Can patients use medicinal cannabis with other pain medications?

Chronic pain is a complex and challenging condition that affects millions of people worldwide. Managing chronic pain can be difficult for both patients and healthcare providers, especially when dealing with other conditions and potential interactions between different pain medications.

In recent years, medicinal cannabis has emerged as a potential natural alternative for chronic pain management, offering promising results in providing pain relief for some patients.

Let’s explore the potential benefits and risks of using medicinal cannabis with other pain medications, and discuss how to safely incorporate medicinal cannabis into your patient’s pain management plan.

What is chronic pain?

The International Association for the Study of Pain (IASP) defines chronic pain as pain that lasts for more than 12 weeks. Unlike acute (short-term) pain, chronic pain can persist even after the initial issue is treated. Chronic pain is complex and can be caused and influenced by many factors, including injury, illness, and underlying medical conditions.

Chronic pain affects about 20% of adults worldwide. For people with chronic pain, it’s typical for them to experience more than one type, for example, people may have a chronic pain condition like fibromyalgia and chronic back pain at the same time.

In addition to feeling the physical effects of pain, many chronic pain patients will have their symptoms amplified or influenced by their mental health. Over 67% of people with chronic pain also live with a mental health issue, such as major depressive disorder or generalised anxiety disorder.

Why is chronic pain so difficult to manage for some patients?

For many patients looking to manage their chronic pain, it can be difficult to know where to start, which medications they should use, and what medications they cannot mix. 

Before turning to a healthcare provider or experienced doctor for support, many patients may not know how to manage their condition. Some of the reasons why patients may struggle to manage their condition include: 

• Managing multiple medications: Chronic pain often has comorbidities (other conditions happening at the same time). People with chronic pain may also live with other conditions, like hypertension, diabetes mellitus, tuberculosis, depression, anxiety or arthritis — all of which may have different medication schedules that may not interact well with certain pain medications.
  
  Managing multiple conditions alongside chronic pain effectively can be challenging as practitioners need to address the larger picture of a patient’s overall well-being. When treating a patient who is managing multiple medications, it’s important to look at your patient’s health history and their goals holistically to ensure safe pain management.
  
  
• Chronic pain is unique to everyone: The exact experience of chronic pain can vary greatly from person to person. This means that management strategies need to be tailored to each patient. Some factors that affect how pain is felt and processed in the body include genetics, past experiences with pain, and psychological well-being.
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• Multiple causes: There isn’t just one cause of chronic pain. Chronic pain can have various underlying causes and can have physical, psychological, and environmental factors, making it challenging to pinpoint a single cause for treatment.
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• Growing tolerance: Long-term use of some pain medications, including opioids and NSAIDs, can lead to tolerance, where higher doses are needed to achieve the same pain relief.
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• Avoiding side effects and dependency: Some pain medications, including opioids and NSAIDs, carry the risk of side effects and/or addiction, making them less ideal for long-term management.
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• Limitations of current treatments: While there are various treatment options available for chronic pain, not all patients respond the same way to these treatments. Some individuals may find relief with one approach, while others may not experience significant improvement.

Due to the complicated nature of chronic pain, a comprehensive approach is often required to manage the condition effectively. This may involve a combination of medical treatments, physical therapy, psychological support, lifestyle modifications, and patient education.

Common pain medications for chronic pain and how they work?

There are several types of pain medications used to manage chronic pain which work in different ways to relieve pain.  Some common types of pain medications for chronic pain include:

