Why Does Weed Make Your Mouth Dry?

Dry mouth isn’t an exclusive phenomenon of marijuana consumption alone. It has been linked to auto-immune disorders (Sjogren’s syndrome), tobacco use, and certain drugs and over the counter medications (i.e. decongestants and antihistamines). It was previously thought that simply inhaling marijuana smoke was the main culprit to getting a dry mouth, as it often is when smoking cigarettes, but recent research has suggested this is may not be the case. Marijuana appears to cause this annoying side effect simply due to the very nature of its mechanism of action alone, as dry mouth is experienced by the user whether they smoke, vape, drink, or eat marijuana.

Marijuana contains cannabinoids which are chemical compounds, that when inhaled or ingested, provide the desired effects marijuana users seek; the most common cannabinoid being THC (tetrahydrocannabinol). Since the 1980s, researchers have known that the human body contains specialized receptors specifically designed for cannabinoids; part of the endocannabinoid system. There are currently two known types of cannabinoid receptors in the human body, CB_1, and CB₂. These receptors are located all throughout the body, from the brain, lungs, kidneys and even our immune system, and when cannabinoids are released into the system, they lock into these receptors initiating their effects.

A group of researchers from the University of Buenos Aires has provided some context on the issue of dry mouth associated with marijuana use. They discovered that the submandibular glands – a pair of glands located beneath the floor of the mouth and responsible for producing about 70 percent of our saliva, have both types of cannabinoid receptors on them. They go on to say that when cannabinoids, such as THC, bind to these gland receptors, they stop receiving messages from the parasympathetic nervous system – involved in the sending signals to produce saliva.

Interestingly, however, this local inhibition of the salivary gland wasn’t the only effect caused by cannabinoids.  It was also discovered that receptors in the brain, also involved in transmitting salvia producing signals, appeared to be inhibited as well; creating two pathways cannabinoids can cause dry mouths.

While the reasoning behind why cannabinoids have this effect on our saliva production is not entirely sure, it may play a role as simply being a side effect of augmenting our endocannabinoid system, which has been postulated to play a part in hunger and appetite.

While the effect of having decreased amounts of saliva may be uncomfortable, it is by no means harmful in any way; but simply a temporary annoyance. It is recommended to have water, gum, or some sort of beverage on hand to help circumvent the symptom of dry mouth due to cannabis.