Can You Use Cannabis for Cancer Pain?

Pain is one of the worst and most common symptoms of cancer. People with cancer are increasingly looking to medical cannabis for pain relief when traditional medications fail. But cannabis can also make some cancer treatments less effective. 

So is there evidence that medical cannabis is effective for cancer pain? And what are the risks? 

What are some benefits of cannabis for pain?

Cannabis, also known as marijuana, is a medicinal plant. Cannabis contains active compounds called cannabinoids. Human trials have shown that the two most common cannabinoids — tetrahydrocannabinol (THC) and cannabidiol (CBD) — may reduce inflammation and pain.

Pain is the most common symptom of cancer. Chronic pain affects both people who are fighting cancer and cancer survivors. Just like there are many types of cancer, there are also many types of cancer-related pain: 

• Cancer treatments like chemotherapy can cause nerve damage and nerve pain. 

• Surgeries can leave lasting painful damage. 

• Cancerous tumors themselves can cause pain. 

Opioids are a common treatment for cancer pain. However, these medications do not work for many people. That has led many people with cancer to try medical cannabis as another option for pain relief. Recent studies have found that between 24% and 40% of people with cancer in the U.S. use medical cannabis. 

There’s also evidence that cannabis could reduce the amount of opioids individuals take. Opioids have serious side effects like cognitive impairment and constipation. Cannabis could improve people’s lives by reducing the negative effects of opioids. However, not all studies have confirmed that cannabis can reduce opioid use.

Health Canada approved a medication containing both THC and CBD (called Sativex) for cancer pain in 2007. Here in the U.S., though, the FDA has not approved any cannabinoid drugs for cancer or cancer-related pain.

How does cannabis help reduce cancer-related pain?

Cannabis reduces cancer-related pain in many ways. Cannabinoids, the active compounds in cannabis, act on your endocannabinoid system (ECS). The ECS touches every organ in your body. This gives cannabis many ways to reduce cancer-related pain. We’ll go into some of these ways below.

Nervous system

Scientists are still debating how CBD fights pain in the body. They know that it’s partially because CBD affects many aspects of the nervous system. Your nervous system is a network of cells and organs that control many things, including how you feel pain. 

The nervous system includes your brain, spinal cord, and nerve endings in your skin. These organs communicate with each other by sending chemicals, called neurotransmitters, which bind to different targets called receptors.

When you take cannabinoids like THC and CBD, they interact with receptors in your nervous system. THC partially activates a type of receptor in your nervous system called the cannabinoid 1 (CB1) receptor. 

CB1 receptors are located in the sensory nerve endings in your skin that detect pain. They are also located in the areas of your brain that control how you feel pain and emotions. By activating CB1 receptors, THC causes a variety of changes in your nervous system, resulting in a decreased sensation of pain.

Inflammation

Your immune system causes inflammation — which looks like redness or swelling — when it thinks it is being attacked. Inflammation is necessary for your body to defend against viruses and repair damaged tissue. 

But inflammation can also create a feedback loop that increases pain. Cannabinoids are powerful anti-inflammatory compounds, so they can reduce inflammation and pain caused by inflammation.

Topical cannabinoids are lotions or balms infused with cannabis. They are designed to reduce inflammation in targeted areas where you feel pain. Laboratory research suggests that topicals can reduce inflammation. However, human studies have yet to widely confirm this.  

Mood

Your state of mind can directly change how you experience pain. For example, anxiety increases your perception of pain. And individuals with cancer dealing with chronic pain frequently experience mood symptoms like anxiety, depression, and suicidal ideation. 

Medical cannabis may reduce pain by improving these mood symptoms. Medical cannabis can reduce anxiety, potentially lowering feelings of pain. Medical cannabis has also been found to improve mental and physical health of those with chronic pain. 

One study found that people who took medical cannabis for 1 year had much lower feelings of depression and anxiety. They also had better sleep quality.

Sleep

Sleep has a close relationship with how we experience pain. Poor-quality sleep can increase the amount of pain you feel. And pain can reduce your quality of sleep. This can create a negative cycle that worsens pain symptoms.

There’s evidence that cannabis and cannabinoids like CBD can improve sleep quality. People with cancer who use medical cannabis frequently report that cannabis improves their quality of sleep. This could make cannabis helpful in reducing pain perception. 

Has medical cannabis been tested in clinical trials for cancer pain?

Clinical trials are the gold standard for evaluating any medical treatment. These trials compare the effects of new medications and treatments to a placebo in humans. 

Cannabis has mixed clinical trial results when tested for cancer pain. Here are some examples of how it has helped: 

• In one trial, high doses of THC outperformed codeine (an opioid) in relieving the painful symptoms of cancer. 

