EducationThe Medical Benefits of THC explained

The Medical Benefits of THC explained

13 min read

Sam North

The Medical Benefits of THC explained


THC, or tetrahydrocannabinol, is the most prominent cannabinoid in most cannabis sativa L. strains, and the compound that produces the psychoactive, intoxicating effects associated with cannabis. But, along with the recreational effects of THC, the growing body of medical research on THC suggests it can provide therapeutic and medicinal benefits for a variety of health conditions.

Cannabis containing THC is thought to be one of the first plants ever grown in an agricultural setting, and it has been administered for medicinal purposes in cultures around the world for thousands of years.

Cannabis has a rich history in medical literature, with the earliest mention dating back to around 2800 BC. Emperor Shen Nung, revered as the father of Chinese medicine, included cannabis in his pharmacopoeia. Throughout history, various cultures such as the Indian Hindus, Assyrians, Greeks, and Romans recognized the therapeutic potential of cannabis. These ancient texts documented its efficacy in treating a wide range of health issues, including arthritis, depression, amenorrhoea (the absence of menstrual periods), inflammation, pain, appetite issues, and asthma. The enduring legacy of cannabis as a medicinal remedy is a testament to its diverse healing properties.

In this article, we are going to go on a deep dive into the currently available scientific research regarding the potential benefits of THC, and see if we can lay out the facts in simple, easy-to-digest language.

How does THC work?

THC works by interacting with and activating the body’s endocannabinoid system (ECS).

The ECS is the largest neurotransmitter system in the body, and is made up of receptors (CB1 and CB2) located throughout the body, in the brain, connective tissue, immune cells, organs and glands. These receptors are activated by our endocannabinoids, which act as the chemical messengers responsible for switching on and off the various physiological functions throughout the body. This extensive network plays a role in many physiological processes that control things like memory, appetite, pain sensation, sleep cycles, mood, and immune functions.

THC is classed as a cannabinoid (or actually a phytocannabinoid, to be more precise), just like our endocannabinoids. This is due to the fact that phytocannabinoids have a remarkably similar chemical structure to our endocannabinoids, allowing them to interact with the ECS receptors, and modulating the physiological processes they control.

THC and one of our endocannabinoids, anandamide, exhibit a remarkably analogous chemical make-up. Anandamide binds to the CB1 receptors, as does THC. CB1 receptors are located in the brain and nervous system (which is why THC produces a psychoactive effect), but they are also found in other parts of the body. THC has also been shown to interact with the CB2 (albeit, in a weaker fashion) and other receptors, making it much more than just a recreational psychotropic.

This means that THC has the potential to have a modulatory effect on a wide variety of physiological processes, but is most often prescribed for pain relief, chronic inflammation control, neurological disorders, mental health issues, and the reduction of side effects related to cancer treatments.

One thing that is imperative to point out is that medical cannabis as a whole should never be seen as a miracle cure-all, or even a replacement for conventional medicine. However, numerous peer-reviewed studies are showing that, when administered correctly, THC can be an effective complementary form of treatment for a wide range of medical conditions, and their related symptoms.

THC and pain relief

There are three main forms that pain can take – acute, chronic, and neuropathic.

  • Acute pain is the most common form of pain. It encompasses various types of injuries, such as sprains, strains, or post-operative issues, that typically last for a few days or weeks before gradually subsiding. During this period, the body undergoes a natural healing process where inflammation and discomfort are present.
  • Chronic pain is a persistent and enduring type of pain that lasts for months, and in some cases, even years. It is frequently linked to chronic health conditions like arthritis, fibromyalgia, or chronic back pain. Individuals experiencing chronic pain often endure ongoing discomfort and struggle with managing their daily activities due to the long-lasting nature of their pain.
  • Neuropathic pain (or nerve pain) occurs when the nervous system becomes damaged or irritated, which can be caused by various factors such as injuries, infections, or certain medical conditions. This type of pain is characterized by shooting sensations, numbness, and tingling, often accompanied by a burning or electric shock-like feeling. It can be chronic and persistent, affecting the quality of life for individuals who experience it. Understanding the underlying causes and seeking appropriate medical treatment are crucial steps in managing and finding relief from neuropathic pain.

So, how does THC fit into all of this?

