Definition: A placebo is an inactive substance or other treatment that looks the same as, and is given the same way as, the drug being tested. The NCI says the effects of the drug are compared with the effects of the placebo. Labels often show side-effect rates on placebo next to the rates on the drug.
In a placebo-controlled study, 21 CFR 314.126 says the drug is compared with an inactive preparation made to resemble it as far as possible, usually with randomization and blinding. When giving a placebo would go against a patient's interest, the rule allows a known effective drug as the comparison instead; see noninferiority trial.
| Label | On the drug | On placebo |
|---|---|---|
| Ozempic (type 2 diabetes) | 15.8% (0.5 mg), 20.3% (1 mg) | 6.1% |
| Mounjaro (type 2 diabetes) | 12% to 18% | 4% |
| Zepbound (weight trials) | 25% to 29% | 8% |
| Wegovy 2.4 mg injection (weight trials) | 44% | 16% |
People on placebo report side effects too. The gap between the two columns, not the drug column alone, is the part these trials tie to the drug.
A log that starts before the first dose shows which symptoms, such as headaches or an upset stomach, were already there. That makes it easier to tell what changed after starting.
Read more on Dose Track: Ozempic side effects · Mounjaro side effects · Zepbound side effects · Wegovy side effects