THC: hero or villain?

You must have heard the phrase: "the difference between poison and medicine is in the dose." Well, this same logic applies to the effects of THC.

Culturally demonized, the delta-9-tetrahydrocannabinol molecule (Δ9-THC) is one of the cannabinoids present in the Cannabis sativa plant. Prejudice surrounding it is associated with its psychoactive potential, meaning it can alter the level of consciousness and induce the famous "highs", depending on the dose.

But, to understand where all this stigma around the plant and, especially, THC came from, it is necessary to go back a bit in history.

Marijuana is one of the oldest plants on record. Its presence in the biosphere dates back to about four thousand years, and it was one of the central elements during the Age of Exploration, when its fibers were used as raw material in the production of ropes and sails for the ships used in the colonial enterprise of the 16th century.

In medicine, the plant appeared in the first pharmacopoeia on record, the Pen Tsao Ching, and as early as the 1st century, it was used as a sedative during surgeries in China - similarly to the Indians, who used it to treat pain, inflammation, and respiratory problems.

Regarding the medicinal use of Cannabis spp., historiography shows that, for much of the 18th, 19th, and 20th centuries, marijuana was commonly used as a medicine in various cultures.

It is believed that the plant was introduced in Brazil, especially in the North and Northeast regions, by enslaved people brought from Africa. Until the early 20th century, marijuana was considered a useful medicine for the treatment of various diseases.

However, since the Proclamation of the Republic, Brazilian intellectual and political elites consolidated the need to import the European biologically deterministic scientific discourse, which justified the failure of the supposed republican equality. After all, how to explain that the country adhered to egalitarian ideals if, in practice, the hierarchical structures of slavery remained?

Thus, the elites turned to science not only to justify inequalities but also to classify social groups considered undesirable, such as criminals, "vagrants," and the sick. In this context, marijuana came to be seen as an enemy of the civilizing and hygienist movement that was inaugurated in Brazil.

If, on the one hand, the biologically deterministic discourse legitimized republican inequality, on the other hand, it pointed to the problem of an uncertain future for the Brazilian nation.

Away from this moralistic and hygienist discourse, it is now known that the values of the median lethal dose (LD50) for oral administration of THC in rats range between 800 and 1900 mg/kg, depending on sex and species. Due to the low toxicity of cannabinoids, there are no records of deaths in cases of therapeutic use. This is due to the absence of cannabinoid receptors in the brainstem, the region responsible for regulating respiration and other vital functions of the body.

The prolonged use of Cannabis sativa is not associated with increased mortality in animals or humans. However, chronic marijuana use is not without risks, as it can affect the endocrine, immune, respiratory tract (when inhaled), and psychological systems.

Taking all these points into consideration, it is important to emphasize that THC, in low doses and with proper medical supervision, is indeed a substance used for therapeutic purposes and plays a vital role in the treatment of chronic pain, insomnia, nausea, chemotherapy-related vomiting, and acts as an enhancer in the so-called entourage effect.

With this in mind, THC should be recognized as an important therapeutic agent that deserves to be treated with less prejudice and more science.

References

DIAS, Luiza Lima; PEREIRA DOS SANTOS, Saulo Carneiro. Breve história da maconha no Brasil e suas relações com a moralidade na formação da República. Revista Aedos, [S. l.], v. 13, n. 28, p. 281–322, 2021. Available at: https://seer.ufrgs.br/index.php/aedos/article/view/116111. Accessed on: Sep 27, 2025.

LOPES, Márcia. Legalização da maconha: debate político, social e jurídico sobre sua pertinência. 2015.

DE PAULA SACRAMENTO, J. G. Depressão e fibromialgia, o manejo dos canabinoides e efeito entourage: relato de caso. RBCann [Internet]. Sep 18, 2025 [cited Sep 28, 2025];1(1). Available at: https://revistacannabis.med.br/sbec/article/view/123

PINHEIRO, P. X.; ROCHA, G. de O. (2024). Diferença entre o canabidiol e o delta-9-tetrahidrocanabinol no manejo da dor crônica. Revista Ibero-Americana de Humanidades, Ciências e Educação, 10(9), 2388–2395. https://doi.org/10.51891/rease.v10i9.15548