Medical Cannabis and Arthritis: What Does the Research Say?

Summary

Medical cannabis contains a plethora of compounds with anti-arthritic properties, helping reduce joint and bone pain and inflammation and increasing the range of movement in those with arthritis. Even though the evidence for cannabis’ efficacy in the treatment of arthritis is compelling, there are few clinical trials to definitively state that medical cannabis helps manage arthritis.

Introduction: What is Arthritis?

Arthritis is a common condition that causes pain, stiffness, and inflammation in a joint or joints. Osteoarthritis (OA) is the most common form of arthritis and is caused by the breakdown of cartilage, a rubbery material that eases the friction in your joints. Osteoarthritis most commonly affects the fingers, thumbs, knees, toes, spine, and hips but can affect any joint. Osteoarthritis tends to affect older people.

The other type of arthritis is rheumatoid arthritis (RA), an autoimmune disease where the immune system attacks the joints and causes joint pain, stiffness, swelling, and decreased movement of the joints. RA most commonly affects small joints in the hands and feet but can affect any joint/s.

It is unclear what triggers rheumatoid arthritis, but you are at increased risk if you have a family history of rheumatoid arthritis, are female, or smoke. You are more likely to develop arthritis if you suffer from another autoimmune disease (e.g., an IBD like Crohn’s, lupus, or psoriasis). The typical onset age for rheumatoid arthritis is 40 to 60 years old. Still, it can affect people of any age with juvenile idiopathic arthritis (JIA) or juvenile rheumatoid arthritis.

Complications of any type of arthritis include:

  • Progressive weakening of the joints and bones, causing significant pain, loss of balance, stiffness, and disability over time.
  • Carpal tunnel syndrome.
  • Inflammation in other body areas, such as the lungs, eyes, and heart.
  • Difficulties with movement can make it difficult to exercise, leading to metabolic syndrome, a combination of diabetes, high blood pressure (hypertension), and obesity.
  • An increased risk of heart attack and stroke.

Around 1 in 4 (23.7%, or 58.5 million people) adults in the U.S. have doctor-diagnosed arthritis. Common medications include analgesics like acetaminophen (Tylenol, paracetamol), NSAIDs such as ibuprofen, steroids such as prednisone, antibiotics, and disease-modifying anti-rheumatic drugs (DMARDs) such as azathioprine (purine synthesis inhibitor) and chloroquine (IL-1 receptor suppressor and anti-malarial). In advanced cases of arthritis, opioids may be prescribed to manage chronic pain. Herbal medications like turmeric and components like curcumin control inflammation in those with arthritis.

Arthritis is often mistaken for another condition called “osteoporosis.” Osteoporosis develops due to decreased bone mass and density, which previous injuries can cause, a family history of osteoporosis, long-term use of steroids, aging, low physical activity, low calcium intake, gastrointestinal surgery, eating disorders, and low body mass index (BMI). Osteoporosis can result from arthritis if you don’t get the physical activity you need to keep your bones strong. Still, arthritis is specifically noted for swelling, pain, and inflammation in the joints. Osteoporosis and arthritis are considered rheumatic diseases, many of which are autoimmune and inflammatory.

old woman holding and pinching her palm

Why Might Medical Cannabis Help Manage Arthritis?

There is increasing evidence that endocannabinoid system (ECS) dysregulation is involved in different types of inflammation. Cannabinoid receptor 2 (CB2, which is found in the immune system) plays a role in the pathophysiology of various autoimmune diseases, including rheumatoid arthritis. Endocannabinoids have also been shown to block the progression of joint inflammation in rodent models of arthritis.

ECS dysregulation, stress, and inflammation play a role in osteoarthritis and rheumatoid arthritis. The endocannabinoids anandamide (AEA) and 2-arachidonoylglycerol (2-AG) were identified in the synovial fluid of both OA and RA patients. In contrast, people without arthritis do not have endocannabinoids in their synovial fluid (a thick, protective liquid between your joints). Patients with RA also display more CB2 receptors in the synovial tissues from rheumatoid joints than in osteoarthritis joints.

This suggests that a selective CB2 receptor agonist could be a therapeutic target for those with arthritis. Both tetrahydrocannabinol (THC) and beta-caryophyllene have been shown to act as a partial or selective agonist at CB2 receptors. Cannabidiol (CBD) has also been shown to act as an anti-inflammatory in arthritic patients by increasing intracellular calcium levels, and CBD may also enhance bone healing.

Another reason why medical cannabis may help manage rheumatoid arthritis, in particular, is because it may help regulate the gastrointestinal tract and work with gut bacteria to help maintain a healthy gut. There is a theory that a dysregulated gut-joint axis is the cause of rheumatoid arthritis, as mice with RA have been shown to have alterations in the composition of microbial flora in their gut. It is suggested that an inflamed gut increases gut permeability, allowing activated intestinal immune cells to spread to the joints. At the moment, this is just a theory, but an interesting one considering that many health problems are associated with dysbiosis (a disruption to the microbiota homeostasis caused by an imbalance in the microflora, changes in their functional composition and metabolic activities, or a shift in their local distribution).

