Drug tolerance means that with time the body became tolerant and "gets used" to a of the drug so it requires a higher dosage of the drug to achieve the same effects as previously. The statement that tolerance to a particular drug might also increase to other drugs in the same class is true. The term used to describe this phenomenon is cross-tolerance. Cross -tolerance occurs when a person develops a physical tolerance to a specific substance, which then translates to tolerance of other drugs.
