New mood-altering substances are continually emerging in our communities. While it is important to become aware of the specific effects and potential harms linked to emerging drugs, it is helpful to understand principles of substance-use risk that apply to all substances, legal and illegal.

All substance use involves a measure of risk
While those using mood-altering drugs always seek some sort of benefit, non-medical substance use almost always poses some risks. Risk, in this sense, is an estimate of how likely it is that harm will occur as a result of using a substance. Risk from non-medical substance use can range from very low to very high, but it is important to know that even at low levels of risk (for example, when a person is experimenting for the first time), harms may occur.

The greater the amount used on an occasion, the greater the level of risk
Using any substance to the point of intoxication, often termed binge use, usually results in disorientation, lack of judgment, and loss of motor coordination. This kind of use greatly increases the likelihood of injury due to accidents or violence. Due to their relative lack of experience, young people are particularly at risk. Understanding the amount used is difficult with illegal substances that have unknown purity, hence the risk of overdose.

Combining substances is very risky
There are increased risks involved in taking more than one drug at a time. The combined effects of two drugs can be greater than expected (i.e., it may be that 1+1=3); often the result is unpredictable. For example, authorities are increasingly concerned with the combined effects of cannabis and alcohol when driving.

The interaction of person, drug, and setting greatly influences the level of risk
The interaction of the person, the drug, and the setting determines the effects and harms linked to use of a substance.

The person’s physical traits, such as weight, gender, metabolism, and state of health, can all play a role in determining risk levels. A person’s state of mind—their mood and expectations—will help to determine the experience and the level of risk involved in a drug-using situation (for example, risk increases when a person drinks in an angry state or to cope with sadness, rather than to enhance an enjoyable situation).

The way the drug is prepared (i.e., weak vs. strong dosage) will help to determine risk. For example, the strength of cannabis used in Canada is now generally much greater than was the case 20 years ago, and risks are increased accordingly. The manner of use (i.e., swallowing, sniffing, inhaling, or injecting) has a large bearing on the level of risk involved. Swallowing tends to reduce the peak “high” and lengthen the period of intoxication. On the other hand, sniffing, inhaling, and injecting all result in a rapid and quite possibly, disorienting drug effect that may be dangerous. Injection is particularly dangerous because of the risk of contracting an infection, such as HIV or hepatitis C, from shared needles.

Substances usually affect motor coordination, judgment and intellectual functioning in various ways. For that reason, there are certain settings or contexts for drug use that always pose a high risk for harm and should always be avoided: before driving a car, boat, ATV, or snowmobile, or using other machinery; before studying or working; before sports or other physical activity; before sexual activity; when pregnant; when using medication or other substances; and when sick.

Risk increases with frequency and duration of use
Beyond the level of risk associated with a single, drug-using situation, frequency and duration of use is also a major factor. The more frequently larger amounts are used over a lengthy period of time, the greater the likelihood of a dependency. Dependence, characterized by an inability to control use even in the face of negative consequences, can occur with any mood-altering substance, regardless of whether it is capable of producing physical dependence or only psychological dependence. Some persons can stop dependent use of a substance on their own, but most benefit from help from specialized treatment services or a self-help group.