Why do older adults often need lower doses of medicines than younger adults?

Older adults often require lower doses of medication primarily because their bodies process and eliminate drugs differently than those of younger adults.1

As individuals age, they experience a natural decline in kidney and liver function. Because the liver is responsible for the metabolism of many drugs and the kidneys are essential for their excretion, reduced function in these organs can cause medications to remain in the system longer, leading to higher concentrations and an increased risk of side effects.12

Additionally, older adults often have less physiological reserve due to age-related changes, such as decreased organ mass and reduced blood flow to vital organs. Because they may also be managing multiple health conditions with various medications, they are more susceptible to adverse drug interactions. Consequently, the standard of care in therapeutics is to prescribe the lowest effective dose to ensure safety and minimize the risk of toxicity.12