Pandemic panic has sparked sensational claims that cannabis cures covid-19, the disease caused by the novel coronavirus. On social media and in the advertisements of cannabis and CBD retailers, the idea that cannabis prevents or remedies covid-19 is spreading rapidly.

While medicinal cannabis and CBD increasingly have gained credibility as effective palliative treatments for anxiety, epilepsy and muscular dystrophy, the notion that cannabis “kills” or “resolves” the coronavirus or any other viral infections is bunk and flies in the face of current science. In fact, smokable and vape-able cannabis, which accounts for roughly 80 percent of legal sales in the United States, when consumed only compromises respiratory function and thus increases one’s susceptibility to contracting covid-19.

And yet, cannabis sales continue to grow alongside the popular misconception that it is once again a miracle cure for an epidemic disease. In the mid-19th century, physicians in France and across the West also made the claim that hashish provided a “heroic remedy,” as one contemporary physician put it, in the fight against the plague and cholera. They were wrong, of course, and patients — and the reputation of cannabis — paid the price.

Many believe that we currently live in the “golden age” of cannabis, given the many U.S. states that have legalized its use in recent years; however, the true heyday of medicinal cannabis in the West came and passed nearly two centuries ago, in the 19th century. During the 1830s and 1840s, pharmacists and physicians in Europe and its colonies developed numerous cannabis-based medicines, including edibles and tinctures, and used them to combat the era’s most feared, deadly and then misunderstood epidemic diseases, namely the plague and cholera.

One of the first Western physicians to experiment with cannabis as medicine was Irishman William Brooke O’Shaughnessy, a surgeon for the British East India Company and a professor of medicine in colonial Calcutta throughout the 1830s and 1840s. While in India, O’Shaughnessy concocted a crude tincture of “charas,” a Hindi word for the pressed resin of cannabis, commonly known today as “hash,” and used it to treat cholera, hydrophobia (rabies), rheumatism, tetanus and convulsive disorders.

Around the same time, French physicians working in North Africa likewise experimented with medicines made from cannabis resin, called “hashish” in the Arab-Muslim world. French doctors observed Egyptian doctors using hashish to treat a range of ailments and then adopted the drug into their own medical tool kits.

French physician Louis Rémy Aubert-Roche, head of hospitals in Egypt during the plague outbreak there in 1834-1835, became so convinced of its effectiveness against the scourge that he published a book on the subject in 1840. In the opening pages, Aubert-Roche reported that dawamesk, as they called it, dissolved in coffee and administered over several days effectively cured 60 percent of plague patients he treated in the hospitals of Alexandria and Cairo during the epidemic.

In the era before germ theory, doctors believed the plague was caused by “bad air” released from toxic and unhygienic environments — an idea known as “anti-contagionism.” And so doctors like Aubert-Roche saw hashish as a treatment for what he understood to be damage to the nervous system. “Hashish, a substance that acts upon the nervous system, has given me the best results” for the plague, he wrote. “I believe it is a drug not to be neglected.”

But Aubert-Roche was wrong, mistaking pain relief and illusory correlation for cure. His and others' calls to regard cannabis as legitimate medicine reverberated in French and Western medical circles for the next decade. And dozens of Western medical practitioners heeded these calls and devoted their energies to refining cannabis-based medicines and particularly hashish tinctures for the European market.

Doctors also believed that hashish could cure another dangerous disease, cholera. Much like the plague, cholera was then misunderstood by a majority of physicians as a disease of the central nervous and gastrointestinal systems. Understood as such, tincture of hashish thus appeared an appropriate treatment for cholera and its attack on brain and nerves. “I believe,” physician Alexandre Willemin confirmed to the Academy of Medicine in Paris, “that of all the remedies proposed against cholera there are none more effective than the active principle of Cannabis indica. I am indebted for life to this energetic substance."

Willemin convinced doctors in Paris to adopt hashish tincture as a treatment against cholera when there was an outbreak in December 1848. Convinced that hashish could excite the nervous system into action against the damaging effects of cholera, doctors across Paris prescribed hashish tincture to combat the disease during the early stages of the epidemic over the next two months.

But it didn’t work. By March, the “blue death” had killed nearly 7000 people in Paris, roughly 50 percent of those who became infected, and Parisian medical journals reported that hashish tincture produced inconclusive results at best. Well-known pharmacist François Dorvault wrote in March 1849 that, “during the invasion of this terrible scourge in Paris, four months ago, many doctors of the city’s hospitals used this substance according to the indications of Willemin. As the results obtained were questionable, haschischine was entirely put aside.”

When hashish tincture did nothing to prevent the “blue death” from killing nearly 20,000 Parisians by the end of the year, doctors lost faith in the once-heralded wonder drug, beginning its fall into disrepute, obsolescence and eventual prohibition.

We can learn much from this first rise and fall of cannabis in Western medicine during the middle 19th century. Misunderstandings and misinformation about pandemics have historically pushed societies to adopt measures that exacerbate rather than prevent the spread of infectious disease, a phenomenon called the “cobra effect.” Whether by endangering plague and cholera patients with ineffective treatments 200 years ago or compromising the respiratory function of those facing the threat of the coronavirus today, past and present claims that cannabis provides a miracle cure for epidemic disease have done much more to hurt than help public health.

And while cannabis purveyors may want to use this pandemic as an opportunity to promote the medicinal qualities of their products, they would be wise to measure their claims of the drug’s curative power so as to avoid a second obsolescence.