start to smolder, and so no smoke is produced. This probably has some positive health consequences for long term users. I strongly encourage the use of such products.

Improvements in this technology could focus on portability and convenience of use. Often medical users need small doses throughout the day and it would be useful for such a device to be "pocket sized". Battery power would be another step forward.

Convenience has several dimensions. One is discretion. An ideal puffer should utilize refillable cartridges that can hold enough cannabis for one dose each. Cartridges could then be carried and inserted into the puffer as needed. This would eliminate the need to open up a baggie of cannabis to fill the puffer. It also eliminates the need to dispose of the charred cannabis until the end of the day.

It might seem odd to want to go to all the trouble of developing a puffer to avoid smoking when all one has to do is administer the drug orally. There are two important problems with oral administration. Orally administered cannabis may have a role, but it will be limited.

The first problem has to do with dose titration. The drug action is delayed (over smoking for example), and so dosage adjustments for over and under medication are also delayed. Dosage titration is also hampered by unreliable absorption of cannabinoids (only 5 - 15 % of the THC). It is difficult to prescribe a dosage when it is unknown how much will actually make it into circulation.

The second problem has to do with first pass metabolism of cannabinoids when they are administered orally. First pass metabolism refers to chemical changes made by the liver on the cannabinoids before they are able to circulate through the rest of the bodies tissues. By eating cannabis all of the consumed matter is drained from the intestines via the hepatic vein directly through the liver.

Inhaling cannabinoids either as vapor or in smoke allows the drug to circulate to other tissues before the liver has a chance to alter it. This is important because delta-9 THC is modified to form 11-hydroxy THC, a cannabinoid with stronger psychotropic effects. When someone is trying to eliminate muscle spasms, psychedelic effects are side effects. This side effect is quite disturbing for many people and may be cause for discontinuing therapy inspite of success with the desired effects.

Side Effects

Cannabis has plenty of side effects the most obvious of which is the euphoria and perceptual changes. Side effects are, however, relative. If the purpose was to alter the mood and produce euphoria then the analgesic effects are the side effects.

The variety of effects produced by cannabis make it at once potentially widely useful, and replete with side effects. To compound this difficulty, most (if not all) of the effects attributed to cannabis are difficult to reproduce reliably. This may be due to a number of factors.

Bioavailability when smoked or eaten is variable. Absorption when eating cannabis varies from 5 to 15 % of delta-9 THC while absorption when smoking from 15 to 30%. The stomach's acid environment also degrades THC. Bioavailability (when eating cannabis) can vary with the kind of food eaten.

The important thing to remember as a medical user of cannabis is that side effects hitherto inexperienced could suddenly occur at the worst possible moment. Therefore, know the side effects, or make sure your doctor is aware of them if they are supervising your taking this drug.

Also, you may find your usual dose is not effective. This may signal a need to regularly increase the dose, but it may also mean absorption is poor at this point in time. For example, if you smoke the drug and you currently have a cold or flu, absorption may not return to normal values until the illness passes.

The following are some side effects reported by various researchers.Keep in mind that side effects are not always cause for concern.  There are two reasons for this.  The first is that the side effects reported in some studies involved unusual doses, low potency cannabis, and laboratory settings.  The other reason is that they may only be a concern for some people.  For example, if you unfamiliar with using mind-altering substances such as cannabis, the euphoria, or "high", can be quite disturbing.  Also, some side effects are evident only sometimes or in some people, or via some administration routes. Side effects are presented here not to alarm people, but to offer a guideline since in many cases you are acting as your own physician.  These are just effects to keep in mind.

  • euphoria
  • tachycardia (increased heart rate)
  • dizziness
  • muddled thinking
  • dry mouth
  • ataxia
  • paresthesia

Drug Interactions

When ever one uses a drug, whether the drug is a natural herb or a pharmaceutical preparation, drug interactions need to be considered. This section will probably see the most growth. There is a little information out there, but no independent verification.

Some studies indicate that CBD, the second most important chemical in cannabis, may inhibit the metabolism of other drugs. The one drug for which a study has been done (on rats) was phenobarbitol. Metabolism was reported to be inhibited by as much as 40%. Other drug metabolism may also be inhibited, but no studies have been done as yet.

Another point to keep in mind is the fact that CBD is suspected of being an anti-convulsant so if you are using phenobarbitol to control convulsions and then supplement this therapy with cannabis you are increasing the effectiveness of the phenobarbitol (through its decreased metabolism) and then adding another anti-convulsant on top of that.  Additionally, since at this time the CBD content of cannabis available in compassion clubs  is unknown and probably quite variable, it will be difficult to control the dosage.  If you suffer from seizures, I strongly encourage keeping your physician informed even if s/he does not agree with your course of action.

Although there is no consensus on the matter of drug metabolism inhibition, caution is strongly advised. If you are using any other medication, introduce cannabis slowly at first watching for increased side effects due to the original medication. Keep your doctor informed too.

By David Faren


Last Modified:Wednesday, 11-Sep-2002 15:39:10 PDT