TRUE.
What is tolerance? Tolerance means that to get the same high, the person needs to drink more alcohol or take more drugs. Over time, with regular use, a user needs more and more of the drug to get the desired effect. Increased tolerance means an increased risk for overdose, for two reasons. First, every drug has a main effect (the effect the user wants) and side effects (effects that the user does not want). Tolerance does not develop evenly to all effects of a drug. For example, barbiturate users develop tolerance to the desired mood-altering effect of the drug faster than they do to the side effect of depressing breathing. When the user increases the dose to get the desired effect, they risk taking enough to cause them to stop breathing, which of course would cause death. Second, if a user has not used the drug for a while, tolerance will decrease. Tolerance to any drug decreases with non-use. After a period of not using a drug, the dose the user had previously used may now be enough to cause a fatal overdose. Heroin is a good example of a drug for which tolerance can drop very quickly, and many people die every year from heroin overdose.
