Should you take painkillers for running?

Personally, I don't take painkillers for running. I barely take them at all, really, except when I'm hungover and need to pretend I'm a functional human being. Even then, I feel vaguely guilty about it, like I'm cheating my way through consequences I deserve.

When it comes to running, I've always had this half-baked idea that running is the painkiller. Got a headache? Run it off. Legs feel weird? Run anyway. Something vaguely wrong that you can't quite identify? Probably just needs a 10K to sort itself out. Does this make any physiological sense? Probably not. Does it get me out the door? Absolutely.

But plenty of runners do take painkillers before, during, or after running. Some swear by pre-race ibuprofen. Others pop paracetamol mid-marathon like they're collecting stamps. And for some people, it probably is fine. But my thinking has always been: if painkillers reduce the pain you feel, how do you know when something is actually going wrong? Pain is annoying, but it's also information: dull it too much and you might not notice the signal until it's too late.

Why runners take painkillers in the first place

The logic is straightforward. You have a niggle, or you're worried about getting one. Or you know from experience that mile 18 is going to hurt and you'd like to pre-emptively soften the blow. Painkillers feel like a practical solution - they're legal, easy to access, and socially acceptable. No one side-eyes you for carrying a blister pack of ibuprofen.

Some runners treat them like race-day insurance. Others use them for recovery, hoping to reduce inflammation and speed up the process. A surprising number take them before long runs "just in case," which is essentially admitting you expect your body to complain and you'd rather not hear about it. To be fair, long runs can absolutely be brutal, even without adding kidney stress to the mix.

The problem is that masking pain doesn't stop the thing causing the pain. It just makes you less aware of it, which can turn a manageable issue into something much worse.

Ibuprofen and endurance running

Ibuprofen is the drug most runners reach for, and it's also the one with the most evidence stacked against it when combined with endurance exercise.

Kidney stress

Your kidneys are already working hard during long runs. Blood flow to the kidneys decreases because your body is prioritising muscles, heart, and lungs. Add ibuprofen into the mix and you're compounding the problem. Ibuprofen reduces blood flow to the kidneys even further, which can impair their ability to filter waste and regulate fluid balance.

In extreme cases, it leads to acute kidney injury. Most runners won't experience full kidney failure, but even mild impairment increases the risk of dehydration, electrolyte imbalances, and post-race nausea. There are documented cases of runners ending up in hospital after marathons because they combined ibuprofen with dehydration and prolonged effort.

Gut issues

Ibuprofen irritates the stomach lining. Combine that with the reduced blood flow to your gut during running (because, again, your body is busy elsewhere) and you've created an environment where gastrointestinal distress is almost guaranteed. This can range from mild nausea to full-blown vomiting or diarrhoea mid-race.

If you've ever wondered why some runners look genuinely distressed around mile 20, there's a decent chance pre-race ibuprofen is part of the story. Though plenty of other things can go wrong on race day too.

It doesn't actually help performance

Multiple studies have shown that ibuprofen does not improve running performance. It doesn't make you faster, delay fatigue or reduce muscle soreness in any meaningful way. What it does is create the illusion that you're fine, which might make you push harder than you should, increasing your risk of injury.

Pain during a run is not always a sign of tissue damage, but it is a signal. Ignoring that signal because you've chemically muted it is not the same as addressing the underlying issue. If you're struggling to tell the difference between normal training pain and actual injury, this might help.

What about paracetamol?

Paracetamol (acetaminophen) is generally considered safer than ibuprofen for runners, but it's not without risk.

It doesn't have the same kidney or gut issues as NSAIDs like ibuprofen, which makes it a better option if you're going to take something. However, paracetamol is metabolised by the liver, and endurance exercise already places some strain on the liver. In high doses or combined with dehydration, paracetamol can cause liver damage.

The bigger issue with paracetamol is the same as ibuprofen: it reduces pain perception without addressing the cause. If your knee hurts because your IT band is tight, taking paracetamol and running anyway doesn't fix the tightness. It just delays the inevitable.

Which painkillers are actually safe?

None of them are completely safe when combined with endurance running, but if you're going to take something, paracetamol is the least risky option. Avoid ibuprofen, aspirin, and other NSAIDs entirely before or during long runs or races.

If you're using painkillers for recovery after a run, timing is key. Taking ibuprofen immediately post-run can interfere with the inflammatory response, which is part of how your muscles adapt and repair. If you must take something, wait at least a few hours, and prioritise rest, hydration, and protein instead.

When painkillers might actually make sense

There are situations where taking painkillers for running is reasonable, even if not ideal.

If you have a chronic condition that causes pain unrelated to running (arthritis, for example), and your doctor has advised you to take painkillers as part of your management plan, that's different. You're not masking an acute injury; you're managing a known issue.

If you've got a headache or mild illness and you're doing an easy, short run, paracetamol is unlikely to cause problems. The risks associated with NSAIDs and endurance exercise are dose-dependent and effort-dependent. A 5K at an easy pace is not the same as a marathon.

But if you're taking painkillers to get through a hard session or a race because you're worried about pain, that's a sign you should either adjust your expectations or address the underlying issue before you start.

Why I don't bother

I avoid painkillers because I want to know what my body is telling me. Pain is annoying, but it's also useful. If my knee starts complaining 10K into a long run, I'd rather know about it so I can decide whether to slow down, adjust my gait, or call it a day.

Masking that signal feels reckless. Not because I think I'm more sensible than other runners, but because I know I'm not. If I don't feel the pain, I'll ignore the problem, and by the time it becomes impossible to ignore, I'll have turned a minor niggle into something that keeps me off my feet for weeks.

That said, I'm also aware this might just be paranoia dressed up as caution. Plenty of runners take painkillers without issue. Some do it strategically and successfully. But the evidence suggests that for most people, most of the time, the risks outweigh the benefits.

The smarter approach

If you genuinely need painkillers to function, you probably need rest, not another run. And if you're taking them "just in case," you're solving a problem that doesn't exist yet, which is a surprisingly efficient way to create new problems.

Pain signals are not your enemy. They're inconvenient, annoying, and occasionally panic-inducing, but they exist for a reason. Muting them doesn't make you tougher. It just makes you less informed.