Medical cannabis can also help reduce reliance on opioid-based pain medications and even over-the-counter (OTC) pain medications like ibuprofen. CBD could also help reduce steroid intake as well, on top of providing similar anti-inflammatory benefits. Other potential benefits include increased activity levels due to the pain reduction aspects that medical cannabis confers, which can help further reduce inflammation. An improved, flavonoid-rich diet can also help reduce stress and inflammation – things that can make arthritis worse. Medical cannabis can help improve appetite.

Key Information and Takeaways

Arthritis + Rheumatoid Arthritis

  • Total Studies = 63
  • Positive Studies = 58
  • Inconclusive Studies = 5
  • Negative Studies = 0
  • 42 Meta-Analyses (39 positive, 3 inconclusive); 12 Animal Studies (11 positive, 1 inconclusive); 2 Double-Blind Human Trials (1 positive, 1 inconclusive); 7 Lab Studies (all positive)
  • 23 studies include CBD (21 positive, 2 inconclusive); 17 studies include THC (15 positive, 2 inconclusive); 1 study includes CBC (positive); 2 studies include CBG(both positive); 1 study includes CBDA (positive); 1 study includes THCA (positive); 5 studies include a CBD:THC ratio of 1:1 (all positive)
  • Possible Overall Efficacy: Moderate

Arthritis (Osteoarthritis)

  • Total Studies = 27
  • Positive Studies = 25
  • Inconclusive Studies = 2
  • Negative Studies = 0
  • 16 Meta-Analyses (15 positive, 1 inconclusive); 9 Animal Studies (8 positive, 1 inconclusive); 2 Lab Studies (both positive)
  • 8 studies include CBD (7 positive, 1 inconclusive); 4 studies include THC (3 positive, 1 inconclusive); 1 study includes CBC (positive); 1 study includes CBDA (positive); 1 study includes THCA (positive); 2 studies include anandamide (both positive); 1 study includes 2-AG (positive)
  • Possible Overall Efficacy: Moderate

Rheumatoid Arthritis

  • Total Studies = 40
  • Positive Studies = 36
  • Inconclusive Studies = 4
  • Negative Studies = 0
  • 28 Meta-Analyses (25 positive, 3 inconclusive); 3 Animal Studies (all positive); 2 Double-Blind Studies (1 positive, 1 inconclusive); 7 Lab Studies (all positive)
  • 16 studies include CBD (14 positive, 2 inconclusive); 14 studies include THC (12 positive, 2 inconclusive); 1 study includes CBC (positive); 1 study includes CBG (positive); 5 studies include a 1:1 THC:CBD ratio (all positive); 5 studies include anandamide (all positive); 4 studies include 2-AG (all positive)
  • Possible Overall Efficacy: Moderate

Some Leafwell Data

  • No. of Leafwell Patients certified for arthritis or rheumatoid arthritis in 2021 = 1,134
  • 462 patients used medical cannabis for joint pain, with an average reduction in pain of 38%.
  • 152 patients used medical cannabis for joint pain, including muscle and bone pain, with an average reduction in pain of 33%.
  • Many medical cannabis users saw an improvement in gripping, bending, pulling, pushing, sitting, and standing pain — a reduction of up to one-third.

Potentially Useful Cannabis Compounds

Cannabinoids

All of these cannabinoids have anti-inflammatory properties that may help reduce pain and inflammation in those with arthritis.

Terpenes

Many terpenes have anti-inflammatory properties that could help reduce inflammation in those with arthritis.

Flavonoids

Flavonoids have been shown to have anti-inflammatory properties and could be used to regulate the immune system.

Potential Pros

  • Cannabis has been shown to treat arthritic pain associated with inflammatory, nociceptive, and neuropathic pain.
  • CBD, in particular, could be anti-arthritic and help repair old bones.
  • CBD oil may act as an anti-inflammatory and “lubricant” for joints affected by arthritis.
  • Rheumatoid arthritis is an autoimmune disease. Cannabinoids may be able to help dampen an overactive immune system due to their immunomodulatory effects.
  • Medical cannabis can help relieve arthritic pain, insomnia, and anxiety.
  • Medical cannabis’ pain-relieving and anti-inflammatory effects may help arthritic patients with walking, gripping, pushing, pulling, twisting, and gripping.

Potential Cons

  • There is no definite proof of efficacy in humans yet, as most evidence is primarily anecdotal, based on animal studies, or includes studies with small population samples or with a high potential for bias.
  • There is some indication that osteoarthritis requires different cannabinoid ratios to rheumatoid arthritis to be effective, and we have not figured out which ratios are most helpful as of yet.

Conclusion

Despite most current evidence showing that medical cannabis may be effective for managing pain, inflammation, and joint problems, few clinical trials show that this is the case. Another potential problem is that, even if medical cannabis helps reduce arthritic pain and inflammation, it may not be clinically effective (i.e., more effective than current treatments). On the other hand, medical cannabis is often more tolerable — and certainly generally safer — a medication compared to most other prescription medications, even if other medications are just as effective. The current evidence suggests that medical cannabis certainly has a place in managing arthritis symptoms, particularly arthritis arising from another autoimmune disease.