Dr. Peter Grinspoon’s 18 Principles for Safer Cannabis Use

Seeing Through the Smoke by Peter Grinspoon

Cannabis has gone mainstream. One in seven Americans uses some sort of CBD product. Ninety-four percent of Americans support legalization of medical marijuana, and 69 percent now believe in comprehensive legalization for adult use. In many places, consumers can now openly buy everything from their favorite strain of Sativa to CBD pillowcases to THC bath bombs. Still, that doesn’t mean that myths and misconceptions don’t persist. Whether it’s the hard-dying, fear-mongering lies spun by the War on Drugs and other prohibition campaigns or the utopian daydreams of long-time stoners and cannabis enthusiasts, we remain confused and misinformed about the leaf that we have been using for at least five-thousand years. Enter Peter Grinspoon, a physician, cannabis expert, and son of the late Dr. Lester Grinspoon, a psychiatrist and academic who risked a Harvard career to challenge laws and beliefs about marijuana long before it was fashionable.

In his new book, SEEING THROUGH THE SMOKE: A CANNABIS SPECIALIST UNTANGLES THE TRUTH ABOUT MARIJUANA (Prometheus Books, April 20, 2023), Grinspoon offers 18 concise principles for safer cannabis use. See a few of them below.


1. Keep dosages of THC as low as possible. As with most other drugs and medicines, the lower the (effective) dose, the less harmful. We fetishize high THC in the United States at the expense of other medicinal components of the cannabis plant. Periodic tolerance breaks help keep the dosage that is needed low.

2. Don’t smoke! (Unless you are a very occasional user). There’s no reason to expose yourself to combustion products, such as tar, benzene, polycyclic aromatic hydrocarbons, etc. (Even though cannabis has never been shown to cause lung cancer or COPD, there’s no reason to inhale all of this junk.) If you prefer, or need, to use cannabis inhalationally, use a dry herb vaporizer, which doesn’t combust the cannabis but heats it to a lower temperature and produces a less irritating vapor. Or explore edibles, tinctures, inhalers, oils, suppositories, patches, and lotions—there are lots of options these days.

3. Use with caution or avoid usage if you have a history of addiction or any history or family history of mental illness, particularly psychosis or schizophrenia. Speak with your doctor (or, with a doctor that is able to be helpful, if your doctor isn’t up to date on cannabis) and exercise extreme caution before starting cannabis. The use of cannabis, or any drug, can also make certain mental illnesses more difficult to diagnose and treat.

4. Use with great caution as well if you have a history of coronary disease or an arrhythmia. Involve your medical providers and keep the dosages very low.

5. Do not use during during pregnancy or while breastfeeding, if feasible, until we understand this area much better, as it has not been shown to be safe. If you are using, please let your care teams know. Care teams, on their end, must respond with compassion, not stigma and punitiveness.

6. If you have a particularly good or bad reaction to a particular strain or ‘chemovar’, write it down. Journaling is good practice in any case—dosage, benefits, side effects, formulations, and delivery mechanisms.

7. Ask your doctor, or a cannabis specialist, about any potential reactions there may be between THC, CBD, and any medications you are taking. This is particularly true if you are on blood thinners or other medications that need to be kept within a narrow range (e.g., antiepileptics, immunosuppressants, chemotherapeutic agents). Also, if you use cannabis frequently, make sure the anesthesiologist knows, before surgery, as you might have higher anesthesia requirements.

8. Know the relevant laws in your area, and don’t get tangled up with law enforcement. You can’t (yet) legally fly with cannabis. Other states where the legality is different (or absent) might not accept your medical cannabis card and could even arrest you if they don’t have legal medical cannabis.

VIDEO: www.youtube.com/@drpetergrinspoon


Peter Grinspoon, M.D. is a primary care physician and cannabis specialist at Massachusetts General Hospital and has been an Instructor in Medicine at Harvard Medical School for the last twenty-five years. He is a certified Health and Wellness Coach as well as a board member of the advocacy group Doctors for Cannabis Regulation. He has been providing medical cannabis care for patients for two decades. He served as the Associate Director of the Massachusetts Physician Health Service, helping hundreds of other physicians with their addictions.