• Nonsteroidal Anti-Inflammatory Drugs (NSAIDs): NSAIDs, such as over-the-counter ibuprofen (Nurofen), naproxen, and aspirin, are commonly used to reduce inflammation and provide pain relief. They work by inhibiting the production of prostaglandins, which are chemicals in the body that promote inflammation, swelling, and pain. NSAIDs are particularly effective for musculoskeletal pain, such as arthritis and low back pain.
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• Paracetamol: Over-the-counter paracetamol (or brand name Panadol) is a pain reliever that is often used to manage mild to moderate pain. Unlike NSAIDs, paracetamol does not have anti-inflammatory properties, so it is more suitable for pain that is not caused by inflammation. While paracetamol is widely used, scientists aren’t sure exactly how it works — though it may take effect by reducing pain signals in the brain.
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• Opioids: Prescription opioids, such as codeine, oxycodone, hydrocodone, morphine, and fentanyl, are powerful pain medications that are used for moderate to severe chronic pain. Opioids work by binding to specific receptors in the brain and spinal cord, reducing the perception of pain. They can be effective in providing short-term pain relief for some patients, but can come with risks of tolerance, dependence, and addiction, so they are typically reserved for cases where other treatments have not been effective or are not suitable.
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• Medicinal cannabis: Medicinal cannabis contains cannabinoids like CBD and THC, which interact with the body's endocannabinoid system. It may provide pain relief through its interactions with cannabinoid receptors, anti-inflammatory properties, and potential neuroprotective effects. Medicinal cannabis has gained attention as an alternative or adjunct therapy for chronic pain management, particularly when other treatments have been ineffective or come with unwanted side effects.
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• ‍Antidepressants: Certain antidepressants, particularly tricyclic antidepressants (TCAs) and serotonin-norepinephrine reuptake inhibitors (SNRIs), can be used to manage certain types of chronic pain, such as neuropathic pain. These medications may help by increasing the levels of certain neurotransmitters in the brain, which can modulate pain signals and improve pain perception.
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• ‍Anticonvulsants: Anticonvulsant medications, such as gabapentin and pregabalin, can be used to treat neuropathic pain, which results from nerve damage or malfunction. These medications work by reducing abnormal nerve firing and stabilising overactive pain pathways.
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• ‍Muscle Relaxants: Muscle relaxants, like cyclobenzaprine and baclofen, are used to relieve muscle spasms and associated pain. They work by reducing muscle contractions and promoting relaxation.
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• ‍Topical Analgesics: Topical analgesics, such as creams, gels, or patches containing substances like capsaicin or lidocaine, can be applied directly to the skin over the painful area. These medications provide localised pain relief by numbing the nerves or reducing pain signals in the affected area.

For some patients, a combination of different medications or treatments might be the best option to achieve pain relief and minimise potential side effects and risks. 

Additionally, non-pharmacological treatments, such as physical therapy, cognitive-behavioural therapy (CBT), and lifestyle modifications, can be included in the overall pain management plan.

Medicinal cannabis and chronic pain management

Medicinal cannabis may work for chronic pain management through its interactions with the body's endocannabinoid system, which regulates various physiological functions, including pain perception. The cannabis plant contains cannabinoids such as CBD and THC, responsible for its potential therapeutic effects on pain.

Medicinal cannabis has been shown to provide an effective and relatively safe chronic pain management treatment, especially when compared with traditional opioid-based therapies. Medicinal cannabis contains active components called cannabinoids, such as THC and CBD. These cannabinoids work in our body by interacting with specific receptors called endocannabinoid receptors. The two main receptors are CB1 and CB2. When THC and CBD bind to these receptors, they can provide relief from pain.

This interaction affects the release of neurotransmitters (chemical messengers in the body) and dampens the transmission of pain signals, providing pain-relieving effects. Additionally, medicinal cannabis possesses anti-inflammatory properties, further adding to its effectiveness as a treatment for chronic pain. 

Can medicinal cannabis interact with other pain medications?

Medicinal cannabis, containing cannabinoids like CBD (cannabidiol) and THC (tetrahydrocannabinol), has the potential to interact with other pain medications commonly used alongside chronic pain management. These interactions can affect the way medications are metabolised and how they work in the body. Here's an overview of how medicinal cannabis may potentially interact with some of these medications:

• Nonsteroidal Anti-Inflammatory Drugs (NSAIDs): Medicinal cannabis and NSAIDs are considered safe to take together. Cannabis, particularly CBD, may have complementary anti-inflammatory effects with NSAIDs. This means that combining the two may enhance the overall anti-inflammatory response.

