Stanford doctors flag five risks that make cannabis dangerous after 65

Specialists at Stanford Medicine have laid out five specific reasons cannabis becomes riskier for people over 65, a caution aimed at a group whose use of the drug has grown sharply as legalization has spread. The concerns center on the heart, on falls, on memory and thinking, on interactions with prescription drugs, and on the potential for dependence — a combination that makes an aging body more vulnerable to marijuana’s effects than a younger one.

The warning is not a claim that cannabis is uniquely dangerous, but a reminder that the same dose can land very differently in an older person. As more seniors turn to cannabis for sleep, pain or anxiety, physicians who treat them have started to spell out where the physiology of aging and the pharmacology of the drug collide.

The five risks Stanford specialists highlight

The guidance groups the dangers into five categories. According to the Stanford experts, modern cannabis can raise the chances of heart problems, falls, memory issues, dangerous drug interactions and even addiction, particularly in people over 65. Each of those is a recognized hazard on its own; what the specialists emphasize is that older adults are more exposed to all of them at once, and that the effects can compound.

The falls risk draws particular attention because of how directly it can lead to serious injury. Cannabis can cause dizziness or a drop in blood pressure upon standing — a condition called orthostatic hypotension — and both make a stumble more likely. In an older person, a single fall can fracture a hip or cause a head injury, turning a transient side effect into a life-altering event.

Why an aging body handles the drug differently

A central reason the same amount of cannabis hits harder later in life is metabolism. Older adults break the drug down more slowly, so it lingers in the body and its effects can last longer than expected. That slower clearance means a dose that felt manageable years earlier can produce stronger or more prolonged impairment, raising the odds of confusion, sedation and unsteadiness.

Today’s cannabis products also tend to be far more potent than the marijuana many older users may remember, which widens the gap between an anticipated effect and the actual one. The Stanford specialists frame this as a matching problem: a more concentrated drug, processed by a body that eliminates it less efficiently, in a person whose balance and cognition may already be more fragile. The result is a higher chance that the drug tips an older adult into a genuinely risky state.

The interaction problem with prescription drugs

For a population that often takes several daily medications, drug interactions may be the least visible but most consequential risk. Cannabis compounds can interfere with the same liver enzymes the body uses to process many prescriptions, altering how much of a given drug ends up circulating. In Stanford’s account, CBD — the non-intoxicating component of cannabis — can interfere with the enzymes that break down medications such as blood thinners, potentially raising drug levels and increasing the danger of bleeding after an injury or fall.

That specific pathway ties several of the warnings together: a fall made more likely by dizziness becomes more dangerous still if a blood thinner is circulating at a higher-than-intended level. Because older adults are the age group most likely to be on anticoagulants, blood-pressure drugs and sedatives, they are also the group where an unexpected interaction is most likely to matter. The specialists urge that cannabis use be treated as part of a full medication picture rather than something separate from it.

What the guidance means for older users

The Stanford message is one of caution rather than prohibition. The specialists are not arguing that every older adult must avoid cannabis, but that the decision deserves the same care given to starting any drug with real side effects — ideally in conversation with a clinician who knows the person’s other medications and health conditions. Disclosing cannabis use to a doctor is presented as especially important, since it is often left off the list of substances a patient reports.

Practical implications follow from the biology. Slower metabolism argues for lower doses and longer waits before repeating them; the falls risk argues for avoiding use in situations where a stumble would be dangerous; and the interaction risk argues for reviewing cannabis alongside prescriptions rather than treating it as harmless by default. The addiction concern, though sometimes underappreciated in older users, is a reminder that dependence can develop at any age.

Taken together, the five risks describe a drug whose margin for error narrows with age. Cannabis remains legal and widely used, and many older adults will continue to reach for it, but the Stanford framework gives them and their physicians a concrete checklist — heart, falls, cognition, interactions and dependence — for weighing whether, and how carefully, to use it after 65.

This article was researched and written with the assistance of AI and reviewed by an editor prior to publication.

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