Take a low-dose aspirin every day to prevent heart attacks

What actually happened

The advice came from trials in the 1980s, notably the Physicians' Health Study, which showed a real reduction in first heart attacks. It became so routine that people started it without asking anyone.

Three large trials published in 2018 broke it. ASPREE, in over 19,000 older adults, found no cardiovascular benefit and a significant increase in major hemorrhage, along with a puzzling increase in all-cause mortality. ARRIVE and ASCEND pointed the same direction: modest cardiovascular benefit roughly cancelled out by bleeding, including gastrointestinal and intracranial bleeds. Part of the reason is that the background changed since the 1980s. Statins, blood-pressure control, and falling smoking rates lowered baseline risk, so the same small absolute benefit no longer clears the same harm.

The critical distinction, and this is the one that gets people hurt: this is about primary prevention, meaning people who have never had a cardiovascular event. If you have already had a heart attack or stroke or have a stent, aspirin is still standard secondary prevention and stopping it on your own is dangerous. Nobody should change an aspirin regimen based on a website. The point here is only that the blanket "everyone over 50 should take one" that was taught as common sense is no longer the recommendation.