One of the old, old arguments we’ve often had in the cannabis law reform movement is the question of whether cannabis is a “drug” or not. For a long time I was strongly of the opinion that it was, but over time I came to change my mind.

The term “a drug” is correctly applied to substances like THC, an active chemical which does interesting things in the brain and elsewhere. Cannabis of course contains THC, but cannabis isn’t just THC.

The cannabis “drug” effect isn’t the result of a the actions of a single drug, it’s a combination of at least two, some would argue many, substances we call drugs. Cannabis is more correctly described as containing a drug cocktail, rather than just “a drug” and different strains of the plant contain different proportions of these drugs and so have subtly – and sometimes not so subtly – different effects on the consumer.

So the cannabis plant produces a cocktail of active substances, one of which is THC which seems to have cancer curing / tumour killing properties.

But cannabis isn’t just this cocktail of active chemicals, it’s a plant and being a plant it contains a lot of non-drug plant type vegetation things that when burned give off smoke and soot which contain small particles less than 10 micron in size called PM10′s. PM10′s get into the lungs and cause cancer.

Not only that but the plant also contains other chemicals which are carcinogenic, which means they also cause cancer if you breath them in. Actually cannabis contains a similar amount of these nasties to tobacco.

Cannabis does contain this drug, THC, that may well be a cure for cancer and there is certainly a growing body of evidence to show that is the case, but it is a huge leap of logic from that to claim that cannabis cures cancer. What it probably means in practice is that because of the THC, smoking cannabis is less likely to cause cancer than it would do if it didn’t contain the THC.

Cannabis smoke, as I’ve already said, contains a lot of things that are known to cause cancer, so it’s reasonable to suppose these cancer causing effects are still at play in cannabis smoke. However, it is also very possible that the THC will act to inhibit, ie reduce or perhaps prevent – these carcinogens causing their damage which means cannabis is likely to be less carcinogenic than tobacco, which is what studies of cannabis using populations seem to show. How much less probably depends on several things, one of which might well be how strong the cannabis is; the higher the dose of THC compared to the amount of smoke you breath in the better the cancer inhibiting properties are likely to be.

The thing to understand in all this is two opposite things can be happening at the same time and it’s a matter of which effect wins out.

So does cannabis protect against the cancer tobacco causes?

The first and most obvious thing here is this balance of effects. The anti tumour effects of THC may win out against the carcinogenic nature of the rest of the cannabis smoke, but to ask them to take on the extra load of the tobacco smoke is really pushing your luck a bit. It’s stacking the odds in the wrong way by adding the amount of smoke to a given dose of THC. It may be true that cannabis provides some protection against tobacco induced cancers, but we’re a long way from it being a cure or a total protection.

But there is a potential nasty sting in the tail if the two are smoked together. THC has an effect which is normally good, a process called “vasodilation”, which means THC is a “bronchodilator”. A bronchodilator is a substance that dilates the bronchi and bronchioles, decreasing resistance in the respiratory airway and increasing airflow to the lungs. This is why cannabis can sometimes be effective against asthma, although again the smoke in cannabis means we have a push me pull you situation of bad and good things happening at the same time. This bronchodilator effect however means that if you smoke tobacco along with the cannabis, your lungs will absorb more of the toxic tobacco smoke than they would have done without the added cannabis; so it may well be the case that cannabis makes tobacco more dangerous if you smoke the two together.

So it is doubtful whether cannabis provides any protection against the cancer causing effects of tobacco if you mix the two as most cannabis users do, and it may actually make things worse. Anyone who tells you the cannabis will cure cancer as they puff away on a tobacco filled spliff is delusional frankly.

So it isn’t right to say “cannabis cures cancer”, to claim that is to greatly over egg the pudding. Such claims are not based on anything more than faith and give ammunition to the prohibitionists who use extreme claims like this against the law reform case. But it is possibly – indeed probably – true that smoking pure cannabis without tobacco is less likely to lead to cancer than smoking tobacco, if at all. Iindeed, this is what studies of pure cannabis smokers find, that is good news enough, there really is no need to over hype it.

The simple rule remains: The less smoke you breath in the better and this good news about cannabis smoking and cancer only applies to smoking pure cannabis. Vapeing cannabis instead of smoking it is very likely to be the best option of course.

Of course, that said, whole cannabis has other medicinal uses for cancer sufferers and many other ill people, non of the above detracts from that.  It may be that THC will prove to be an effective cancer cure in time, but that isn’t the same as saying smoking cannabis will prove to be that medicine.