in pictures and a few words
What it is and why it matters
Five painkillers are often lined up in a ranking: etoricoxib, diclofenac potassium, metamizole, naproxen and ketoprofen. Let’s look at what is really known about them.
- Each was tested against a dummy pill for severe pain after surgery
- The list is a good guide, but not a ranking of strength
- Choose by the situation, not by the place in the list
What is known for sure
In severe pain right after surgery, etoricoxib really does stand apart from the bottom of the list.
- In these studies it helped more often than naproxen and ketoprofen — this is confirmed
- Among diclofenac potassium, metamizole and naproxen, the order is not confirmed
- Etoricoxib is prescription-only: it is taken if a doctor has prescribed it
Tested in people. Tested in people with severe pain after surgery: etoricoxib standing apart from the bottom of the list is a real result.
Ketoprofen and toothache
With ketoprofen, the result depends on what hurts. For toothache it is on a par with the leader; after other operations it is noticeably weaker.
- This difference is confirmed; it is not chance
- The average figure in the ranking describes neither group
Diclofenac: check the salt
The pack says just one word, “diclofenac”, but the salt can differ. In acute pain the potassium salt gives a result about three times better than the sodium salt.
- The potassium salt helps well in acute pain
- The sodium salt, according to the review authors, is probably not worth using for acute pain
Naproxen works longer
Naproxen stays in the body longer than the others. It is taken twice a day, not three or four times.
- If the pain will last several days, this matters more than its place in the list
- The ranking doesn’t see this: it counts only the first hours after a single dose
What was actually tested
All the figures come from one situation: severe pain right after surgery — most often after a tooth extraction or surgery on bones and joints.
- One dose, not a course
- They watched for 4–6 hours: did the pain drop by at least half
- Headache, period pain and back pain were not studied here
Why this is not a ranking
Each drug was compared with a dummy pill in its own study — with its own people and its own operation. They were not compared with each other.
- You can put them side by side, but you can’t subtract one from another
- A difference is confirmed in only two pairs out of ten
- On these data, metamizole could turn out better or worse than its neighbours
The main rule
Never take two painkillers from this group at the same time. The pain relief does not add up, but the risk to the stomach, kidneys and blood pressure does.
- Stomach: damage and bleeding are possible with all of them; etoricoxib is gentler but not safe
- Blood pressure: they can raise it and weaken blood pressure medicines
- Heart: diclofenac carries a higher risk than some others
Who should see a doctor first
Over-the-counter packs are meant for days, not weeks. If the pain lasts longer, that is a reason to see a doctor, not to buy the next pack.
- Kidney disease, dehydration, older age: these drugs reduce blood flow to the kidneys
- High blood pressure and taking medicines for it
Important. Metamizole has a separate risk — a sharp drop in white blood cells. The signs that mean stopping it at once are in its own guide.
In one sentence
Choose by the situation, not by the place in the list, and don’t take two of them at once. A medicine that has already helped and was well tolerated is usually better.
- Toothache — ketoprofen; pain for several days — naproxen
- Diclofenac — the potassium salt, not sodium
In Brief
| Drug | NNT (95% CI) | What matters |
|---|---|---|
| Etoricoxib 120 mg | 1.8 (1.7–2.0) | Best figure; in the EU that dose is for gout only |
| Diclofenac potassium 50 mg | 2.1 (1.9–2.5) | The sodium salt gives 6.6 in the same setting |
| Metamizole 500 mg | 2.4 (1.8–3.1) | Thinnest evidence base; agranulocytosis |
| Naproxen 500/550 mg | 2.7 (2.3–3.2) | Lasts longer than the rest |
| Ketoprofen 50 mg | 2.9 (2.4–3.7) | The average misleads: 1.8 and 4.2 |
A painkiller ranking looks convincing: five names, five numbers, a clear order. Such a list is comfortable to live with — it answers the question «which is stronger».
The trouble is that the source of those numbers does not answer that question.
