I didn't say that, I said it's a trade-off. Taking them reduces pain and the risk of certain complications, but increases the risk of other complications (side effects). According to https://www.consumerreports.org/prescription-drugs/too-many-..., "The amount of harm stemming from inappropriate prescription medication is staggering. Almost 1.3 million people went to U.S. emergency rooms due to adverse drug effects in 2014, and about 124,000 died from those events." So even if a medicine is side effect free when used as prescribed, there are still risks if it's accidentally misused, and painkillers are not side-effect free even when used as prescribed.

Thought effect: if you had the option to eliminate a kid's pain with an 0.01% chance of causing a lasting defect, would you do it? Not everybody would; different people have different time preferences.