In stark contrast to the exaggerated fears of the past, most people now believe cannabis is relatively harmless. While marijuana is less dangerous than other drugs, it is not without risks.

In a study published on January 5, my colleagues and I discovered that 59 percent of people using medical cannabis for chronic pain experienced moderate to severe withdrawal symptoms if they stopped consuming marijuana for hours or days.

The majority of states in the United States have legalized cannabis for medical use, and 15 have legalized it for recreational use. Cannabis is being used by an increasing number of people, particularly older adults, and the perceived harms of weed use are decreasing. While many people report therapeutic benefits or enjoy recreational cannabis use, it is critical that people understand the risks of cannabis use as well.

Cannabis withdrawal symptoms can include both physical and psychological experiences that occur when a person comes down from a high or goes without using for an extended period of time.

When people use cannabis on a regular basis, such as daily or nearly daily, certain parts of the brain become dependent on cannabinoids, the psychoactive chemicals found in cannabis. Cannabinoids are naturally produced in the body, but at much lower concentrations than those found in most cannabis products. Cannabinoid levels drop and withdrawal symptoms occur in those who do not use marijuana for several hours or days. Irritability, depression, decreased appetite, sleep difficulties, a desire or craving for cannabis, restlessness, anxiety, increased aggression, headaches, shakiness, nausea, increased anger, strange dreams, stomach pain, and sweating are some of the symptoms.

Cannabis withdrawal symptoms typically subside within one to two weeks of cessation of use as the body returns to its own natural production of cannabinoids. Cannabis withdrawal, unlike withdrawal from other psychoactive substances such as alcohol, is not life threatening or medically dangerous. However, it does exist. Cannabis withdrawal can also be quite unpleasant, and people may end up continuing to use cannabis – even if they want to cut back – just to avoid withdrawal symptoms.

Over the course of two years, my colleagues and I surveyed 527 people who were using medical marijuana for chronic pain to determine how common withdrawal symptoms are. We discovered that 59% of people who use medical cannabis for chronic pain experienced moderate to severe withdrawal symptoms. The most common symptoms were sleep difficulties, irritability and anxiety.

We also discovered that cannabis withdrawal symptoms were more severe in younger people, those with mental health issues, those with a longer history of cannabis use, and those who used it more frequently or in larger amounts. Furthermore, we discovered that smoking cannabis, rather than eating or applying it topically, was associated with worse withdrawal symptoms.

Our team also investigated how people’s withdrawal symptoms evolved over time. Over the two years of the study, most people experienced the same severity of withdrawal symptoms whenever they stopped ingesting cannabis, but about 10% – particularly younger people – got worse over time. Reducing the frequency or amount of cannabis used, as with most addictive substances, may help to alleviate these symptoms.

Our study focused on people who only use medical cannabis for pain relief. However, researchers discovered that 47 percent of frequent cannabis users experience withdrawal symptoms in another recent meta-analysis that included both recreational and medical use.

Cannabis isn’t the demon drug from “Reefer Madness,” but it’s also not a magical plant with infinite benefits and no drawbacks. As cannabis use grows in the United States, it’s critical that people understand that regular use can cause withdrawal symptoms and that they understand what those symptoms are.