Tetrahydrocannabinol or THC is the most abundant cannabinoid in most cannabis varieties and has the most potent psychoactive effect. It was Dr. Raphael Mechoulam who first discovered THC in 1964 and has since investigated its’ therapeutic potential. Currently, in international medical research portals, there are more than 8000 articles that analyze the use of tetrahydrocannabinol from a therapeutic approach. THC is a partial agonist of the cannabinoid receptors CB1 and CB2 (it has a more potent effect on CB1) exerting analgesic, anti-inflammatory, antiemetic, orexigenic, anti-tumour, antiepileptic, anti-spastic and spasmolytic effects. Current studies have shown that in addition to its effect on CB1 and CB2 THC also acts on other receptors such as GPR55 or TRPV1-5, influencing this way on nociception, thermoregulation, salivary secretion, smooth muscle tone, heart rate and on the homeostasis of calcium and magnesium (Ligresti et al., 2016).
The side effects of THC have been described as anxiety, psychoactive effects, depression, cholinergic deficit, loss of immediate memory, impairment of concentration capacity, an affectation of balance and coordination of movements, conjunctival hyperaemia (red eyes), mucosal dryness (dry mouth) and increased appetite and sleep.
Therapeutic Effects of Tetrahydrocannabinol (THC)
THC or delta-9-tetrahydrocannabinol (Δ9-THC) has analgesic and anti-spasmodic effects and has the ability to relax all of the senses. It is also known to be an antagonist of several cannabinoids, such as CBD, which reduces the psychoactive effects of THC.
The main therapeutic effects of THC are as follows:
There are currently numerous studies focused on the treatment of cancer using THC (and other cannabinoids), which have demonstrated anti-tumour effects in animal testing. Human trials are currently being conducted at universities in Israel and the United Kingdom. Until there are more references of trials where it is analyzed in humans, oncologic patients can use cannabinoid treatment as an adjuvant to the usual treatments, THC is able to palliate the typical adverse side effects of chemotherapy, such as nausea, vomiting, sleep deficit or lack of appetite.
There have also been several studies on the therapeutic potential of THC in Alzheimer, which investigate the potential neuroprotective effects for this type of pathology. They have also looked at its potential in states of dementia and as a treatment for periods of agitation and aggression.
Among the most widely known therapeutic applications for THC is the treatment of multiple sclerosis and severe spasticity. It is normally administered via a mouth spray made of a THC | CBD ratio of 1:1, it is predominantly for patients who have not seen results with other types of anti-spastic treatments.
THC at the moment
One of the crucial elements of THC is that because it is a psychoactive element, it is considered an illegal substance in several countries. The legal limit of THC in products with cannabinoids is 0.2%, in order to be marketed to the world.
Thanks to the findings of medical trials and the openness towards research, access to the various cannabinoids is being allowed, among which is tetrahydrocannabinol. In addition, there are currently accepted medicines, like Sativex, that have demonstrated its therapeutic usefulness via clinical trials.
Bibliography for THC – Tetrahydrocannabinol
 Ligresti A, De Petrocellis L, Di Marzo V. From Phytocannabinoids to Cannabinoid Receptors and Endocannabinoids: Pleiotropic Physiological and Pathological Roles Through Complex Phar- macology. Physiol Rev. 2016;96(4):1593-659
 Liu CS, Chau SA, Ruthirakuhan M, Lanctôt KL, Herrmann N. Cannabinoids for the Treatment of Agitation and Aggression in Alzheimer’s Disease. CNS Drugs. 2015 Aug;29(8):615-23. doi: 10.1007/s40263-015-0270-y