#1) Which happens when the effects of two or more drugs are canceled out or reduced by each other?
Answer: Drug-drug interactions occur when a drug interacts, or interferes, with another drug. This can alter the way one or both of the drugs act in the body, or cause unexpected side effects. However, interactions may also exist between drugs and foods (drug-food interactions), as well as drugs and medicinal plants or herbs. Synergistic is when the drug's effect is increased or antagonistic when the drug's effect is decreased.