What occurs when a person needs to increase the dosage of a drug to achieve the same effect as the initial dosage?

When a person needs to increase the dosage of a drug to achieve the same effect as the initial dosage, this phenomenon is known as drug tolerance. Drug tolerance occurs when the body becomes accustomed to a substance after prolonged use, requiring higher doses to produce the same pharmacological effect that was experienced initially. This can happen through various physiological adaptations, including changes in the body's metabolism of the drug or alterations in the brain's receptors.

Understanding drug tolerance is crucial in the context of substance use and treatment, as it can lead to higher consumption levels and an increased risk of adverse effects or dependence. In contrast, psychological dependence relates to an emotional or mental attachment to a substance, addiction encompasses both psychological and physical dependence with compulsive behaviors associated with drug use, and withdrawal refers to the physical and mental symptoms experienced when reducing or stopping drug intake after prolonged use.