The physical sensation of a parched, sticky mouth following marijuana consumption is widely known as “cottonmouth.” This common, temporary side effect is medically termed xerostomia, which is the subjective feeling of oral dryness resulting from reduced saliva flow. Although often mild, the condition can be an uncomfortable distraction. Understanding the science behind this phenomenon reveals it is not simply due to dehydration or the drying effect of smoke, but rather a specific biochemical interaction within the body’s regulatory system.
The Endocannabinoid System
The endocannabinoid system (ECS) is a complex network of receptors, molecules, and enzymes that regulates internal balance throughout the human body. It influences processes like mood, appetite, sleep, pain sensation, and immune function. The ECS is composed of two primary protein receptors, Cannabinoid Receptor Type 1 (CB1) and Cannabinoid Receptor Type 2 (CB2), which are found in the brain, organs, and tissues.
The body naturally produces endocannabinoids, which bind to these receptors to modulate various activities. The active compounds in marijuana, known as phytocannabinoids—most notably delta-9-tetrahydrocannabinol (THC)—are molecularly similar to the body’s own endocannabinoids. This structural resemblance allows THC to hijack the ECS, binding to and activating the CB1 and CB2 receptors, thereby overriding natural regulatory signals.
The Mechanism of Reduced Saliva
The direct cause of xerostomia stems from the concentration of cannabinoid receptors within the major salivary glands, particularly the submandibular glands. These glands contain both CB1 and CB2 receptors. When THC enters the bloodstream, it travels to these glands, binds to the receptors, and interferes directly with the nervous system’s command to produce saliva.
Normal saliva production is stimulated by the parasympathetic nervous system through the release of the neurotransmitter acetylcholine. This chemical messenger signals the acinar cells within the salivary glands to secrete fluid. Research suggests that CB1 receptors are present on the ends of the cholinergic nerve fibers that innervate the glands.
When THC activates these CB1 receptors, it suppresses the release of acetylcholine from the nerve ending. By blocking this signal from reaching the gland cells, THC disables the “on” switch for saliva production. This localized interruption of the signaling pathway, rather than systemic dehydration, causes the dry sensation. The effect is proportional to the amount of THC consumed and persists until the concentration of THC in the gland tissue diminishes.
Managing and Preventing Dry Mouth
Since dry mouth is a pharmacological response, management focuses on stimulating the salivary glands and replacing lost moisture. Increasing water intake is effective, but sipping water frequently is better than large, occasional gulps. Keeping a drink nearby during consumption helps moisten the mouth and throat.
Chewing sugar-free gum or sucking on sugar-free lozenges or hard candies can physically stimulate saliva flow. The mechanical action of chewing triggers the natural salivary reflex, temporarily overriding the inhibitory effect of THC. Products containing xylitol are recommended because they stimulate saliva production without the risk of sugar-related dental issues.
For persistent dryness, over-the-counter saliva substitutes or moisturizing oral sprays are available. These products mimic the viscosity and moisture of natural saliva, providing a soothing coating. It is also advisable to avoid substances that are already dehydrating, such as alcohol and excessive caffeine, as they compound the feeling of dryness.