On The Cover
Loren Bonner
American society has witnessed an increased use and social acceptance of cannabis for both purported therapeutic purposes and recreation. But let’s be honest: The safety profile of cannabis is undeniably incomplete.
The cannabis regulatory landscape across the United States for the past 30 years has been complex and complicated and remains uncertain at a federal level, giving health care providers like pharmacists a much-needed role as experts and counselors for patients taking cannabis medically or otherwise.
The health risks of cannabis, particularly in vulnerable groups, as well as efficacy and safety considerations, are relevant for pharmacists regardless of practice setting, said Mary Barna Bridgeman, PharmD, from the Ernest Mario School of Pharmacy at Rutgers University in New Jersey.
Safety evaluations for cannabis, according to Bridgeman, include drug–drug interactions, pharmacokinetic considerations, adverse effects, dosing, and route of administration.
In an article published in the May–June 2025 issue of JAPhA, Bridgeman noted that she and her colleagues wanted to reach the broadest pharmacist audience to encourage colleagues to be aware of these current issues—including how the potential rescheduling of cannabis could have an effect on pharmacy practice “necessitating pharmacist awareness of fundamentals of clinical use.”
According to Kari Franson, PharmD, PhD, the population as a whole is not educated about cannabis’ pharmacodynamic action and pharmacokinetic differences. On top of this, most patients are not accessing cannabis through a health care provider who can counsel them on these issues.
“A health care provider could certainly help them make a better decision based on pharmacodynamics and kinetics,” said Franson, who is with the USC Mann School of Pharmacy and Pharmaceutical Sciences.
State laws on cannabis dispensing are as diverse as the cannabis plants being grown today. In Arkansas, for instance, the law requires each dispensary to retain a consultant pharmacist to provide annual training to dispensary agents to identify substance abuse and to be available to patients for consultation by phone or videoconference.
“Some patients will inquire about potential drug interactions, and the pharmacist will assess their current medications and check for interactions,” said Bradley Martin, PharmD, PhD, from UAMS College of Pharmacy in Arkansas.
In one case, for example, a pharmacist consultant in Arkansas performed a thorough medication history for a patient with cancer taking a few medications. The pharmacist checked for interactions and suggested initial starting doses of cannabis.
However, the cases are few and far between for a pharmacist consultant to be sought out to answer questions related to medical cannabis. According to Martin, he suspects pharmacists are being underutilized from what he hears in the field.
Prenatal cannabis use
Perhaps due to the decreased perception of harm fueled by the legalization of cannabis, prenatal cannabis use has nearly doubled over the past decade. Many patients use it to relieve morning sickness or manage stress and anxiety. However, most are unaware that tetrahydrocannabinol (THC), the psychoactive component of cannabis, can cross the placenta as can cannabidiol (CBD), the nonpsychoactive component of cannabis.
Tori Metz, MD, frequently gets questions from her patients about using cannabis during pregnancy. She believes findings from a study she led with fellow researchers at the University of Utah Health published December 12, 2023, in JAMA can inform clinicians as they talk to patients about the risks of cannabis use.
Metz and her research team conducted a study of more than 9,000 patients who were pregnant from eight medical centers across the United States and found that for the individuals who had cannabis metabolite in urine samples, there was a higher risk of adverse pregnancy outcomes, especially low birth weight for the baby, compared to nonexposure.
“I think that these findings really just reiterate that we need to continue advising pregnant people to abstain from cannabis use during pregnancy,” said Metz, vice chair of research of obstetrics and gynecology at University of Utah Health, during a press conference.
“Higher frequency of use, and higher concentrations of use, were associated with more adverse outcomes,” said Metz. “I think we can even tell patients that stopping at any point is helpful.”
The greater risk seen at higher levels of exposure is concerning, too. Today, cannabis products have a higher amount of THC and are stronger than the products that were available when the study data were collected, which was over 10 years ago. The health impacts of these more concentrated products remain largely unknown.
