When Cannabis Was Medicine: America's Forgotten Pre-Prohibition Pharmacopeia

If you've ever wondered why cannabis was made illegal in the first place, it helps to understand what it was before—and the answer might surprise you. For nearly a century before prohibition, cannabis was one of the most commonly prescribed medicines in America. It sat on pharmacy shelves alongside morphine, quinine, and aspirin. Doctors recommended it for everything from migraines to menstrual cramps. And its removal from the medical establishment had far more to do with politics, racism, and bureaucratic turf wars than with any scientific finding about its safety or efficacy.

A Medicine Arrives in America

The story of cannabis in Western medicine typically begins with William Brooke O'Shaughnessy, an Irish physician working for the British East India Company in Calcutta during the 1830s. O'Shaughnessy observed Indian practitioners using cannabis preparations for a variety of ailments and began his own experiments—first on animals, then on patients suffering from muscle spasms, tetanus, rabies, and cholera. His findings, published in 1839, introduced the therapeutic potential of cannabis to the English-speaking medical world and sparked immediate interest on both sides of the Atlantic.

By the 1850s, cannabis had made its way into the United States Pharmacopeia (USP), the official compendium of drugs recognized by the American medical establishment. Its first listing appeared in the 1850 edition, making cannabis as officially legitimate as any other drug available to physicians. The USP described cannabis preparations as useful for treating neuralgia, tetanus, typhus, cholera, rabies, dysentery, alcoholism, opiate addiction, anthrax, leprosy, incontinence, gout, convulsive disorders, tonsillitis, insanity, excessive menstrual bleeding, and uterine hemorrhage—a list that reflects both the genuine versatility of cannabinoid medicine and the 19th century's tendency toward therapeutic optimism.

The Golden Age of Cannabis Medicine

Between the 1850s and the early 1900s, cannabis was one of the most widely available medicines in the United States. Pharmaceutical companies including Eli Lilly, Parke-Davis (now Pfizer), and Squibb marketed cannabis extracts, tinctures, and preparations to physicians and directly to consumers. These products were available at pharmacies without prescription—just like aspirin or cough syrup today.

The applications were broad. Physicians prescribed cannabis tinctures for pain relief, particularly for conditions where opiates were considered too strong or too habit-forming. It was used as a sleep aid, an appetite stimulant, an anticonvulsant, and a treatment for migraines. Women's health practitioners recommended cannabis for menstrual cramps and other gynecological complaints—a use that modern research on cannabinoids and the endocannabinoid system's role in reproductive health is beginning to validate.

Cannabis also appeared in numerous patent medicines—the over-the-counter preparations that filled drugstore shelves in the era before FDA regulation. These products, sold under names like "Piso's Cure" and "One Day Cough Cure," often combined cannabis with other active ingredients and were marketed for everything from baby teething pain to depression. The quality and dosing of these preparations varied wildly, a problem that would eventually contribute to the push for pharmaceutical regulation.

The Medical Establishment's Relationship with Cannabis

It's important to note that cannabis occupied a respected but not uncomplicated position in 19th-century American medicine. Physicians recognized both its therapeutic value and its limitations. The main challenge was dosing consistency—cannabis preparations varied significantly in potency depending on the source plant, growing conditions, extraction method, and storage duration. Unlike morphine, which had been isolated as a pure compound in 1804, cannabis remained a whole-plant preparation with unpredictable strength.

This inconsistency frustrated physicians who valued precision. As the medical profession moved toward standardized pharmaceuticals in the late 1800s and early 1900s—driven partly by the germ theory of disease and the rise of evidence-based medicine—cannabis began to fall out of favor with some practitioners. The development of aspirin in 1899, barbiturates in the early 1900s, and eventually injectable opioids provided alternatives that were easier to dose precisely, even if they came with their own significant risks.

However, cannabis never fell completely out of medical use based on these clinical considerations alone. As late as the 1930s, pharmaceutical companies were still actively marketing cannabis preparations, and many physicians continued to find them useful for specific applications.