Recent research has indicated that, when administered in proper doses, THC can provide effective pain management for all three types of pain – acute, chronic, and neuropathic. THC has been shown to be particularly effective in treating more severe forms of pain, such as neuropathic and chronic pain, but that's not to say it is useless for more acute pain. It has been established that THC can help to reduce the inflammation and discomfort associated with acute pain, while enabling patients to maintain regular daily activities.

One systematic review, which looked at four studies focusing on the efficacy of cannabis to treat surgical and non-surgical back pain, found that

“In all articles, cannabis was shown to be effective to treat back pain with an acceptable side effect profile”

Another study supported this, suggesting that THC's intoxicating effects may contribute to the perceived pain reduction. When researchers induced pain in healthy participants and treated them with THC, they observed decreased activity between the amygdala and primary sensorimotor areas. Although participants still acknowledged the pain, it bothered them less compared to those who received a placebo.

THC administration for chronic pain has demonstrated the ability to decrease the need for opioid medications (by up to 64% in one study), thereby mitigating the potential for detrimental and potentially fatal side effects. Given the prevailing opioid epidemic, the significance of medicinal cannabis as a viable treatment option has grown exponentially.

When it comes to more chronic pain issues, THC has again been found to be an effective treatment option, with some caveats. One systematic review of twenty-five individual studies was conducted to assess the advantages and potential drawbacks of cannabinoids in the treatment of chronic pain. It found that

“Cannabis products with high THC-to-CBD ratios and sublingual, extracted cannabis products with comparable THC-to-CBD ratios may be associated with short-term improvements in chronic pain”

This essentially means that THC (when combined with CBD) may be an effective treatment for chronic pain when administered in the right doses and through the appropriate delivery mechanism. But, as with most other research papers looking at the efficacy of THC in treating chronic pain, the authors concluded that further research is needed to get a better understanding of its potential.

When it comes to neuropathic pain, the literature has demonstrated clearer results, and these results are certainly promising. A 2010 randomized controlled trial, titled “Smoked cannabis for chronic neuropathic pain”, found that

“A single inhalation of 25 mg of 9.4% tetrahydrocannabinol herbal cannabis three times daily for five days reduced the intensity of pain, improved sleep and was well tolerated.”

Another paper we can look at is “Cannabis‐based medicines for chronic neuropathic pain in adults”. This comprehensive review, consisting of sixteen studies and involving a total of 1750 participants, aimed to evaluate the effectiveness, tolerability, and safety of cannabis-based medicines (including herbal, plant-derived, and synthetic) in comparison to placebo or conventional drugs for the treatment of chronic neuropathic pain in adults. It demonstrated that current pharmacological treatment options for neuropathic pain have limited effectiveness and often come with adverse effects that outweigh the benefits, and that

“Cannabis‐based medicines may increase the number of people achieving 50% or greater pain relief compared with placebo”

THC and anxiety reduction

Anxiety is a multifaceted and wide-ranging mental health condition. From generalized anxiety disorder (GAD) and social anxiety disorder (SAD) to panic attacks and PTSD, the symptoms of this mental health condition vary significantly from one sufferer to the next.

Current statistics point to up to 60% of the UK population “experiencing at least mild symptoms of anxiety”, with over eight million people experiencing an anxiety disorder at any one time.

THC application for anxiety issues is, at least somewhat, controversial due to the inebriating effects of the chemical. While this is a valid concern (high doses of THC have been known to produce short-term anxiety, panic, and paranoia for some patients), there is also evidence to suggest that it can be beneficial when administered in the right dosage size.

Anxiety and cannabis: a review of recent research”, an article published in April 2023, found that THC appears to decrease anxiety at lower doses and increase anxiety at higher doses. This finding is backed up by a paper published by the Alcohol and Drug Abuse Institute, which found that the

“effects of cannabis on anxiety disorders are complex. The endocannabinoid system appears to play an important role in responses to stress and anxiety. The two primary active ingredients of marijuana, THC and CBD, appear to have differing effects with regard to anxiety. Pure THC appears to decrease anxiety at lower doses and increase anxiety at higher doses”

THC eases nausea and reduces vomiting

One of the very first medical applications of cannabis was for the treatment of nausea and vomiting, specifically for cancer patients receiving chemotherapy. In 1986, the US Food and Drug Administration (FDA) approved a synthetic form of THC for the treatment of chemotherapy-induced nausea and vomiting.

