Cannabis Laws Linked to Lower Opioid Use in Cancer Patients

Study findings on cannabis laws and opioid use

Cannabis laws have been changing in the United States in recent years, with many states now legalizing or decriminalizing recreational or medicinal cannabis use. As such, cannabis is legally available in dispensaries, which have increased in number over the years.

Opioids are a commonly prescribed medication for people with cancer to help manage pain, a symptom that reportedly affects over 65% of people with this diagnosis. ^[1]

A new study (Lozano-Rojas et al, 2025) investigated whether there is an association between the growing number of cannabis dispensaries and a reduction in cancer-related opioid use, using a cross-sectional study design to gather data relating to a mean of around 3 million individuals. ^[1] Results of the study indicated significant reductions in opioid prescriptions after the opening of both medicinal and recreational cannabis dispensaries, as follows: ^[1]

These results suggest that cannabis may be an effective alternative for cancer-related pain management. However, there are limitations to the study. As such, further research into this topic is required, including the impact of individual, prescriber, and policy aspects. ^[1]

Why cannabis may reduce opioid needs

People with cancer-related pain may not require as much opioid pain relief if they use cannabis as an alternative or adjunctive analgesic. In particular, people with low-level pain might find that cannabis manages their pain symptoms effectively, without causing the same side effects as opioids. ^[1][2] This allows for more functional pain management, which is appealing to people who work or want to continue other aspects of their daily lives without as many disruptions.

Additionally, cannabis can provide a sedating and euphoric effect. This can not only help with the management of pain but also may assist with managing other cancer-related symptoms and treatment effects, such as anxiety and difficulty focusing. Because of this, people using cannabis may feel that they do not require opioids or can manage with reduced doses. ^[3]

Potential benefits of cannabis for cancer patients

Cannabis could be of potential benefit for cancer patients, including: ^{[1][3][4][5][6]}

• Pain relief: Cannabis can be effective at managing cancer-related pain when used as an adjunctive or substitute treatment. It is known to create anti-inflammatory effects, which can also help to reduce or manage pain. Cannabis may be particularly helpful for people who experience negative effects from opioid medications or those with low-level pain. 
• Antiemetic effects: Research suggests that cannabis can be an effective treatment for chemotherapy-induced nausea and vomiting. For example, one study (Tramèr et al, 2001) found cannabinoids to be more effective than a range of other antiemetics at managing nausea and vomiting in people receiving chemotherapy.
• Antitumor properties: Some limited research suggests that cannabis may help to reduce the size or slow the growth of tumors. The evidence for this is currently insufficient to promote its use for this purpose, and there are ongoing studies to further investigate this.
• Lower risk: Prolonged opioid use can result in dependence and addiction, which may have more severe outcomes than those of prolonged cannabis use. Additionally, opioids can cause side effects such as constipation, confusion, and delirium, which may lead to unpleasant or dangerous outcomes. Using cannabis to replace opioid treatment can help reduce these risks. 
• Other benefits: Cannabis could also help cancer patients by improving mood issues, anxiety, appetite, and insomnia.

Risks and limitations to consider

Potential risks and limitations of cannabis use among cancer patients could include:

• Development of cannabis use disorder: Prolonged use of cannabis may increase the risk of developing cannabis use disorder or cannabis dependence. However, research suggests that the risk of long-term use leading to cannabis dependence is around 9%, which is significantly lower than other substances, including heroin, alcohol, and cocaine, although this increases to 25-50% among daily users. ^[4][7]
• Interactions with treatment: Cannabis could interact with cancer treatments such as chemotherapy, potentially worsening treatment-related cognitive issues or impacting the effectiveness of the treatment, although this has not been extensively studied. ^[8]
• Negative effects: Adverse effects can occur with cannabis use, and these may vary depending on the individual. For example, cannabis can cause sedation, euphoria, low mood, anxiety, and paranoia. ^[4][7] Any of these can be considered undesirable depending on the person and the effect they are hoping to produce.
• Individual differences: People can respond differently to cannabis, and some may not tolerate the range of effects it can cause. People who have not used cannabis before may be more susceptible to unpleasant effects. For some people, it may be unsuitable, particularly people with a history of psychotic symptoms, as cannabis may exacerbate or trigger these conditions. ^[6][7]

Policy and public health implications

It is important for people to be aware of the different laws and regulations around recreational and medicinal cannabis use within their state, as these vary significantly across the country. Where use is permitted, it may be beneficial to discuss with a medical professional how to use it safely, including dosing and frequency recommendations. 

Guidance for patients and caregivers

It can be helpful to consider using gradual dose increases when starting to use medicinal or recreational cannabis. This can allow you to learn how it affects you and recognize any adverse effects it may cause.

Anyone wishing to utilize cannabis to assist with managing pain or other cancer-related symptoms should first discuss this with their physician to gain a better understanding of the risks and benefits and how it may impact their treatment.