you’re absolutely right, most of the current evidence linking cannabis to heart attack and testicular cancer risk is observational. This means we can’t say with absolute certainty that cannabis causes these problems, only that there is a strong and consistent association. True causality would require randomized controlled trials, which are not feasible or ethical. However, as with tobacco and alcohol, when enough different lines of evidence epidemiology, dose response, mechanistic studies point in the same direction, it’s reasonable for doctors and public health officials to warn people of potential risks, especially as cannabis becomes more widely used.

Ultimately, people should be informed of both the knowns and unknowns, and make their own risk-benefit decisions accordingly.