S2 | E13 Dr. Peter Grinspoon

Dr. Peter Grinspoon is one of the most credentialed guests I've had on this show — Harvard Medical School instructor, primary care doctor, addiction specialist at Massachusetts General Hospital — and yet he's remarkably candid about his own reckoning with addiction. Twenty years ago, he lost his medical license for three years after becoming addicted to prescription painkillers, driven by the unrelenting pressure of medical training and practice. Five years into his own recovery, the same board that monitored him hired him to help other physicians walk the same road, and that experience eventually led him into addiction medicine and cannabis clinical work full time.

Peter's relationship to cannabis is also deeply personal. He tells me about his older brother Danny, who used medical cannabis to manage chemotherapy-induced nausea in the early 1970s — right as Nixon's drug war was ramping up — and how it let Danny eat, keep weight on, and come downstairs to play with his little brother before he passed away from leukemia. That memory sits alongside his father's legacy: psychiatrist Lester Grinspoon, whose 1971 book Marijuana Reconsidered argued that criminalizing cannabis caused far more harm than the drug itself — an argument borne out by the roughly 20 million arrests for simple possession since, disproportionately affecting Black and brown communities.

We get into the real clinical picture: cannabis's proven uses for chronic pain, insomnia, anxiety, MS-related spasticity, and chemotherapy side effects, especially for seniors navigating the toxicity of alternatives like opioids and NSAIDs. But Peter doesn't sugarcoat the risks either — teens, pregnant or breastfeeding women, and anyone with a personal or family history of psychosis should steer clear, and heavy daily use can trigger a brutal condition called cannabinoid hyperemesis syndrome. He's candid about addiction too: cannabis absolutely can be addictive, just rarely fatal, which changes the calculus on how urgently it needs treating.

The conversation ranges from Carl Sagan's secretly-authored essay on cannabis and creativity (published pseudonymously as "Mr. X" in his father's book) to the dangers of hyper-concentrated botanical products like 7-OH kratom, to his frustration watching big cannabis conglomerates start to resemble Big Tobacco. Peter's writing a novel now, after three nonfiction books — including his memoir Free Refills and his most recent, Aging Well With Cannabis — and throughout, he keeps returning to the same core belief: harm reduction, nuance, and treating people with compassion rather than judgment.