400mg vs. 600mg of Ibuprofen? Here's what ER doctors actually recommend

Toothache, a stiff back after a day in the garden, a headache that won’t shift: it can be tempting to reach for the strongest ibuprofen you can find. If there’s a 600 mg tablet left over from a prescription, it may seem obvious that it should work better than 400 mg.

But when experts actually compared the doses, that wasn’t what they found.

What happened when 400, 600, and 800 mg were compared

One of the clearest tests involved 225 adults being treated for acute pain in a US emergency department. Researchers randomly gave them a single dose of 400, 600, or 800 mg of ibuprofen. After 60 minutes, pain had fallen by a similar amount in all three groups. The researchers concluded that the three doses provided similar short-term pain relief.

A separate randomized study from researchers at the University of Oslo tested ibuprofen after wisdom-tooth surgery. It compared doses including 400, 600, and 800 mg and similarly found no significant increase in the painkilling effect when the ibuprofen dose went above 400 mg.

That doesn’t mean ibuprofen stops working at 400 mg. It means that, for the types of acute pain studied, increasing the single dose did not produce better pain relief.

Why taking more isn’t automatically better

Ibuprofen belongs to a group of medicines called NSAIDs. Like other NSAIDs, it can cause side effects involving the stomach, kidneys and cardiovascular system, and those risks become more important in people who are older or have certain existing health problems.

That is one reason official guidance emphasizes using the lowest effective dose for the shortest possible time. Dutch guidance, for example, recommends 400 mg as a starting dose for fever and general pain in adults and people over 12 who weigh more than 40 kg. If necessary, 200 to 400 mg can then be taken every four to six hours, with a maximum of 1,200 mg a day for this use. For acute pain, paracetamol is generally the first-choice painkiller, with an NSAID such as ibuprofen considered when appropriate.

So why do doctors prescribe 600 mg or more?

This is where the “400 mg is enough” message needs some context.

The studies above looked at single doses for acute pain. Ibuprofen also has an anti-inflammatory effect, and doctors may prescribe larger total daily doses for conditions involving significant inflammation.

For example, considerably higher daily doses may be prescribed for conditions such as rheumatoid arthritis and some other inflammatory disorders. Those are medically supervised treatment regimens, not instructions for treating an everyday headache or sore back yourself.

So if your doctor has prescribed 600 mg ibuprofen, these studies are not a reason to change that dose on your own.

What this means for the ibuprofen in your cupboard

The useful takeaway is surprisingly simple: a stronger tablet doesn’t automatically mean stronger pain relief.

For common acute pain, the available trials suggest that moving from 400 mg to 600 or even 800 mg in a single dose may add no meaningful benefit, and might, in fact, have long-term negative health consequences. Taking leftover high-dose prescription tablets for a different complaint therefore isn’t a sensible shortcut.

Follow the dose on the package or prescription and stay within the recommended daily maximum. If you have a history of stomach ulcers, kidney or heart problems, take blood-thinning medication, are pregnant, or regularly need painkillers, ask a doctor or pharmacist whether ibuprofen is suitable for you.

And if you have been prescribed a higher dose, keep following that prescription unless the healthcare professional treating you advises otherwise.