The Politics of Prohibition

What actually ended cannabis medicine in America was not a medical decision but a political one. The Marihuana Tax Act of 1937, championed by Federal Bureau of Narcotics Commissioner Harry Anslinger, imposed a prohibitive tax on cannabis that effectively criminalized its production, distribution, and use—including medical applications.

The American Medical Association actually opposed the Marihuana Tax Act. Dr. William C. Woodward, the AMA's legislative counsel, testified before Congress that the organization knew of no evidence that cannabis was a dangerous drug and objected to the restrictive legislation. His testimony was largely ignored. The political momentum behind prohibition—fueled by sensationalized media coverage, racial fearmongering about Mexican immigrants and Black jazz musicians, and Anslinger's bureaucratic ambitions—proved more powerful than medical expertise.

The consequences were swift. In 1942, cannabis was removed from the United States Pharmacopeia, ending its nearly century-long recognition as an official medicine. Medical research on cannabis became extraordinarily difficult as the regulatory framework treated it as a dangerous narcotic with no accepted medical use—a classification that persists at the federal level today as Schedule I under the Controlled Substances Act of 1970.

The Erasure of Medical History

One of the most remarkable aspects of cannabis prohibition is how thoroughly it erased the public memory of cannabis as medicine. Within a generation of the Marihuana Tax Act, most Americans had no idea that cannabis had ever been a mainstream pharmaceutical product. Medical schools stopped teaching about cannabinoid therapeutics. Pharmacy histories glossed over or omitted cannabis entirely. The plant's association shifted completely from medicine cabinet to criminal court.

This erasure was so effective that when California passed Proposition 215 in 1996—the first modern medical cannabis law—opponents could plausibly argue that the idea of cannabis as medicine was a smokescreen for recreational legalization. The notion that cannabis had been a recognized American medicine for nearly a century had been lost to public consciousness.

Echoes in Modern Medicine

The irony of this history becomes sharper every year. Many of the conditions that 19th-century physicians treated with cannabis—chronic pain, muscle spasms, insomnia, seizure disorders, menstrual cramps—are the same conditions that modern medical cannabis patients report finding relief from. The discovery of the endocannabinoid system in the 1990s provided a biological explanation for why cannabis medicines worked: the human body has a built-in signaling system that cannabinoids interact with, regulating pain, mood, appetite, sleep, and immune function.

Modern pharmaceutical science has also confirmed several specific applications that pre-prohibition doctors used cannabis for. Epidiolex, an FDA-approved CBD medication, treats the same seizure disorders that 19th-century physicians used cannabis tinctures to manage. Dronabinol and nabilone, synthetic THC preparations, are approved for nausea and appetite stimulation—applications that their historical predecessors addressed with whole-plant preparations.

The difference, of course, is that today's pharmaceutical cannabinoids undergo rigorous clinical testing and deliver precise, consistent dosing—addressing the very inconsistency that troubled 19th-century physicians. But the core therapeutic principles remain the same. We're not discovering cannabis medicine in 2026. We're rediscovering it.

What the Past Tells Us About the Future

Understanding the pre-prohibition history of cannabis medicine matters for the ongoing policy debates around rescheduling, medical access, and research. When federal authorities classify cannabis as having "no currently accepted medical use," they're contradicting nearly a century of the American medical establishment's own pharmacological history. When opponents of medical cannabis claim the concept is novel or unproven, they're ignoring a documentary record that stretches back to the 1850s.

The history also offers a cautionary tale about the relationship between politics and medicine. Cannabis wasn't removed from American medicine because doctors decided it didn't work. It was removed because politicians decided it was politically useful to prohibit it. The medical evidence was overridden by racial prejudice, bureaucratic self-interest, and media sensationalism—forces that, in different forms, continue to shape cannabis policy today.

As the cannabis rescheduling debate continues to stall at the federal level in 2026, it's worth remembering that we're not really arguing about whether cannabis has medical value. That question was answered—affirmatively—before any living American was born. The real question is whether we're ready to stop pretending otherwise.