Natalie DiPietro Mager, PharmD, PhD, said it will be important to talk to all patients about the risks of cannabis exposure on pregnancy outcomes, especially as cannabis use increases with more states legalizing it for both recreational and medicinal use.
“I think pharmacists can play a key role in education and counseling for patients who are pregnant or patients considering pregnancy. Per the American College of Obstetricians and Gynecologists, use of marijuana for nausea and vomiting or other medicinal purposes during pregnancy is not recommended,” said DiPietro Mager, who is a professor of pharmacy practice at Raabe College of Pharmacy at Ohio Northern University. “Rather, patients should be advised to use therapies with better pregnancy-specific safety and efficacy data.”
According to cannabis best practice advice for managing chronic noncancer pain from the American College of Physicians (ACP) published in Annals of Internal Medicine on April 4, 2025, “Clinicians should advise against starting or continuing to use cannabis or cannabinoids to manage chronic noncancer pain in patients who are pregnant or breastfeeding or actively trying to conceive.”
In a more recent systematic review and meta-analysis published on May 5, 2025, in JAMA Pediatrics, researchers found that cannabis use in pregnancy was associated with greater odds of preterm birth, small for gestational age, and low birth weight even after adjusting for co-use of tobacco products.
Authors pointed out that confidence in these findings increased from low in the prior review from 2024 published in Cannabis and Cannabinoid Research to moderate in the current meta-analysis.
In a comment about the more recent JAMA Pediatrics findings, Marie Claire O’Dwyer, MPH, associate editor with NEJM Journal Watch, wrote that: “I find it works well to include cannabis routinely in conversations about substances to avoid during pregnancy—alongside smoking, alcohol, and certain medications. Presenting this information in a matter-of-fact way helps normalize the discussion, allows for education about potential maternal and fetal risks, and opens the door for addressing misconceptions or offering cessation support when needed.”
Hidden dangers for certain groups
As a psychiatric pharmacist, Megan Maroney, PharmD, said on a daily basis she encounters how cannabis can be harmful to an individual’s mental health.
“With the increased potency of THC content in particular, we are seeing a lot of cannabis-induced psychosis,” said Maroney, who coauthored the JAPhA paper with Bridgeman.
“Patients with a history of mental illness, or a family history, may be particularly vulnerable to the adverse psychiatric effects of cannabis, and THC is a known risk factor for the development of schizophrenia, particularly in those with a genetic risk, with heavy or high potency use, and those who start at an earlier age.”
Cannabis use—particularly high use—increases the risk of developing cannabis use disorder; anxiety or depression; cannabis hyperemesis syndrome, which is unrelenting nausea and painful vomiting; and cannabis-induced psychosis and schizophrenia.
In another best practice guideline from ACP, the authors advise clinicians to “counsel the following subgroups of patients that the harms of cannabis or cannabinoid use for chronic noncancer pain are likely to outweigh the benefits: young adult and adolescent patients, patients with current or past substance use disorder, patients with serious mental illness, and frail patients and those at risk for falling.”
It should come as no surprise that cannabis is the most common illicit substance used during adolescence. But it can have a lasting impact on brain development.
Bridgeman acknowledged that with the increased social acceptance that cannabis is a benign substance, she sees many adolescents and even preadolescents engaging in regular cannabis use without much knowledge about the potential consequences on brain development, which can include learning difficulties and lower IQ.
“Patients at risk for depression and substance use disorders are also particularly vulnerable populations that may be adversely impacted by cannabis use,” said Maroney, who is a clinical associate professor from the Ernest Mario School of Pharmacy at Rutgers University.
Cannabis use among older adults is increasing, too. Franson said they are the fastest growing users today.
“The effects of cannabis superimposed on the pharmacokinetic changes associated with aging and with concomitant medication use and multimorbidity frequently seen in this population is a particular concern,” said Franson.
