Because cannabinoid receptors, unlike opioid receptors, are not located in the brainstem areas controlling respiration, lethal overdoses from Cannabis and cannabinoids do not occur.[1,2,3,4] However, cannabinoid receptors are present in other tissues throughout the body, not just in the central nervous system, and adverse effects include tachycardia, hypotension, conjunctival injection, bronchodilation, muscle relaxation, and decreased gastrointestinal motility.
Using tobacco is the leading cause of oral cancer.
All forms of tobacco, including cigarettes, pipes, cigars, and chewing (smokeless) tobacco, can cause oral cancer. For cigarette smokers, the risk of oral cancer increases with the number of cigarettes smoked per day. Tobacco use is most likely to cause oral cancer in the floor of the mouth, but also causes cancer in other parts of mouth and throat.
The risk of oral cancer is greater in people who use both tobacco and alcohol than it is in people who use only tobacco or only alcohol.
Tobacco users who have had oral cancer may develop second cancers in the oral cavity or nearby areas. These areas include the nose, throat, vocal cords, esophagus, and trachea (windpipe). This is because the oral cavity and nearby areas have been exposed to the harmful substances in tobacco, and new cancers may form over time.
Using alcohol is a major risk factor for oral cancer.
The risk of oral cancer increases with the number of alcoholic drinks consumed per day. The risk of oral cancer is about twice as high in people who have 3 to 4 alcoholic drinks per day compared to those who don't drink alcohol.
The risk of oral cancer is higher in people who use both alcohol and tobacco than it is in people who use only alcohol or only tobacco.
Being infected with a certain type of HPV virus, especially HPV type 16, increases the risk of oral cancer. HPV infection is spread mainly through sexual contact. People who have many oral sex partners have a higher risk of HPV infection. The number of cases of oral cancer caused by HPV infection is small but increasing.