The Drug Error That Changed How I Think About Safety

There are shifts you remember because everything goes right.

Then there are the ones you remember because they quietly change the way you practice forever.

This was one of those shifts.

It was the end of a long night shift. The morning staff were due in within ten minutes, and I was working in a busy resuscitation area. A patient needed a complex medication that I had never administered before. It carried significant risks if given incorrectly, so I did what I thought was the right thing.

I checked the medication chart.

I realised I wasn't familiar with the drug, so I opened the guideline and carefully read through the administration instructions.

The medication required a large loading dose followed by a much smaller continuous infusion. I worked through the calculations, wrote down the dose, and because I was the only nurse available, I asked the doctor to independently check my work.

She agreed with my calculation.

Together, we administered the medication over the recommended time.

Only afterwards did we realise something that made both of us stop.

I hadn't calculated the loading dose.

I'd accidentally calculated the infusion dose instead.

The doctor had looked at exactly the same numbers and reached exactly the same conclusion.

Neither of us recognised the mistake until after the medication had already been given.

The patient was fortunately monitored closely and, in the end, suffered no lasting harm. I still think about how differently that story could have ended.

For a long time, I wondered how two clinicians could both make the same mistake.

The answer wasn't a lack of knowledge.

It wasn't a lack of care.

It was something far more common.

Confirmation bias.

Once I believed my calculation was correct, every piece of information I looked at seemed to support it. The independent check wasn't truly independent. The doctor wasn't checking the calculation from scratch—she was checking whether my calculation looked reasonable. We both unconsciously validated the same incorrect assumption.

Fatigue probably played a role too.

It was the end of a night shift. We'd been making decisions for hours. Our brains were tired, and tired brains are more likely to accept information that fits the story they've already built.

I've often wondered what would have happened if we'd simply waited ten minutes for the incoming shift.

Fresh eyes.

Fresh minds.

No pressure to finish before handover.

Maybe nothing would have changed.

Or maybe everything would have.

That experience changed how I approach medication safety.

Now, whenever I calculate a medication—especially one that's unfamiliar—I try to imagine that no one else will ever check it. Not because I don't trust my colleagues, but because I understand how easily two people can share the same blind spot.

Independent checks are important.

But they only work when they're genuinely independent.

Most importantly, I learned that good clinicians make mistakes. Not because they're careless, but because they're human. We work in complex systems, often under pressure, frequently fatigued, and our brains take shortcuts without us even realising it.

The goal isn't to become perfect.

It's to recognise the conditions that make errors more likely and build habits that protect our patients when our brains inevitably let us down.

That shift didn't make me lose confidence.

It made me slower when it mattered.

More curious.

More willing to question my own thinking.

And I believe it made me a safer nurse.

Because sometimes the most important lesson isn't learning how to calculate a drug.

It's learning that your own mind can convince you that you're right when you're not.