Homeopathy Against Cocaine? A Terrible Idea

Less than a month ago, the Spanish government launched an offensive to remove so-called “pseudotherapies”—including homeopathy—from both the public healthcare system and university curricula. In England, homeopathy has been gradually phased out of the National Health Service (NHS) since 2017; less than ten months ago, London’s largest homeopathic hospital was officially de-credentialed.

Back in 2015, the Australian National Health and Medical Research Council (NHMRC) concluded—after reviewing over 100 scientific studies—that homeopathy is ineffective, and that using it for serious or chronic conditions represents a significant risk to patients.

Despite this, and based on a single, questionable study, the city government of Itajaí (Brazil), together with the University of Vale do Itajaí (Univali), Brazil’s Federal Medical Council (CFM), and the Ministry of Health, has decided to treat drug addicts with homeopathic preparations.

Citing a paper by researcher Ubiratan Cardinalli Adler (Federal University of São Carlos), published in the Journal of Integrative Medicine, the city plans to launch a pilot program to treat crack and cocaine dependence using homeopathic dilutions of coca leaves and opium.

Extreme Dilution

Homeopathy was invented in the 18th century by German physician Samuel Hahnemann, at a time when medicine knew little about anatomy, infectious agents, or effective treatments. Compared to bloodletting, leeches, and purgatives, homeopathy seemed a gentler alternative.

It is based on two principles: “like cures like” and serial dilution. To make a typical homeopathic remedy, one identifies a substance that produces the same symptoms as the disease. For example: insomnia? Then use caffeine. The substance is then diluted over and over, under the belief that the more diluted it is, the more potent the “medicine” becomes.

A common dilution, “30C,” involves thirty rounds of diluting one part of active ingredient in 100 parts solvent. By the end, a single drop of the original material is dispersed in a number of solvent molecules greater than the total number of molecules in the observable universe. In other words: it’s just water.

The dilutions planned for use in Itajaí are “Q2” and “Q3.” Roughly speaking, that means one teaspoon of active ingredient in five Olympic swimming pools of water (Q2), or one teaspoon in the entire volume of Earth’s oceans (Q5). These sugar pills, sprinkled with such solutions, are what the city expects will help recover patients addicted to hard drugs. The project awaits funding approval from the Pan American Health Organization (PAHO), via Brazil’s Ministry of Health.

Scientific Consensus

The idea that such extreme dilutions could work is implausible. Claims about “water memory” have never been substantiated. If homeopathy were effective, it would require rewriting the basic laws of chemistry and physics.

And yet, because of its popularity, homeopathy has been extensively tested. And it has failed.

The Australian NHMRC review was only one among many systematic reviews and meta-analyses, all showing the same result: homeopathy performs no better than placebo. Apparent improvements are explained by patient expectation, conditioning, or the fact that many conditions—like mild viral infections or childhood ailments—resolve on their own.

The global scientific consensus is clear: homeopathy’s supposed efficacy is an illusion. And in countries with taxpayer-funded healthcare, a second consensus is emerging—that homeopathy is a waste of resources.

“Complementary”?

Despite this, Brazil’s Federal Medical Council officially recognizes homeopathy as a medical specialty. It is offered within the national health system (SUS) as one of several so-called “Integrative and Complementary Practices.”

Supporters argue that, even without proof, homeopathy brings well-being, reduces reliance on conventional drugs, and should be seen as a harmless complement to standard care. But the pilot project in Itajaí shows the danger of this logic: here, homeopathy is not offered as complementary, but as the only treatment for cocaine and crack addiction.

A “Nobel”?

The study used as justification for the program appeared in a low-quality journal dedicated to alternative medicine. As physician and researcher Edzard Ernst (University of Exeter, UK) remarked in his review of the paper: “Whoever develops an effective treatment for drug dependence deserves a Nobel Prize. Whoever proves that homeopathic dilutions work beyond placebo deserves one too.”

Groundbreaking findings would normally appear in top scientific journals—not in niche, third-tier publications read mainly by alternative medicine enthusiasts. The Adler study is riddled with methodological flaws.

Though labeled “double-blind,” the nurse administering the pills knew which patients were receiving homeopathy and which were receiving placebo. Dropout rates were extremely high, and the authors failed to account for this bias. Measures of drug craving intensity showed no difference between groups. While the frequency of craving episodes was lower in the homeopathy group, that same group also showed higher concurrent use of alcohol and marijuana—factors not evaluated in the study.

The authors even cite Jacques Benveniste’s infamous 1988 Nature paper on “water memory,” without mentioning that Nature itself later debunked the results as invalid due to methodological flaws.

Even the authors of the homeopathy–drug addiction study admit that high dropout rates and methodological issues limit the reliability of their results.

Why?

So why is Itajaí launching a program to treat such a serious condition with an unproven method, based on a deeply flawed study? And why do the Ministry of Health, Univali, and the Federal Medical Council endorse it?

It is true that treatments for cocaine and crack dependence are limited. But public investment should focus on approaches with at least minimal plausibility. Endorsing homeopathy as a valid option for serious conditions risks exactly what the Australian review warned against: that patients might view it as a replacement for real, evidence-based therapy.

History offers tragic reminders. In 2002, nine-month-old Gloria Mary Thomas died in Australia from untreated eczema—easily manageable with conventional medicine—because her father, a homeopath, insisted on treating her solely with homeopathy. She endured six months of suffering before her death.

Brazilian actress Dina Sfat was diagnosed with breast cancer in 1986. She rejected surgery and standard treatment, relying instead on homeopathy, acupuncture, and other alternative therapies. She died in 1989 after the cancer metastasized.

Many homeopaths would, in practice, refer such patients to conventional treatment. But once the practice itself is legitimized, how do you explain to a hopeful patient that it was all make-believe—that it doesn’t actually work?

✍️ Natalia Pasternak is a researcher at the Institute of Biomedical Sciences at the University of São Paulo (USP), national coordinator of Pint of Science Brazil, and president of the Instituto Questão de Ciência.