One in five Americans experiences chronic pain — a distressing reality that drives depression and opioid use. This widespread pain problem is sending people to medical cannabis dispensaries in droves, looking for relief.

But according to a new study, which reviewed 8,505 cannabis products sold by 653 dispensaries across the United States, tetrahydrocannabinol, or THC, concentrations are often twice or even three times too high for pain relief .

THC is the main psychoactive compound in marijuana, and high concentrations can create a “vicious cycle” of dependence, according to the study authors. Too much THC cause a person to develop tolerance to the drug's effects and can induce adverse mental health effects with potentially lasting consequences.

The findings were published Thursday in the journal PLOS ONE.

"The products offered online in dispensaries, which should be a reflection of what they have in their physical facilities, are mostly very potent and represent a risk for patients that seek medicinal effects, and also a risk for regular users in the long run," co-author Edgar Alfonso Romero-Sandoval, a researcher at Wake Forest Medicine, tells Inverse.

"Our data and others' scientific findings point out that there is no need for high potency products in medical realm. Medicinal programs should have more stringent parameters for their products."

THC concentrations are often too high for pain relief, claims a new study. Heath Korvola/ Getty Images

In the new study, researchers aimed to see how dispensaries are advertising THC and CBD to consumers, not what concentrations were actually present in the products.

The combed the web and recorded the concentrations of CBD and THC in 8,505 plant cannabis products provided by 653 legal dispensary websites in California, Colorado, Maine, Massachusetts, New Hampshire, New Mexico, Rhode Island, Vermont, and Washington.

They predicted advertising strategies for medicinal and recreational marijuana would be similar, and "weren't really surprised" by the dramatic overlap.

"We have seen anecdotal information on how rewarded high potency cannabis products are in the recreational realm," Romero-Sandoval says. "We have seen consistent increases in potency over the years in the illegal market. So, we were expecting that something like this was happening."

It turns out, between 70 to 90 percent of the legal marijuana products offered in medical dispensaries had over 15 percent THC.

That percentage is much stronger than what clinical studies have indicated works for chronic pain relief — between 5 to 10 percent THC.

Some medicinal dispensaries went all the way up to 35 percent THC, while recreational dispensaries advertised up to 45 percent THC.

Along with high levels of THC, medicinal products also advertised relatively low concentrations of CBD, about 2 percent. Recreational dispensaries advertised even lower concentrations, about 1.3 percent CBD.

This trend is "concerning," the authors write, because CBD has the potential to curb some of THC's potentially negative psychological effects. But if the ratios are out of wack, CBD won't be able to help. (The claim that CBD can counteract THC is also debated by researchers.)

When they compared dispensaries operating in different states, they didn't see any stark differences. Across the board, medicinal and recreational dispensaries offer stronger products than is recommended for chronic pain.

The problem with all that extra THC is it can heighten the risk of adverse side effects, and may even increase pain.

It can also lead people to need more and more marijuana to take the edge off, a habit that can lead to high tolerances and dependence, the study claims.

"Cannabis is less addictive than other drugs such as cocaine or opiates, but it is addictive at a certain degree if used regularly and if its use started at younger ages," Romero-Sandoval says.

At this stage, researchers don't know exactly how addictive these high potency products are. It's expected, Romero-Sandoval explains, that the higher the concentrations of THC, the higher the risk of developing tolerance and addictive disorders .

With this new data on how dispensaries are advertising THC and CBD, the researchers hope regulators will craft regulations that "protect patients" using medical marijuana, and prevent the misconception that high potency cannabis is safe to treat pain, the researchers write.

"Better regulation of the potency of medical marijuana products is critical," Romero-Sandoval says.

"The FDA regulates the level of over-the-counter pain medications such as ibuprofen that have dose-specific side effects, so why don't we have policies and regulations for cannabis, something that is far more dangerous?"

"This is a great opportunity to set the foundations of a safer cannabis program framework that can serve as a model for other states or countries that are considering legalizing marijuana."

Abstract: Cannabis related online searches are associated with positive attitudes toward medical cannabis, particularly when information is obtained from dispensaries. Since pain is the main reason for medicinal cannabis use, information from dispensary websites has the potential to shape the attitude of pain patients towards cannabis. This is relevant because cannabis has demonstrated efficacy in neuropathic pain with low tetrahydrocannabinol (THC) concentrations (< 5-10%), in contrast to potent cannabis (>15% THC), which is highly rewarded in the recreational realm. The role of CBD in pain is not clear, however it has gained popularity. Thus, we hypothesize that the potency of medical cannabis that is advertised online is similar to the cannabis advertised for recreational purposes, which would potentially create a misconception towards medical cannabis. The current lack of knowledge surrounding advertised potencies in the legal cannabis market limits the ability to generate clear policies regarding online advertising to protect patients that are willing to use cannabis for their condition. Thus, we evaluated the advertised THC and CBD content of cannabis products offered online in dispensaries in the United States to determine products’ suitability to medicinal use and compare the strength of products offered in legal medical and recreational programs. We recorded THC and CBD concentrations for all herb cannabis products provided by dispensary websites and compared them between or within states. Four Western states (CA, CO, NM, WA) and five Northeastern states (ME, MA, NH, RI, VT) were included. A total of 8,505 cannabis products across 653 dispensaries were sampled. Despite the clear differences between medicinal and recreational uses of cannabis, the average THC concentration advertised online in medicinal programs was similar (19.2% ±6.2) to recreational programs (21.5% ±6.0) when compared between states with different programs, or between medicinal and recreational programs within the same states (CO or WA). Lower CBD concentrations accompanied higher THC products. The majority of products, regardless of medicinal or recreational programs, were advertised to have >15% THC (70.3% - 91.4% of products). These stated concentrations seem unsuitable for medicinal purposes, particularly for patients with chronic neuropathic pain. Therefore, this information could induce the misconception that high potency cannabis is safe to treat pain. This data is consistent with reports in which THC and CBD in products from legal dispensaries or in nationwide products from the illegal market were actually measured, which indicates that patients consuming these products may be at risk of acute intoxication or longterm side effects. Our study offers grounds to develop policies that help prevent misconceptions toward cannabis and reduce risks in pain patients.