The continual and uninterrupted expansion of medical research funding is generally assumed to be a permanent feature of modern societies, but this expectation may turn out to be mistaken. Sciences tend to go through boom and bust phases. Twentieth century physics is an example where huge increases in funding followed an era of scientific breakthroughs. Speculative over-expansion led to diminishing returns on investment, then a collapse in funding. We predict that medicine will follow the same trajectory. After prolonged over-funding of the 'basic-to-applied' model of clinical innovation, and a progressive shift towards Big Science organization, medical research has become increasingly inefficient and ineffective. Although incremental improvements to existing treatment strategies continue, the rate of significant therapeutic breakthroughs has been declining for three decades. Medical science now requires rationalization and modernization. From this perspective, the current level of medical research funding looks like a bubble due to burst.