• In a separate trial, a combination of THC and CBD led to statistically significant reductions in pain compared to a placebo.

But other trials have found no benefits. Nabiximols (Sativex) is a medication containing THC and CBD. It has failed to reduce pain in recent large-scale trials. 

However, patient surveys have shown positive results. Many people who use medical cannabis believe that it effectively treats their cancer pain. A 2018 study on individuals who use medical cannabis for cancer found that the majority reported significant or moderate reductions in pain.

Limitations of clinical trials on cannabis in the U.S.

There are certain things to consider when looking at clinical trial data on medical cannabis:

• Cannabis is illegal. The U.S. Government has placed cannabis in the most dangerous class of illegal substances. This means that scientists must pay for special licenses to handle any medical cannabis. This makes it difficult to conduct clinical trials. And this means that less human testing has been done on cannabis compared to other promising medications.

• Legal cannabis is different from research cannabis. Clinical trials are also unable to use the same types of cannabis that are found in medical cannabis markets. The legal cannabis found in places like California or Michigan are significantly different from the pharmaceutical cannabinoid medications that researchers test during clinical trials. There is also a lack of cannabis available for clinical researchers.

What types of cannabis are best for soothing pain related to cancer?

Choosing a medical cannabis product can be a confusing process. There are countless different types of cannabis products. And cannabis contains more than 100 active compounds that come in a variety of different ratios.

The two most important things to consider are cannabinoid content and delivery route:

• Cannabinoid content: Every legal cannabis product should include a label showing its cannabinoid content. This is the amount of active compounds (like THC and CBD) inside the product.

• Delivery route: How you consume cannabis will change its effects. Inhaling cannabis is the fastest method, while eating edibles and oils takes longer to feel but will have a longer duration of effect. Topical creams can direct cannabis to specific painful parts of your body.

So what’s the best combo and method of using cannabis for you? Here are two things to consider if you want to use cannabis for cancer pain:

• A combo of CBD and THC could be best. Clinical trials have shown that a combination of CBD and THC is most effective for pain relief. For example, Health Canada’s recommended maximum daily dose of Sativex for cancer pain contains 32.4 mg THC and 30 mg CBD. You can replicate this dose with medical cannabis products that have been tested for purity.

• Inhaling and eating cannabis could be the best way. A recent study of people who use cannabis for pain relief found that a majority used inhaled forms of cannabis. Inhalation can be smoking cannabis, inhaling vaporized cannabis, or inhaling vaporized cannabis oil. The study found that those who use both inhalable products and non-inhalable reported the best outcomes for pain relief.

Does cannabis have any negative effects you should be concerned about?

Medical cannabis has far fewer negative side effects than the standard opioid painkillers prescribed for cancer pain.

But this substance is not harmless. Consuming cannabis has clear risks, including:

• Impairment: THC is a mind-altering substance that is dangerous when combined with activities like driving.

• Addiction: THC is an addictive compound. Some cannabis users experience cannabis use disorder, a substance use disorder associated with negative outcomes.

• Overconsumption: Consuming too much cannabis, especially foods infused with THC, can cause an overdose. Overdoses can cause discomfort, including panic attacks and rapid heart rate.  

• Lung health: Smoking cannabis increases the risk of a bronchitis-like cough.

• Drug interactions: THC and CBD have dangerous interactions with dozens of common pharmaceutical medications.

Should you ask your doctor about trying cannabis during your cancer treatment?

People with cancer should talk to their healthcare providers before trying medical cannabis. 

Using medical cannabis is a difficult choice for those with cancer. There are potential benefits but also potential disadvantages to using medical cannabis:

• It can interfere with some cancer treatments. Multiple studies have found that cannabinoids can interfere with some types of cancer-fighting treatments. For example, people taking a cancer therapy called immune checkpoint inhibitors along with cannabis might do worse compared to those who didn’t take cannabis. 

• But it might also fight cancer. Cannabis also has anti-tumor effects against many types of cancer, according to lab research. These studies have not been confirmed in human trials. But scientists have found that many types of cancer cells get smaller or die when exposed to cannabinoids inside a lab. Studies have also shown that cannabis can make some cancer treatments more effective.

The safest option is to speak with your healthcare provider about using medical cannabis. It may also be helpful to speak to a cannabis specialist. Nonprofits like the Society of Cannabis Clinicians can help you find a healthcare provider who specializes in medical cannabis.

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Written by:

Lester Black

Lester Black is an independent journalist. His work has been featured in Popular Mechanics, The Guardian, and FiveThirtyEight.com.

Reviewed by:

Adie Rae, PhD

Adie Rae, PhD, is a neuroscientist known for her extensive expertise on cannabis. She has been conducting peer-reviewed research about cannabis since 2004.

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