Which of the following is a common side effect associated with cannabis use?

Dry mouth, often referred to as "cottonmouth," is a well-documented side effect associated with cannabis use. This occurs due to the effects of THC (tetrahydrocannabinol), the primary psychoactive compound in cannabis, which interacts with the salivary glands, reducing saliva production. As a result, individuals may experience a feeling of dryness in the mouth after consuming cannabis, which is a common and recognizable symptom among users.

In contrast, hallucinations and an increased heart rate can occur but are generally less common side effects and can depend on the dosage and individual response to the drug. A decreased pulse rate is not a typical side effect associated with cannabis; rather, cannabis is more likely to lead to an increased heart rate among users due to its stimulant effects on the central nervous system. Thus, dry mouth stands out as a characteristic and easily observed side effect of cannabis use.