Stanford Warns: 5 Cannabis Risks Every Adult Over 65 Must Know

Seniors are the fastest-growing group of cannabis consumers in America. A 2025 study out of the University of Colorado found that cannabis use among adults over 60 surged 46 percent in just two years, climbing from 4.8 percent in 2021 to 7 percent in 2023. The reasons are intuitive — chronic pain, insomnia, anxiety — and the cultural stigma that once kept older generations away from the plant has all but evaporated in the age of legal dispensaries and Medicare CBD pilots.

But a new advisory published by Stanford University experts on May 15, 2026, is urging caution. The researchers identified five specific risks that make cannabis use meaningfully more dangerous for people over 65 than for younger adults. The findings do not argue against medical use under supervision; rather, they highlight the ways in which aging physiology interacts with cannabinoids differently than most consumers expect.

Here is what the Stanford team found — and what every older adult, caregiver, and physician needs to understand.

Risk 1: Dangerous Drug Interactions with Common Medications

The single biggest concern Stanford researchers flagged is pharmacokinetic drug interactions. Adults over 65 take an average of five or more prescription medications daily. Both THC and CBD are metabolized by the cytochrome P450 enzyme system in the liver — the same system that processes blood thinners like warfarin, statins like atorvastatin, blood pressure medications, benzodiazepines, and dozens of other commonly prescribed drugs.

When cannabis compounds compete for the same liver enzymes, they can either amplify or diminish the effects of prescription medications. CBD, in particular, is a potent inhibitor of CYP3A4 and CYP2D6 enzymes, meaning it can cause certain drugs to accumulate in the bloodstream to dangerous levels. The result can be anything from excessive sedation to bleeding events in patients on anticoagulants.

This is not a theoretical concern. Case reports in clinical literature have documented patients on warfarin experiencing dangerous INR spikes after adding CBD products to their routines without informing their physicians.

Risk 2: Increased Fall Risk and Bone Fractures

Falls are already the leading cause of injury-related death among adults over 65 in the United States, accounting for more than 38,000 deaths annually. Cannabis can exacerbate this risk through multiple mechanisms.

THC causes dizziness, impaired balance, and orthostatic hypotension — a sudden drop in blood pressure when standing up. For a 30-year-old, a momentary wobble might be inconsequential. For a 75-year-old with osteoporosis, it can mean a hip fracture that leads to hospitalization, surgery, and a cascade of complications.

The Stanford team emphasized that edibles present a particular hazard because their delayed onset — often 60 to 120 minutes — can catch users off guard. An older adult who feels nothing after an hour may take a second dose, only to experience compounded effects while navigating stairs or getting up at night.

Risk 3: Cardiovascular Stress

Cannabis raises heart rate and can cause temporary fluctuations in blood pressure. For younger adults with healthy cardiovascular systems, these effects are generally benign. But for seniors already managing hypertension, atrial fibrillation, or a history of cardiac events, the additional cardiovascular stress is not trivial.

Research published earlier in 2026 through the MARY-JANE trial is actively investigating the relationship between THC and cardiac arrhythmias. While results are still pending, the Stanford advisory warns that older adults with known heart conditions should treat cannabis as they would any other cardiovascular stimulant — with appropriate medical oversight and caution.

The risk is compounded by the tendency of older adults to use higher-potency products. In the 1970s, cannabis typically contained between 1 and 4 percent THC. Today, legal flower averages around 20 percent, and concentrates can exceed 90 percent. Many seniors who last used cannabis decades ago are unprepared for this potency shift.

Risk 4: Cognitive Effects and Memory Impairment

While a 2026 University of Colorado study found associations between cannabis use and larger brain volumes in middle-aged and older adults, the Stanford team paints a more nuanced picture. Age-related changes in cannabinoid receptor density and brain plasticity mean that the cognitive effects of THC — including short-term memory disruption, slowed processing speed, and impaired executive function — can be more pronounced and longer-lasting in older adults.

A separate March 2026 study found that THC can create false memories, a concern that takes on additional significance for seniors who may already be experiencing age-related cognitive decline. The overlap between cannabis-induced cognitive effects and early dementia symptoms can also complicate clinical assessments, potentially delaying diagnosis of serious conditions.

The researchers stressed that these effects are dose-dependent and most pronounced with high-THC products. Low-dose CBD-dominant formulations carry substantially less cognitive risk.

Risk 5: Respiratory Complications from Smoking

For older adults who smoke cannabis flower — still the most common consumption method among new senior users — the respiratory risks compound with age. Reduced lung capacity, weakened immune response, and increased susceptibility to respiratory infections all mean that inhaled cannabis smoke carries greater risk for seniors than for younger users.

Chronic bronchitis symptoms, including persistent cough and increased mucus production, are well-documented in regular cannabis smokers of all ages. But for seniors already managing conditions like COPD or asthma, adding inhaled irritants can accelerate decline.

The Stanford team recommends that older adults who choose to use cannabis consider non-inhaled alternatives such as tinctures, low-dose edibles, or topical applications, which bypass the respiratory system entirely.

What Seniors Should Do

The Stanford advisory is not a call to abandon cannabis. It is a call for informed decision-making. The researchers outlined several practical steps for older adults considering cannabis use.

First, always consult with a physician or pharmacist before adding any cannabis product to an existing medication regimen. Bring a list of current prescriptions and discuss potential interactions explicitly.

Second, start with the lowest effective dose and choose products with clearly labeled cannabinoid content. Products with balanced THC-to-CBD ratios or CBD-dominant formulations tend to carry lower risk profiles.

Third, avoid smoking as a delivery method. Tinctures, capsules, and topicals offer more predictable dosing and eliminate respiratory risk entirely.

Fourth, be honest with healthcare providers about cannabis use. A 2026 survey found that many seniors skip telling their doctors about cannabis consumption due to lingering stigma — a silence that can have real clinical consequences.

Finally, keep cannabis products secured and clearly labeled. Edibles that look like ordinary food items have been responsible for accidental overconsumption events in households with older adults.

The Bigger Picture

The rapid growth in senior cannabis adoption is not going to slow down. Medicare's new CBD pilot program, expanded medical cannabis access in states like Georgia and Iowa, and the broader cultural normalization of the plant all point toward continued uptick among older demographics.

That makes evidence-based risk communication more important than ever. Stanford's advisory fills a critical gap in a conversation that has often defaulted to either blanket prohibition or uncritical enthusiasm. Cannabis can be a useful therapeutic tool for older adults — but only when used with the same level of informed caution applied to any other medication.

The era of "it's just a plant" has given way to the era of personalized medicine. For adults over 65, that distinction could not matter more.

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