Post-Market Surveillance: How Drugs Are Monitored After Approval

When a drug gets approved, it doesn’t mean the story ends. Post-market surveillance, the ongoing monitoring of drugs after they’re sold to the public. Also known as pharmacovigilance, it’s how we catch problems that only show up when thousands—sometimes millions—of people are using a medicine daily. Clinical trials are tight, controlled, and short. They rarely catch side effects that show up years later, or reactions that only happen in people with other health conditions. That’s where post-market surveillance steps in.

It’s not magic. It’s made of real people reporting weird symptoms, doctors spotting odd patterns, and data systems flagging spikes in hospital visits. Think of it like a early warning system. When a drug causes rare but serious issues—like DRESS syndrome from antibiotics, or delayed angioedema from ACE inhibitors—it’s often first noticed through these reports. The FDA and Health Canada don’t wait for perfect data. They act on signals. That’s how we learned statins could mess with sleep, or that ashwagandha might push thyroid meds too far. These aren’t hypotheticals. They’re real cases pulled from the same systems that track post-market surveillance.

It’s not just about dangerous side effects. It’s about interactions, too. Warfarin and vitamin K? That’s a classic. But now we see it with supplements, OTC meds, and even foods. Post-market surveillance catches these when they slip through the cracks of pre-approval testing. It’s also how we found out pediatric cough syrups were risky under age six, or that calcium deficiency could trigger migraines in people who never thought to link the two. The system works because it’s messy, human, and real. It doesn’t rely on labs—it relies on lived experience.

You might think, "I’m not a doctor, so why does this matter to me?" Because you’re the data. Every time you notice something off after starting a new pill—trouble sleeping, strange dreams, a rash that won’t go away—you’re part of this system. Reporting it isn’t just helpful. It’s critical. The more we know, the safer future patients become. And that’s the whole point.

Below, you’ll find real stories and deep dives into the drugs and reactions that post-market surveillance has uncovered. From statins and warfarin to herbal supplements and pediatric risks, these articles show how safety isn’t a one-time stamp—it’s a continuous conversation between patients, doctors, and the system watching over them.