A recently published retrospective study suggests medical cannabis reduces neuropathic pain without serious side effects.

Algea Care, Europe’s leading telemedicine platform for medical cannabis, conducted the study in cooperation with the University Medical Center Hamburg-Eppendorf.

Published in the journal Medical Cannabis and Cannabinoids, CLN sat down for a chat with the CEO of Algea Care, Dr. Julian Wichmann, who was also instrumental in the study’s design.

 “While the study looked at it retrospectively,” says Dr. Wichmann, “Does [medical cannabis] work and the answer is, yes, it works.”

Details of the Medical Cannabis Reduces Neuropathic Pain Study

How did this study discover that medical cannabis can reduce neuropathic pain? One way was having patients report their “pain score.” At the start of the treatment, 96% said a pain score of 6 out of 10, with 10 being the most pain.

However, within six weeks of beginning medical cannabis, the reported reduction in pain score was significant. The average pain score went from 7.5 to 3.75.

Follow-up consultations with their doctor found that 90% of the patients reported reduced neuropathic pain. Over six months, 99% would eventually report improvement in their general condition.

No patient reported severe adverse effects. Patients reported dry mouth (5.4%), tiredness (4.8%), and increased appetite (2.7%).

“I think the observation data in the study that we published is crucial,” says Dr. Wichmann. “Because it shows cannabis is extremely safe and comes without any severe side effects.” Adding that the side effect of tiredness is something patients with neuropathic pain welcome. 

Dr. Wichmann says sleep disorders are typical in patients suffering from pain.

So when you see these patients as a doctor, you don’t only treat them for pain; you have to treat them for a sleeping disorder, and you know traditional medicine often means at least two separate medications. Something against the pain or maybe multiple medications, but also something to help them sleep. What we saw here was that the single medication, cannabis, works well to help with both neuropathic pain but also sleeping disorders.

What About Stigma?

Like in Canada or the U.S., German doctors are hesitant about prescribing medical cannabis, whether for neuropathic pain or sleep.

“The reality of it is that probably only two percent of doctors have ever treated a patient with cannabis.”

Dr. Wichmann says stigma is what prevents many doctors from acting. However, he expects studies like this (and future ones) will turn the tide. As well as broader legalization efforts.

Still, having pharmacies dispense medical cannabis is a novel concept.

“I think there’s a stigma, but we see a lot of improvement there and therefore also see a lot of referrals of cannabis treatment,” says Dr. Wichmann.

The European Union and international obligations have curtailed Germany’s legalization efforts. Instead of broad commercial legalization, like Canada’s, the Germans will take a more low-key approach, emphasizing community gardens and non-profit cannabis clubs. 

Canada had developed a similar medical cannabis system, often called “compassion clubs.” But this wasn’t a state-approved program. Since legalization, authorities have been attempting to eradicate these grassroots efforts in favour of large corporate cannabis conglomerates.

Dr. Wichmann answered negatively when asked about illicit markets in Germany and whether medical patients have to find relief there. 

German (and European) health care compared to North American health care couldn’t be further apart. “We’re in an interesting situation,” says Dr. Wichmann, “where out-of-pocket cannabis from the pharmacy is already cheaper than the illicit market.”

While medical cannabis stigma exists in Germany and Europe, it’s nothing like in parts of North America, where neuropathic pain is treated with conventional medicines.

“I think that’s typical for the German health care system understanding if there’s any reason for you to take cannabis to treat even, you know, mild to moderate sleeping disorder, medical will be safe.”

What About Psychosis?

Health authorities in North America would rather discuss cannabis-induced psychosis than medical cannabis benefits like reducing neuropathic pain. 

But as Dr. Wichmann points out, 

There’s data showing that the number one risk for developing cannabis-induced psychosis is you have a history of psychosis, maybe even your family history, and dosage, of course, makes a big impact.. if you control for these and that’s what you can do in a medical environment, not only is it an extremely safe medication, we’re seeing that it has fewer side effects than traditional medication.

So long as your medical cannabis:

1. Comes from a pharmacy, so there’s a guarantee of quality control.
2. You’re communicating with your doctor (“Even if it’s just a video called every four to six weeks,” says Dr. Wichmann)
3. It is medicinal. You’re not self-diagnosing your condition but seeing a medical doctor who can control for things like susceptibility to psychosis or cardiovascular issues that cannabis may complicate.

Of course, the study suggesting medical cannabis reduces neuropathic pain is only the beginning. As cannabis is normalized, Dr. Wichmann expects future research opportunities. 

“Millions would benefit from cannabis to treat their symptoms,” he says. And thanks to changing German laws, it’ll be easier for doctors to prescribe it medicinally. 

In brief: Legal cannabis gets tested for heavy metals in most states. That’s good because we know weed sucks up metals from the ground. And now, researchers have published a link between cannabis use and metal exposure among a group of smokers from 2005 to 2018. Read the details below.

By Nate Seltenrich

What’s in McGraw’s marijuana metal study of 2023?

