Harvard studies published in the NEJM the impact of two placebo treatments vs standard medical treatments for asthma patients. When it came to patient reported benefits, placebos were equally as effective as sthe standard treatment. However, the measured benefits of placebo on pulmonary function testing was only about 35% as effective as standart medical treatments.
A second study measured the placebo effect vs echinacea vs no treatment showed that both echinacea and placebo made people feel better faster. They concluded that what people believe about their medicines is what matters!