“The increased THC potency has definitely been linked with the increased risk for psychosis and also possibly depression and suicidality. It also definitely increases the risk of cannabis use disorder,” said Maroney.
If an individual is using a high potency THC product, which is more than 10% to 20% THC, on a regular basis, then their risk of developing cannabis use disorder dramatically increases, said Maroney. This is especially true if the individual starts using cannabis at a young age.
A hidden law
A federal law, 21 CFR § 1306.26–Dispensing without prescription, states that “A controlled substance listed in Schedules II, III, IV, or V which is not a prescription drug as determined under the Federal Food, Drug, and Cosmetic Act, may be dispensed by a pharmacist without a prescription to a purchaser at retail…” The law has existed since the 1970s and was originally intended for paregoric.
According to Kari Franson, PharmD, PhD, with the USC Mann School of Pharmacy and Pharmaceutical Sciences in California, this law could present an opportunity for cannabis within the context of pharmacy, for example pharmacists compounding medical cannabis, since cannabis is not yet an FDA-approved product.
“This to me is a possible route forward,” said Franson. “I think this is a way in which we can really help.” ■
More hidden dangers
According to ACP’s best practices, clinicians should advise patients against the use of inhaled cannabis to manage chronic noncancer pain.
Smoking any substance can have potential adverse pulmonary effects such as asthma or COPD exacerbations.
“With vaping, there is some thought that it may be less harmful to the lungs, but it is certainly not risk free,” said Maroney. “We’ve seen that with the reports of E-cigarette and Vaping-Associated Lung Injury (EVALI) in healthy young people, for example.”
According to Maroney, the pharmacokinetics and time course of the effects of THC depend on the route of administration.
THC is rapidly absorbed when it is inhaled—smoked or vaporized, said David Gorelick, MD, in an NEJM article from December 2023.
“It appears in plasma within seconds, with peak concentration occurring in 5 to 10 minutes,” wrote Gorelick. “In contrast, oral administration of THC results in slow absorption, with peak plasma concentration occurring in 2 to 6 hours.”
Today, vaping cannabis from an e-cigarette type of device is becoming much more popular than smoking it.
Maroney noted there is also the potential for inhaling adulterants or carcinogens with vaping, just like there is with tobacco products.
“Some patients may also be unintentionally exposed to tobacco when smoking what they assume is cannabis,” she said.
As a pharmacist, Maroney said she is always concerned about the possibility of CYP1A2-related drug interactions with smoking. “That is not just isolated to tobacco products. The act of combustion itself causes the production of polyaromatic hydrocarbons which can induce CYP1A2. This has important implications for several medications, including several antipsychotics, making the risk of developing psychosis in patients with psychotic disorders even greater,” said Maroney.
High potency
Bridgeman thinks that cannabis products are more potent today because of consumer demand, especially in the adult use or recreation market.
“[This] has likely driven innovation in cultivation and has resulted in more potent cannabis products in the marketplace over time,” said Bridgeman.
Higher THC concentrations in the plant also result in lower CBD production, Bridgeman said.
“CBD may offset some of the undesirable effects of THC from a therapeutic perspective,” said Bridgeman.
THC levels in cannabis research are also less potent than what individuals are actually consuming.
Research on cannabis dose and response are severely lacking, according to Franson. In general, the research on the health effects of cannabis is sparse because cannabis remains federally illegal.
“I do think were marijuana rescheduling to occur, there will be opportunities, for example, making it easier to conduct research related to clinical health effects and potentially expanded pathways to access funding and support for research efforts,” said Bridgeman. “Additionally, rescheduling might help to expand and incentivize development of federally approved cannabis derived– or cannabinoid medications, since at present, we lack comprehensive, controlled clinical trials to elucidate efficacy and harms.”
“We’d all love to be able to recommend a product, but we can’t because nothing is reviewed consistently,” said Franson. The rule is always to start low and go slow when there’s no reliable dose or product. ■
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