There is no safe amount of cannabis.
En las salas de Stanford Medicine, los investigadores observan cómo una generación que envejeció desconfiando del cannabis ahora lo adopta en silencio para aliviar el dolor, el insomnio y la ansiedad. Lo que ha cambiado no es solo la actitud social, sino la sustancia misma: el cannabis de hoy es exponencialmente más potente que el de décadas pasadas, y los cuerpos que lo consumen son más vulnerables que nunca. Los médicos no piden abstinencia moral, sino precaución informada: el diálogo honesto entre paciente y médico es, en este momento, la única brújula confiable.
- El consumo de cannabis entre mayores de 65 años casi se duplicó entre 2021 y 2023, pero el conocimiento sobre sus riesgos reales no ha seguido el mismo ritmo.
- Los productos actuales contienen hasta 90% de THC en concentrados, una potencia que convierte una dosis 'moderada' en una experiencia impredecible y potencialmente peligrosa para un cuerpo envejecido.
- Los riesgos cardiovasculares son concretos y documentados: el uso regular de cannabis se asocia al 29% de los infartos y a un 20% más de riesgo de accidente cerebrovascular, sin que exista una dosis considerada segura.
- Muchos adultos mayores no informan a sus médicos sobre su consumo, creando puntos ciegos clínicos que pueden derivar en interacciones medicamentosas graves o sobredosis accidentales.
- Algunos especialistas reconocen beneficios terapéuticos posibles a dosis muy bajas y con supervisión profesional, pero advierten que sin ese acompañamiento, el riesgo supera con frecuencia al beneficio.
En Stanford Medicine, los investigadores observan una tendencia silenciosa pero significativa: cada vez más adultos mayores de 65 años recurren al cannabis para tratar el dolor crónico, los problemas de sueño y la ansiedad. Entre 2021 y 2023, el porcentaje de estadounidenses mayores que declararon usarlo casi se duplicó, pasando de menos del 5% al 7%. Sin embargo, los médicos que estudian este fenómeno advierten que los riesgos están siendo gravemente subestimados.
La psiquiatra Smita Das, profesora de Stanford Medicine, señala que no existe consenso médico sobre si el cannabis realmente funciona para las condiciones que los adultos mayores buscan tratar. Lo que sí está documentado son sus riesgos: enfermedades cardíacas, ciertos cánceres, adicción, deterioro cognitivo e interacciones impredecibles con medicamentos que muchos seniors ya toman. A esto se suma el problema de la potencia: mientras en los años 70 el cannabis contenía entre 1 y 4% de THC, hoy las flores legales promedian un 20%, algunos concentrados alcanzan el 90%, y el cannabis sintético ha sido vinculado a problemas cardíacos tan graves que varios estados lo han prohibido.
El cardiólogo Joseph Wu, director del Instituto Cardiovascular de Stanford, es categórico: no existe una cantidad segura de cannabis. Su investigación vincula el consumo regular con el 29% de los infartos en el país y un 20% de aumento en el riesgo de accidente cerebrovascular. Para alguien en sus setenta u ochenta años, esta advertencia no es abstracta.
Otro factor que preocupa a los especialistas es el silencio. Das ha observado que los adultos mayores frecuentemente no mencionan su consumo a sus médicos, a menos que se les pregunte directamente. Esto impide que los profesionales de salud detecten interacciones con tratamientos para la depresión, el alcohol u otras condiciones.
La enfermera especialista en geriatría Eloise Theisen ha visto resultados positivos en pacientes que usan dosis muy bajas bajo supervisión. Reconoce que el THC puede ser terapéutico en pequeñas cantidades, especialmente para quienes buscan alivio y bienestar en etapas avanzadas de la vida. Pero su mensaje es claro: esto requiere orientación profesional. Antes de que cualquier adulto mayor use cannabis, debe consultarlo con su médico. Las sobredosis accidentales ocurren, y la conversación honesta entre paciente y profesional de salud es donde comienza la seguridad.
At Stanford Medicine, researchers are watching a quiet shift in how older Americans are treating their ailments. More seniors over 65 are turning to cannabis—whether medical or recreational—to manage chronic pain, sleep problems, and anxiety. The trend is real: between 2021 and 2023, the share of Americans over 65 who reported using cannabis nearly doubled, climbing from under 5 percent to 7 percent. But the doctors sounding the alarm say the risks are being dangerously overlooked.
