How to Use Medical Cannabis Safely for Chronic Pain

October 3, 2025

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Clark Harrison

Chronic pain remains one of the most challenging medical conditions to treat effectively, pushing many UK residents to explore alternative therapies such as medical cannabis. With misgivings about current treatments and curiosity about how medical cannabis may offer relief, understanding its risks, benefits, and practical applications is critical. Dr Leslie Mendoza Temple, a family medicine and integrative medicine expert who has worked extensively with medical cannabis, provides a comprehensive overview of how this powerful but complex plant can be safely used for pain and related conditions.

This article distils her key teachings, tailoring them to a UK audience eager to make informed decisions about medical cannabis.

Understanding Medical Cannabis: THC, CBD, and Beyond

Cannabis is an extraordinarily complex plant, containing over 120 cannabinoids alongside terpenes that contribute to its aroma and biological effects. Two of the most well-known cannabinoids are tetrahydrocannabinol (THC) and cannabidiol (CBD):

THC is the psychoactive component responsible for the "high" sensation. It has notable pain-relieving properties but must be used cautiously due to its intoxicating effects.
CBD is non-intoxicating and is valued for its anti-inflammatory and calming properties. It can temper the effects of THC, creating a more balanced experience.

Beyond these, emerging research highlights other cannabinoids like CBG, CBC, and THCV, though their precise therapeutic roles are still under investigation.

Regulatory Clarifications for UK Residents

UK regulations distinguish between hemp (low THC, under 0.2%) and medical cannabis (higher THC content). Medical cannabis is only available via prescription, typically for conditions such as chronic pain, severe epilepsy, or chemotherapy-induced nausea.

Pain Management: What the Research Says

The strongest evidence for cannabis use lies in its effectiveness in managing chronic pain. A 2017 report from the National Academy of Sciences identified conclusive evidence supporting cannabinoids for:

Chronic pain
Chemotherapy-induced nausea and vomiting
Spasticity in multiple sclerosis

For chronic pain specifically, cannabis offers an alternative to opioids at a time when dependency and overdose risks are critical concerns. Recent studies, including a 2024 review of trials for fibromyalgia and neuropathic pain, further affirm its potential. These studies noted significant pain relief, particularly with sublingual THC oil and CBD creams applied multiple times a day.

How Does Cannabis Reduce Pain?

Cannabis interacts with the body’s endocannabinoid system, particularly CB1 receptors in the brain. Research shows that it can downregulate activity in areas like the anterior cingulate cortex, helping to modulate pain perception. Patients often describe feeling more relaxed, with pain becoming less overwhelming.

Starting Medical Cannabis: A Step-by-Step Guide

For those new to cannabis, the golden rule is "start low and go slow." Here’s a practical roadmap:

1. Choosing the Right Product

Edibles: Best for long-lasting effects, including overnight pain relief or insomnia. Onset may take 1–2 hours.
Tinctures: Faster onset (15–30 minutes) when taken sublingually and allow precise dose control.
Topicals: Ideal for localised pain with no psychoactive effects. Can supplement other forms of cannabis.
Smoking and Vaping: Quick relief but not recommended due to risks of respiratory damage and cardiovascular concerns.

2. Dosing Recommendations

Start with ultra-low doses: 1.25–2.5mg THC combined with any CBD content.
Gradually increase the dose based on tolerance and symptom relief, with increments of 1mg THC if needed.
Avoid high-THC products initially to minimise risks of anxiety or intoxication.

3. Practical Tips

Use cannabis at bedtime to mitigate intoxicating effects.
Separate cannabis from other medications by 1–2 hours to reduce interaction risks.
Maintain a symptom diary to track effects and fine-tune dosing.

Safety Considerations and Side Effects

While generally safer than opioids, medical cannabis is not risk-free. Dr Mendoza Temple emphasises the need for vigilance in addressing potential side effects:

Common Side Effects:

Dizziness, sedation, and dry mouth
Gastrointestinal upset
Potential for intoxication, especially with high-THC products

Rare but Serious Complications:

Cannabis Hyperemesis Syndrome (CHS): Characterised by nausea and vomiting after prolonged use. Hot showers often provide temporary relief.
Cannabis Use Disorder: Overuse can lead to dependency in about 9% of users, with symptoms like impaired judgement, withdrawal, and continued use despite harm.

Drug Interactions:

Cannabis metabolism involves liver enzymes (CYP450), which can interact with medications like blood thinners, antidepressants, and antibiotics. For example:

Warfarin (Coumadin): CBD can increase bleeding risks.
Fluoxetine (Prozac): May amplify THC’s psychoactive effects.

Patients with complex medication regimens must consult their healthcare provider before starting cannabis.

Addressing Stigma and Navigating Practical Barriers

One of the biggest hurdles for UK patients is overcoming the stigma associated with cannabis use. Many remain hesitant due to its historical association with recreational drug use. However, as medical cannabis becomes more mainstream, the focus is shifting toward its therapeutic potential.

Affordability Challenges

In the UK, medical cannabis is not currently covered by the NHS, leaving patients reliant on private prescriptions. Additionally, high-quality products such as patches and tinctures can be prohibitively expensive. Patients may consider making their own cannabis oils or creams to offset costs.

Driving and Legal Implications

It is illegal to drive under the influence of cannabis in the UK. Patients should avoid driving until they are confident in how cannabis affects them and always adhere to prescribed doses.

Opportunities for Healthcare Professionals

Dr Mendoza Temple encourages UK healthcare providers to become more informed about medical cannabis. By joining advisory boards or policy committees, clinicians can influence the development of cannabis regulations and advocate for patient-centred care.

Key Takeaways

Start Low, Go Slow: Begin with 1.25–2.5mg THC and gradually adjust as needed.
Choose the Right Form: Tailor cannabis delivery (e.g., edibles, tinctures, topicals) to your needs.
Track Symptoms: Maintain a diary to monitor effects and optimise dosing.
Prioritise Patient Safety: Be mindful of drug interactions and side effects like CHS.
Combat Stigma: View medical cannabis as a legitimate therapeutic option, not a last resort.
Explore Alternatives: For cost-conscious patients, consider DIY cannabis creams or oils.
Educate and Empower: Clinicians should actively seek training and certification to guide patients effectively.

Conclusion

Medical cannabis represents a promising yet complex option for managing chronic pain and associated conditions. It offers hope to those struggling with inadequate relief from conventional treatments but requires careful application to maximise benefits and minimise risks. By emphasising personalised care, patient education, and a cautious approach, medical cannabis can become a powerful tool in improving quality of life for chronic pain sufferers.

As the field continues to evolve, ongoing research and policy development will be essential in unlocking the full therapeutic potential of this ancient yet modern remedy. Whether you’re a patient or a healthcare provider, staying informed and open-minded is the key to navigating this transformative landscape.

Source: "(Freemedbooks.com) Medical Cannabis – Time for Reassessment" – Anesthesia, Critical Care And Pain Medicine, YouTube, Jan 1, 1970 – https://www.youtube.com/watch?v=cFqfFLQAKeg

Use: Embedded for reference. Brief quotes used for commentary/review.