Hippocrates urged us, first, do no harm, but this should not be overinterpreted to accept no risks in making treatment decisions. Such a stance would leave us paralyzed as physicians because nearly every medical therapy and surgical intervention has a risk of complications. It is the calculus of the risk-benefit ratio that must be considered in making treatment decisions, and there has been a common misunderstanding of the math relevant to using tPA for stroke.
Bambauer KZ, Johnston SC, Bambauer DE, Zivin JA. Nonstroke Treatment—Reply. Arch Neurol. 2006;63(10):1506-1507. doi:10.1001/archneur.63.10.1506-b