Smita Das, a psychiatrist and clinical associate professor at Stanford Medicine, points out that there is no broad medical consensus yet on whether cannabis actually works for the conditions older people are using it to treat. More troubling, she says, is what happens when aging bodies encounter the drug. The risks include heart disease, certain cancers, addiction, cognitive decline, and unpredictable interactions with the medications seniors are already taking. These are not theoretical concerns—they are documented in the scientific literature, and they matter more in people whose bodies are already fragile.
The potency problem is the first thing experts want older adults to understand. In the 1970s, cannabis flower contained between 1 and 4 percent THC, the compound responsible for its psychoactive effects. Today, legal cannabis flower averages around 20 percent THC. Some strains reach 35 percent. Concentrated products—oils, edibles, extracts—can contain nearly 90 percent THC. Synthetic marijuana, which some seniors might encounter, has been linked to heart problems severe enough that several states have made it illegal. A 65-year-old taking what they think is a modest dose may be consuming something far more potent than they realize.
The cardiovascular risks are particularly acute. Joseph Wu, who directs Stanford's Cardiovascular Institute, has studied how cannabis inflames blood vessel walls in animal models. His research connects regular cannabis use to 29 percent of heart attacks in the country and a 20 percent increase in stroke risk. "There is no safe amount of cannabis," Wu states plainly. "Even low doses and occasional use are associated with vascular inflammation. Abstinence is the safest choice for heart health." For someone in their seventies or eighties, this is not an abstract warning.
Addiction is another reality that catches people off guard. Das notes that about 30 percent of cannabis users develop a disorder related to it. Older adults, she has observed, often do not mention their cannabis use to their doctors unless directly asked. "I've noticed that seniors don't always disclose it," she says. "It's not a population we traditionally associate with cannabis use." This silence matters because a doctor treating depression or alcohol use disorder might never know their patient is also using cannabis, missing a crucial piece of the clinical picture.
The evidence for cannabis as medicine is mixed and limited. The FDA has not approved cannabis itself, though it has approved certain cannabis-derived compounds like cannabidiol and dronabinol. Studies show some pain relief, but placebo effects are substantial, and results are inconsistent. Eloise Theisen, a geriatric nurse specialist in cannabis therapy at Stanford, has seen positive outcomes in her own patients, particularly at very low doses. She argues that THC, despite its reputation, can be therapeutic in small amounts, and for elderly patients with limited time remaining, the ability to experience joy and relief matters. But she is adamant: this requires professional oversight.
Theisen's final point is the most practical. Before any senior uses cannabis, they should consult their primary care doctor. Accidental overdoses happen. Patients end up in emergency rooms confused about what went wrong, or they abandon the treatment because they misunderstood the dose or the timeline. A healthcare provider can help navigate the actual risks, check for drug interactions, and monitor for harm. The conversation between doctor and patient—honest and specific—is where safety begins.
Notable Quotes
There is no safe amount of cannabis. Even low doses and occasional use are associated with vascular inflammation. Abstinence is the safest choice for heart health.— Joseph Wu, director of Stanford's Cardiovascular Institute
I've noticed that seniors don't always reveal their cannabis use to their doctors unless asked specifically. It's not a population we traditionally associate with cannabis use.— Dr. Smita Das, psychiatrist at Stanford Medicine
The Hearth Conversation Another angle on the story
Why are more seniors using cannabis now than five years ago?
It's partly because cannabis is more available and legal in more places, but also because older people are genuinely suffering from pain, insomnia, and anxiety. They hear that cannabis might help, and they try it. The problem is they're often not talking to their doctors about it.
What's the biggest surprise in the Stanford research?
That there's no safe dose. People assume a little bit won't hurt. But the research shows even occasional, low-dose use is linked to inflammation in blood vessels. For someone with a heart already under stress, that matters.
If cannabis is so risky, why do some doctors like Theisen support it?
Because she's seeing real relief in patients who have months or years left to live. For them, the ability to sleep, to feel less pain, to experience joy—that has value. But it has to be done carefully, with tiny doses, and with a doctor watching.
What would happen if a senior took cannabis without telling their doctor?
They might end up in the emergency room from an accidental overdose. Or they might be taking it alongside medications that interact badly with it. Or they might develop an addiction without realizing it. The silence is the danger.
Is cannabis more potent now than it used to be?
Dramatically. What was 2 percent THC in the 1970s is now 20 to 35 percent in flower, and up to 90 percent in concentrates. A senior thinking they're having a modest experience might be overwhelmed.
So what should a senior do if they're considering cannabis?
Ask their doctor first. Not their neighbor, not the dispensary clerk. Their doctor. That conversation is where the real safety happens.