The most common medication problem in older adults is adverse drug events, meaning harmful or unintended effects caused by medications. These events account for up to 30% of hospital admissions in people over 65, making them one of the leading causes of preventable harm in this age group. The problem stems from a combination of factors: taking too many medications at once, age-related changes in how the body processes drugs, and gaps in communication between providers.
Why Older Adults Are Vulnerable to Drug Harm
As you age, your body handles medications differently. Two organs do most of the work processing and eliminating drugs: the liver and the kidneys. Both decline with age in ways that directly affect how long a drug stays in your system and how intensely it acts.
Kidney filtration rate drops progressively over the decades, which slows the clearance of many common medications including anti-inflammatory drugs, certain heart medications, and antibiotics. The liver shrinks in size and receives less blood flow, which means drugs that would normally be partially broken down on their first pass through the liver instead enter the bloodstream at higher concentrations. A dose that works fine for a 40-year-old can effectively become an overdose in a 75-year-old, even though the prescription looks identical on paper.
Body composition shifts matter too. Older adults tend to carry more fat relative to lean tissue, which increases the volume of distribution for fat-soluble drugs. In practical terms, these medications get stored in body fat and released slowly, extending their effects well beyond what’s expected.
Polypharmacy: The Multiplier Effect
Polypharmacy, defined as taking five or more medications regularly, is extremely common among older adults managing multiple chronic conditions. Each additional drug increases the chance of an interaction with another drug, a side effect that mimics a new symptom, or a prescribing cascade where one medication’s side effect gets treated with yet another medication.
The drug classes most frequently responsible for emergency department visits in older adults are antibiotics and other anti-infective agents (15.9% of adverse events), blood thinners like anticoagulants (14.2%), cancer drugs (9.6%), and opioid pain medications (7.3%). Blood thinners and opioids cause harm out of proportion to how often they’re prescribed, making them especially high-risk in this population.
The Beers Criteria: Medications to Watch
The American Geriatrics Society maintains a list called the Beers Criteria, updated most recently in 2023, which flags medications that are potentially inappropriate for older adults. The latest update strengthened warnings on several widely used drug classes. Benzodiazepines (commonly prescribed for anxiety and sleep) now carry stronger language about risks in people with dementia or delirium, with encouragement to try non-drug approaches first. All sulfonylureas, a class of diabetes medication, are now flagged rather than just the long-acting versions, due to risks that go beyond blood sugar drops to include cardiovascular events and stroke.
Proton pump inhibitors, the popular heartburn drugs many people take for years, had pneumonia and gastrointestinal cancers added to their risk profile. Rivaroxaban, a newer blood thinner, was upgraded from “use with caution” to “avoid” because of higher bleeding risk compared to alternatives. Aspirin for primary prevention of heart disease was moved to “avoid initiating” in older adults, aligning with broader guidelines that the bleeding risks outweigh the benefits for people who haven’t already had a cardiac event. Opioids were added to the list of medications that can worsen delirium, and anticholinergic drugs (found in many allergy, sleep, and bladder medications) were flagged for people with a history of falls or fractures.
Under-Prescribing Is a Problem Too
Medication problems in older adults aren’t limited to taking too much. About 35% of hospitalized older patients are missing at least one medication they should be taking. Some studies put that number closer to 58% among acutely ill seniors. Fear of polypharmacy, ageism in prescribing, or simply losing track of what’s needed across multiple providers can all lead to gaps. A patient might be on eight medications but still lack the statin or blood pressure drug that would prevent a stroke. The challenge is finding the balance between avoiding unnecessary drugs and ensuring necessary ones aren’t omitted.
Why People Miss Doses
Even when prescriptions are appropriate, non-adherence is widespread among older adults. The reasons are layered. Memory deficits top the list: forgetting a dose because of a change in routine or simple interruption is the most commonly reported barrier. Complex regimens with multiple drugs taken at different times of day and in different forms (pills, inhalers, patches) create opportunities for unintentional mistakes, particularly for people with any degree of cognitive decline.
Cost is another major factor, especially for those on fixed incomes managing several chronic conditions. Some people intentionally skip doses to stretch a prescription. Others stop medications because of side effects they haven’t discussed with a provider, a perceived lack of benefit, or social stigma around taking so many pills. Physical challenges like difficulty swallowing large tablets or trouble opening packaging also play a role that’s easy to overlook.
Medication Reconciliation Reduces Errors
One of the most effective strategies for preventing drug-related harm is medication reconciliation, a structured process where a pharmacist or clinician reviews every medication a patient is taking, especially during transitions like hospital discharge. A Cochrane review of 20 studies found that formal reconciliation cut the risk of medication discrepancies by 47% compared to standard care. In concrete terms, about 559 out of every 1,000 patients had at least one error under standard care, compared to 296 out of 1,000 when reconciliation was performed.
The annual cost of adverse drug events for every 1,000 older adults in outpatient settings approaches $65,000, with more than a third of that tied to preventable events. That figure captures only ambulatory care and doesn’t account for hospitalizations, which are far more expensive.
Practical Steps That Lower Risk
If you’re managing medications for yourself or an aging family member, a few habits make a meaningful difference. Keep a single, updated list of every medication, including over-the-counter drugs and supplements, and bring it to every medical appointment. Ask at least once a year whether each medication is still necessary. Pharmacists can often spot interactions that individual prescribers miss, particularly when prescriptions come from multiple doctors.
Pill organizers and blister packs reduce unintentional missed doses, especially for people taking medications at different times of day. Simplifying the regimen itself, consolidating to once-daily formulations when possible or reducing the total number of drugs, has a more durable effect than any reminder system. When a new symptom appears, consider whether it might be a side effect of an existing medication before assuming it’s a new problem that needs its own prescription.