Since then, extensive research has been conducted to explore the efficacy of this treatment in reducing feelings of nausea, which can potentially lead to vomiting. The results of these studies have been encouraging.

One early study, from all the way back in 1995, looked at delta-8-tetrahydrocannabinol (delta-8-THC), a cannabinoid that is very similar to regular THC lower psychotropic potency than delta-9-tetrahydrocannabinol, which is what we simply refer to as THC. It was administered in oil edible form every 6 hours for 24 hours, which resulted in vomiting being completely prevented.

The 2011 British Journal of Pharmacology paper, titled "Regulation of nausea and vomiting by cannabinoids". There are a few key takeaways here, including

  • “Manipulation of the endocannabinoid system regulates nausea and vomiting in humans and animals”
  • “CB1 agonism suppresses vomiting, while CB1 inverse agonism promotes vomiting" THC is a full agonist for the CB1 receptor
  • "Animal experiments suggest that cannabinoids may be useful in treating difficult-to-control symptoms of nausea and anticipatory nausea in chemotherapy patients"

THC and neurological disorders

Another area where THC may prove to be beneficial is in the management of neurological disorders, such as Parkinson’s disease, Huntington’s disease, and Alzheimer’s.

For Parkinson’s disease, we have the 2019 paper "Pros and Cons of Marijuana in Treatment of Parkinson’s Disease" which concluded

"Self-medication with marijuana has improved many symptoms including bradykinesia, tremor, rigidity, depression, sleep, and pain", but also noted that "more research is required to study the effects of marijuana in patients with PD, for which treatment is limited"

We can also look at "Cannabis in Parkinson’s Disease: The Patients’ View", published in the Journal of Parkinson's disease. The authors state that

"reduction of pain and muscle cramps was reported by more than 40% of cannabis users. Stiffness/akinesia, freezing, tremor, depression, anxiety and restless leg's syndrome subjectively improved for more than 20% and overall tolerability was good. Improvement of symptoms was reported by 54% of users applying oral CBD and 68% inhaling THC-containing cannabis. Compared to CBD intake, inhalation of THC was more frequently reported to reduce akinesia and stiffness"

When it comes to Huntington’s disease, this 2018 published paper found that

"Improvement of motor symptoms, mainly dystonia, led to several relevant improvements from a global clinical perspective such as improvement of care, gait and fine motor skills and weight gain. Moreover, we observed changes in behaviour with less irritability and apathy, as well as less hypersalivation in some cases."

And for Alzheimer’s, there is this clinical review which included 9 studies. This wide-ranging review found that

"CBD components of cannabis might be useful to treat and prevent AD because CBD components could suppress the main causal factors of AD. Moreover, it was suggested that using CBD and THC together could be more useful than using CBD or THC alone."

The wrap up

So, there we have it. A brief overview of some of the potential medical benefits of THC. As the research suggests, THC application isolated from other cannabinoids (and terpenes) may offer numerous therapeutic benefits for a wide range of medical conditions, but it may be better administered in combination with other compounds for more effective treatment.

This points towards the "entourage effect”, where the administration of multiple cannabinoids and terpenes may work synergistically for greater therapeutic effects.

But, as with anything related to medical cannabis, the importance of finding the right dosage size and ratio of compounds cannot be overstated. This is why it is essential to seek the help of a medical professional before engaging in any form of cannabis therapy.

Releaf understands that finding a doctor who is registered to prescribe medical cannabis in the UK can be challenging. That's why we offer online consultations with our specialist doctors, as well as a unique medical cannabis card for extra protection while accessing to the treatment you need. If you're interested in learning more about our services or getting access to medical cannabis treatment options, get in touch and one of our team members will be happy to help.

It is important to seek medical advice before starting any new treatments. The patient advisors at Releaf are available to provide expert advice and support. Alternatively, click here to book a consultation with one of our specialist doctors.

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Sam North, a seasoned writer with over five years' experience and expertise in medicinal cannabis, brings clarity to complex concepts, focusing on education and informed use.

Our articles are written by experts and reviewed by medical professionals or compliance specialists. Adhering to stringent sourcing guidelines, we reference peer-reviewed studies and scholarly research. View our editorial policy.

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