The cannabis plant has been used as a medicinal agent for centuries. Cannabis produces hundreds of compounds, including tetrahydrocannabinol (THC). THC, the psychoactive substance in cannabis, has been demonised by society for generations. However, used appropriately, it can be an excellent treatment for some medical conditions.
Today on the Cannactiva blog, we review the beneficial properties THC has shown according to the latest scientific research. Note: this is an informational article and is not intended to prevent, diagnose or treat any disease.
History of medical cannabis
The medicinal use of cannabis goes back thousands of years, to its cultivation in China around 4000 BC, where it was used to treat various ailments. From there, it spread to India, the Middle East, Africa and Europe. However, the medicinal use of cannabis declined in the 20th century due to prohibitionist policies, legal restrictions and the variability of its effects.
However, the discovery of the endocannabinoid system in the 1990s renewed scientific interest in the cannabis plant. Today, medical cannabis is legal in many regions, backed by growing scientific evidence.
THC and CBD (cannabidiol): two distinct cannabinoids
Tetrahydrocannabinol (THC) and cannabidiol (CBD) are the two most studied cannabinoids in the cannabis plant. The main difference is that THC is the psychoactive substance, whereas CBD is non-psychoactive and is used in legal products in the European Union with a THC content of no more than 0.3%.
At Cannactiva we work exclusively with CBD products intended for external use, within the European legal framework. This article is for information only and focuses on the available scientific research on THC; it is not a recommendation for use and does not refer to products sold by Cannactiva. If you're interested in cannabidiol, you can read our guide on what CBD is and what it's for.
Recommended reading: History of the medicinal uses of cannabis
Areas of scientific research on THC
THC and chronic pain: research findings
The use of cannabis to relieve chronic pain is the main reason mentioned by patients seeking medical treatment with this plant.
Studies have shown that a large majority of patients with medical cannabis cards use it to treat severe pain (5), and there are signs that many are substituting cannabis for opioids, significantly reducing their use of these conventional painkillers (6).
Although clinical trials suggest that plant cannabinoids can relieve pain (7, 8), research on the efficacy, dosage, methods of administration, and side effects of commercially available cannabis products remains insufficient.
Recommended reading: CBD dosage for pain
THC and sleep disorders in scientific studies
THC may help in the treatment of short-term sleep disorders, especially in people with insomnia and other sleep-related disorders secondary to other medical conditions, such as pain (20).
By binding to cannabinoid receptors in the brain, THC can influence the release of neurotransmitters that promote sleepiness and reduce wakefulness, thus facilitating better sleep when used for short periods of time, as it could affect sleep quality in the long term (20).
THC as an antiemetic: studies in chemotherapy
Drugs used in chemotherapy often cause nausea and vomiting as side effects. To treat these symptoms, several types of drugs, including the cannabinoids nabilone and dronabinol, have been approved since 1985 (1).
These oral drugs have been shown to be effective in controlling chemotherapy-induced nausea and vomiting, comparable to traditional treatments and superior to placebo (2, 3), which has also been shown for THC used together with CBD (4). Furthermore, the effects of cannabidiol (CBD) have not been studied in this context, which is a need expressed by patients who wish to avoid the psychoactive effects of THC. Research in this area could be important in the future.
Recommended reading: CBD to reduce the effect of THC
THC and appetite stimulation: scientific review
THC may increase food intake to prevent weight loss observed in some diseases, such as cancer or HIV/AIDS (9-12).
Small studies have indicated that cannabis increases appetite and calorie intake, mainly through increased snacking (13). While this may be due to the synergistic effect of many of the components of the cannabis plant and not necessarily THC by itself, it is still a good option as palliative care in cancer.
THC and spasticity in multiple sclerosis: available evidence
Spasticity, caused by damage to upper motor neurons, manifests as involuntary muscle contractions and affects people with chronic neurological diseases such as multiple sclerosis (MS) and paraplegia due to spinal cord injury (14). Some MS patients use cannabis to relieve symptoms, and studies suggest that certain oral THC extracts may slightly reduce spasticity as perceived by patients, although they have not consistently demonstrated improvements in medical evaluations (8, 15).
Recommended reading: Cannabis and CBD for multiple sclerosis: studies
THC and Tourette syndrome: preliminary studies
Tourette syndrome is a neurological condition that causes involuntary movements or sounds called “tics”. Although there is no cure, studies with THC have shown an improvement in the severity of tics (8, 16, 17).
No clear link between the syndrome and the mechanisms of cannabis has been demonstrated, although some reports suggest that it may reduce tics due to its anxiety-reducing effects.
THC and Parkinson's disease: current research
Medical cannabis has shown improvement in tremors resulting from parkinsonism as reported by two research groups (17, 19). However, it does not appear to be helpful with involuntary movements induced by levodopa (17), which is the primary treatment for Parkinson's disease.
Recommended reading: CBD for Parkinson's disease
THC and glaucoma: findings and scientific limitations
Glaucoma is a major cause of blindness and is characterised by damage to the optic nerve due to raised eye pressure. Treatments focus on reducing this pressure.
Some studies suggest that cannabis may lower eye pressure, but only temporarily (18). An appropriate treatment for reducing intraocular pressure should offer sustained effects; given that THC produces tolerance at some point and dose escalation means more psychoactive effects for patients, it is not considered the best alternative.
Conclusions from scientific research
THC has significant therapeutic potential, particularly for managing the symptoms of chronic diseases and certain health conditions. However, its use should be managed by a healthcare professional to minimise risks, especially considering individual variations in response to cannabis-based treatments. Although research into cannabis for medicinal use is still ongoing, two major drawbacks of its use are the development of tolerance and the psychoactive effect.
Note: this is an informational article and is not intended to prevent, diagnose or treat any disease. Its content can complement, but should never replace, the diagnosis or treatment of any disease or symptom. Cannactiva products are not medicines and are intended for external use. There may be relevant new scientific evidence since the date of publication. Consult your doctor before using CBD. The therapeutic approach must always be personalised and will depend on professional assessment.
References
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- Phillips, R. S., Friend, A. J., Gibson, F., Houghton, E., Gopaul, S., Craig, J. V., & Pizer, B. (2016). Antiemetic medication for prevention and treatment of chemotherapy-induced nausea and vomiting in childhood. The Cochrane database of systematic reviews, 2(2), CD007786. https://doi.org/10.1002/14651858.CD007786.pub3
- Smith, L. A., Azariah, F., Lavender, V. T., Stoner, N. S., & Bettiol, S. (2015). Cannabinoids for nausea and vomiting in adults with cancer receiving chemotherapy. The Cochrane database of systematic reviews, 2015(11), CD009464. https://doi.org/10.1002/14651858.CD009464.pub2
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