​”On the Preparations of the Indian Hemp, or Gunjah (Cannabis Indica)” by W. B. O’Shaughnessy, M.D., is a seminal 19th-century work that explores the medicinal potential of cannabis. Drawing from his experiences in colonial India, O’Shaughnessy investigates the effects of cannabis on both animals and humans, particularly its application in treating convulsive disorders like tetanus. His methodical approach combines traditional knowledge with empirical experimentation, laying the groundwork for future pharmacological studies.​

O’Shaughnessy’s experiments revealed that cannabis resin induces notable physiological responses, especially in carnivorous animals, which exhibited signs of intoxication and motor impairment. In contrast, herbivorous animals showed minimal effects, suggesting species-specific reactions. These findings underscored the importance of dosage and species considerations in therapeutic applications. Encouraged by these results, O’Shaughnessy proceeded to clinical trials on humans, particularly focusing on patients suffering from tetanus, a condition with limited treatment options at the time.​

The clinical cases documented in the work demonstrate the potential of cannabis in alleviating the severe symptoms of tetanus. Patients administered with cannabis preparations experienced significant relief from muscle spasms and convulsions, with some achieving full recovery. These outcomes highlighted cannabis’s sedative and muscle-relaxant properties, offering a promising alternative to existing treatments. O’Shaughnessy’s meticulous documentation of dosages, administration methods, and patient responses provided valuable insights for medical practitioners.​

Beyond its immediate clinical implications, O’Shaughnessy’s work emphasized the need for integrating traditional medicinal practices with scientific inquiry. By systematically studying a plant long used in various cultures, he advocated for a more inclusive approach to medicine that values empirical evidence and cultural knowledge. His pioneering research not only expanded the therapeutic repertoire of his time but also paved the way for future investigations into the medical uses of cannabis.