Having an effect is different from being able to sell a product based on that effect. For regulated fields like pharmacy, the FDA regulatory approval test requires proving efficacy against a placebo. A doctor may (under certain specific circumstances) treat a patient using a placebo (because medicine's aim is to do whatever that is necessary to alleviate the problem or reduce suffering, it is different from pure biological natural sciences/pharmacy where inferences must be backed up by scientific theory and validated by empirical evidence) but it does not necessarily mean that a placebo can be sold/marketed as a cure.