Cannabis sativa is what scientists call a hyperaccumulator. Plants in this class, of which there are more than 700 (other members include sunflowers, barley, and tobacco) accumulate metals from soil, water, and fertilizers at levels hundreds or thousands of times greater than average. But a new study suggests some of those metals may also be accumulating in the bodies of cannabis users—arguably driven by contamination in the illicit markets.

Researchers with New York’s Columbia University sifted through a massive database from the US Centers for Disease Control’s long-running National Health and Nutrition Examination Survey to determine whether cannabis users had higher levels of any of 17 different metals in their blood or urine. They analyzed data from 2005 to 2018 representing 7,254 participants who reported on their diet, health, demographics, and drug use, and provided single blood and urine samples.

The researchers couldn’t tell what kind of weed was used, where it came from, or even where participants lived. However, they did adjust for other factors that affect exposure to and excretion of metals, including race/ethnicity, age, sex, education, and seafood consumption.

Among the study group, researchers found that cannabis-only users had on average 27% higher levels of lead in their blood than non-users of both cannabis and tobacco. Furthermore, cannabis-only users had 21% more lead in their urine than those who abstained. Researchers also found elevated levels of cadmium in cannabis users, even controlling for tobacco use. Weed-only partakers in the study set had 22% more cadmium in their blood than the average abstainer.

These findings reinforce why legal states require that cannabis be tested for metals. Failed batches must be destroyed or remediated, and states routinely conduct recalls on any mistakenly released products that fail subsequent safety testing. The streets do not issue recalls. In June and July 2023, Oregon recalled flowers testing hot for cadmium, mercury, and arsenic.

Legal tobacco contamination is worse than illicit cannabis

Minute amounts of either lead or cadmium can affect human health. The US Environmental Protection Agency considers any lead exposure dangerous and has classified cadmium as a probable human carcinogen.

None of the other 15 elements evaluated in the study—including arsenic, cobalt, manganese, and mercury—showed a clear causal association with cannabis use. And tobacco users proved far worse off. Their urinary cadmium levels were three times higher than those of exclusive cannabis users, for example, while their blood lead levels were 26% higher. 

Exclusive tobacco use was also associated with elevated levels of antimony, barium, tungsten, and uranium. (Legal cannabis generally undergoes far more stringent testing than tobacco.)

Study ‘a tremendous contribution’

The study appeared in late August in Environmental Health Perspectives, an open-access journal published through the United States National Institutes of Health.

It stands out as one of very few to date to look at real-world associations between cannabis use and exposure to environmental contaminants, says Maxwell Leung, an assistant professor of pharmacology and toxicology at Arizona State University who has researched cannabis contaminants but was not affiliated with the new study. 

“It’s a tremendous contribution to our understanding of this public health issue.”

Yet the research’s relevance to ongoing exposures is somewhat unclear. That’s because the study period of 2005 to 2018 represents a time when few Americans had access to cannabis screened for safety by a certified testing lab.

Today nearly half of Americans live in a state where adults can buy legal weed tested for pesticides, solvents, microbes, and metals. In many of these states—including California, the nation’s largest legal marijuana market since sales began in January 2018—cannabis flower must contain less than 0.5 parts per million (ppm) lead and 0.2 ppm cadmium.

But the fact is that most smokers still are not buying from tested sources – and in some legal states the illicit market reigns. In the country’s biggest market, California, an estimated two out of three cannabis dollars are spent in the illegal market where growers don’t test for anything.

Next steps: Test legal vs. illegal weed exposures

More research is required to sort all this out, says Robert Thomas, a Maryland-based analytical chemist, and cannabis testing consultant who was not affiliated with the research. 

“Two of the most toxic elements known to mankind showed up in the blood and urine of regular cannabis users. I think that tells us something,” he said. “But we need to look at more data, we need to look at different subsets, and we need to look at different states, to see if there’s any difference.”

Senior author Tiffany Sanchez, an assistant professor of environmental health sciences at Columbia University, said a follow-up study comparing blood metals among cannabis users by state is already in the works. Her group also intends to look at metal contamination of untested CBD products.

“[Cannabidiol] is federally legal, but it’s not regulated by the FDA or the USDA,” Sanchez says. “So the big question I have is, how clean is it?”

Another new paper confirms lead and cadmium aren’t the only contaminants consumers of untested cannabis should be concerned about. 

Published in the Journal of Cannabis Research in August, it reports that among 24 samples of illicit cannabis seized by Canada authorities, 22 tested positive for pesticide residues. Police found 23 different chemicals in 22 samples, with an average of 3.7 pesticides per sample—some at strikingly high levels.

… the 92% detection rate in illegal cannabis is appalling.

Maxwell Leung, assistant professor of pharmacology and toxicology, Arizona State University

However, among 36 samples of licensed cannabis tested only two contained chemical residues: A single hit each for the fungicide myclobutanil and the herbicide dichlobenil, both at very low levels.

It’s another case of buyer beware, says Leung. 

“I believe this is the only study in the literature so far to compare pesticide contaminants in legal versus illegal cannabis. Although the sample size is small, the 92% detection rate in illegal cannabis is appalling.”