Dr. Grinspoon is a widely recognized expert on the therapeutic uses, the science and the social history of cannabis, as well as on addiction, psychedelics and drug policy. He regularly appears as an expert on national television and radio programs, including The Daily Show, Good Morning America, NPR’s All Things Considered, NBC Nightly News, C-SPAN’s Washington Journal, Fox and Friends and Fox News. He is quoted frequently in the national media, in such venues as People, the New York Times, New York Magazine, the Washington Post, USA Today, the Wall Street Journal, the Chicago Tribune, and the Boston Globe. He is a TEDX speaker.

Grinspoon’s Harvard Health articles have reached tens of millions of readers, have been widely referenced in the national media, and have been cited in congressional testimony. His writing has been published in The Nation, the Los Angeles Times Narrative Inquiry in Bioethics, MedPage Today and in Salon.

He is the author of the groundbreaking memoir Free Refills: A Doctor Confronts His Addiction, was the expert witness in the successful citizens’ 2019 lawsuit against the Massachusetts “Vape Ban” and a special consultant on addiction issues to Jagged Little Pill’’s pre-Broadway run at the American Repertory Theater.


“Seeing through the Smoke is packed with accessible, engaging, and useful information delivered with the heart of a humanitarian and the commonsense of a sensible scientist. Dr. Grinspoon has done us a huge public service. Read his book!”

—Carl Hart, Columbia University Professor and author of Drug Use for Grown-ups

“As marijuana goes mainstream, many lingering doubts, contradictions, lies, and half-truths remain entrenched in the public debate. Peter Grinspoon has written a delightfully readable, informative, and timely book that shines a clear light through this maze of misunderstandings. Following in the family tradition – Grinspoon’s father Lester wrote two seminal books on marijuana – Seeing Through the Smoke can help heal the scars left by the government’s failed war on cannabis.”

—Rick Doblin, PhD, founder and executive director of the Multidisciplinary Association for Psychedelic Studies (MAPS)

“Peter Grinspoon is an ex-addict, marijuana enthusiast, and cannabis prescribing physician with a professional and moral obligation to know and tell the truth about cannabis’ relationship to driving, pregnancy, psychosis, autism, addiction, sleep, cancer, and much more. Never before have I read such an engaging and accessible review of the evidence.”

—Ethan Nadelmann, founder and former executive director of the Drug Policy Alliance

“An unflinching and utterly personal journey through the often-confusing cannabis landscape. Readers will delight in the historical as well as the scientific focus brought to life by Grinspoon, whose roots and professional experience provide a unique and fascinating perspective. Seeing through the Smoke has something for everyone – from the novice to the expert and everyone in between with an interest in cannabis.”

—Staci Gruber, MD, Director of Marijuana Investigations for Neuroscientific Discovery (MIND) and professor of psychiatry at Harvard Medical School

“When I was a child, I saw my great uncle, a physician, helping my cousin to clean and prepare his medicine – pot– so he could tolerate his chemotherapy treatments. Seeing through the Smoke clearly lays out the case for cannabis as a medicine while thoughtfully and calmly outlining its risks. Not only should everyone read this book, but they should share it with their loved ones, too.”

—Julie Holland, MD, author of Good Chemistry: The Science of Connection, From Soul to Psychedelics

“Peter Grinspoon is uniquely qualified to dispense verifiable knowledge about cannabis use and misuse as both prescriber of therapeutic cannabis to qualified medical patients and a councilor to cannabis misusers. Steeped in a deep pharmacological understanding of cannabis and aided by up-to-date analysis of scientific cannabis-related studies, Seeing through the Smoke amplifies a voice trusted by both sides of the ongoing debate about functional and responsible cannabis policies post-prohibition.”

—Allen St. Pierre, former Executive Director of NORML

“Seeing Through the Smoke provides refreshing insights into the biases that have challenged cannabis research to date. Grinspoon presents both sides of the divisive issues polarizing society today, allowing the reader to reconsider what is and isn’t true about cannabis. Honest, personal, poignant, comprehensive, and totally current, this book emphatically reminds us that the absence of evidence is not the same as evidence of absence of effectiveness for this extremely therapeutic botanical.”

—Donald I. Abrams, professor emeritus of medicine, University of California San Francisco