However, one recent study suggests that cannabinoids could interfere with the metabolism of NSAIDs in the body potentially leading to altered levels of the NSAIDs in the bloodstream, affecting their effectiveness. However, more research is needed to confirm this.

• Paracetamol: There are no significant interactions between medicinal cannabis and paracetamol (acetaminophen) and it’s generally safer to combine the two. However, it’s important to be wary of using CBD alongside high or prolonged doses of paracetamol as that could have a negative effect on the liver.
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• Opioids: Combining medicinal cannabis with opioids can have complex interactions. Some studies suggest that CBD may enhance the pain-relieving effects of opioids, allowing for lower opioid doses. However, this combination can also increase the risk of central nervous system depression and respiratory depression, which can be very dangerous, especially in higher doses. Careful monitoring and dosage adjustments by a healthcare provider are essential if using both treatments together.
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• ‍Antidepressants: The interactions between CBD and antidepressant medications can be complex and may result in either potentiation or an increased risk of side effects. CBD can interact with antidepressant medications, specifically those that are metabolised by the hepatic enzyme CYP2D6.

When CBD inhibits this enzyme, it can cause the levels of certain antidepressants, such as selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants, antipsychotics, beta-blockers, and opioids, to increase in the bloodstream. This could potentially lead to stronger effects or an increased risk of side effects from these medications in some patients.

While this doesn’t mean that patients can’t incorporate both antidepressants and medicinal cannabis into their treatment plan, it is important to discuss the potential interactions of these two treatments to ensure the safe and effective use of both medications. 

• Anticonvulsants: The interactions between medicinal cannabis (specifically CBD) and anticonvulsant medications can be quite complex. CBD can affect how anticonvulsants are metabolised in the body and may also influence their effectiveness. If your patient has been prescribed CBD alongside anticonvulsants, it is important to monitor them closely to ensure the effectiveness of the treatment and to minimise any potential adverse effects.
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• ‍Muscle relaxants: Medicinal cannabis may enhance the effects of muscle relaxants, leading to increased sedation and motor impairment. Combining muscle relaxants and medicinal cannabis can be dangerous and requires close and careful monitoring from a healthcare provider. If a patient in your care is combining these kinds of medications, it is important that they are aware of the risks that are involved.
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• ‍Topical analgesics: There are no significant interactions between medicinal cannabis and topical analgesics, as these are applied externally and have limited systemic absorption.
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• ‍Anti-anxiety medications: Medicinal cannabis, particularly THC, may not be safe to combine with some anti-anxiety medications (e.g., benzodiazepines). It can heighten sedative effects when combined with anti-anxiety medications and lead to excessive drowsiness and impaired cognitive function. Interestingly, medicinal cannabis may help some patients stop taking benzodiazepines. One study even shows that almost 50% of patients were able to discontinue their pre-existing benzodiazepine therapy after a two-month course of medicinal cannabis.
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• ‍Sleep aids: Combining medicinal cannabis with sleep medications (like benzodiazepines or Ambien) can be problematic. It can lead to increased drowsiness and sedation. Some people may also experience impaired judgement, thinking, and motor coordination. Dosage adjustments may be necessary to avoid excessive sedation.

It's important to remember that the above list is not exhaustive and individual responses to these combinations of medications can vary. Whenever considering prescribing a patient medicinal cannabis, it’s important to first establish if they are taking any existing medications that may interact negatively with it. This enables you to make an informed decision as a healthcare provider and ensures a safe and effective pain management plan for your patient.  

The bottom line

Chronic pain is a complex condition that affects many people. Managing it can be challenging due to balancing multiple medications, understanding your patients’ unique responses, and weighing potential risks. Medicinal cannabis, with its interactions with the body's endocannabinoid system, has shown promise as an alternative therapy for chronic pain. However, its interactions with other medications require careful consideration. 

Establishing open communication with your patients and gaining an understanding of what medications they have been previously prescribed as part of their pain management plan ensures that they receive safe and effective treatment.

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