What Was Actually Measured
All five figures come from Cochrane single-dose reviews, and all describe the same thing:
- pain that is acute and postoperative — most often after tooth extraction or an orthopaedic procedure;
- a single dose, not a course;
- an observation window of four to six hours;
- the outcome being the proportion of patients whose pain fell by at least half compared with placebo;
- and almost everywhere that proportion was computed from the area under the relief curve rather than measured by asking.
Hence the first limitation, and it is a hard one. None of this transfers to headache, period pain or back pain. Not because the drugs fail there, but because these reviews hold no such data. The list describes one specific situation: severe pain right after surgery, in the first hours.
Why This Is Not a Ranking
All five reviews were gathered into one overview: 39 reviews, some 460 studies, roughly 50,000 participants. And it contains a sentence that devalues any ranking built on these figures:
«No statistical comparison was undertaken.»
The reason is simple. Each drug was compared with placebo in its own trial, with its own patients, its own operation and its own measurement. You can place the results side by side; you cannot subtract one from another.
You can check this yourself by looking at the confidence intervals. If they overlap, the difference is not established.
| Pair | Intervals | Difference |
|---|---|---|
| Etoricoxib and naproxen | 1.7–2.0 and 2.3–3.2 | established |
| Etoricoxib and ketoprofen | 1.7–2.0 and 2.4–3.7 | established |
| Etoricoxib and diclofenac | 1.7–2.0 and 1.9–2.5 | overlapping |
| Diclofenac and metamizole | 1.9–2.5 and 1.8–3.1 | overlapping |
| Metamizole and naproxen | 1.8–3.1 and 2.3–3.2 | overlapping |
| Naproxen and ketoprofen | 2.3–3.2 and 2.4–3.7 | overlapping |
In total: of the ten possible pairs, the difference is established in exactly two. Etoricoxib separates from the bottom of the list — that is a real result. Everything else is an order that looks like knowledge and is not.
Metamizole shows it most clearly: its interval of 1.8–3.1 spans both first place and last. On these data it could be better than diclofenac or worse than ketoprofen.
Where the Average Misleads
For two of the five, the headline figure describes arithmetic rather than a situation.
What the Table Does Not Measure at All
NNT is computed over six hours after a single dose. Everything that happens later falls outside it by construction.
So duration of action is invisible in the list. Naproxen's half-life is markedly longer than the others': it is taken twice a day rather than three or four times. For pain lasting days that changes more than a decimal place of NNT — yet naproxen still looks mid-table. That is covered separately.
The table misses something else too: availability. Etoricoxib, with the best figure, is prescription-only in all three countries, and in the EU its 120 mg dose — the very one that produced the 1.8 — is authorised only for an acute gout attack. Metamizole is not sold in France at all. Oral ketoprofen is prescription-only in Germany, while in Italy 68 of 105 packs are sold freely.
Safety — Common to All Five
- Stomach. The risk of erosions and bleeding belongs to the whole class; COX-2 selective agents such as etoricoxib are better tolerated but not safe.
- Kidneys. All NSAIDs reduce renal blood flow. Caution with dehydration, chronic kidney disease and in older age.
- Blood pressure. The class can raise it and blunt antihypertensive drugs.
- Heart. The risk is not uniform within the class: diclofenac carries more of it than some others.
- Duration. Over-the-counter packs are sized for days, not weeks. If pain outlasts them, that is a reason to see a doctor rather than to buy another box.
Metamizole adds a risk the others do not share — agranulocytosis. The signs that mean stopping at once, and what the regulator changed in December 2024, are covered in its guide.
How to Choose When the Table Has No Answer
| Situation | What is reasonable |
|---|---|
| Dental pain | Ketoprofen — in that subgroup its figure is at the leader's level |
| Severe short-lived pain after surgery | Etoricoxib, if a doctor has prescribed it |
| Pain that will last several days | Naproxen — a duration the others lack |
| Rapid relief needed in acute pain | Watch the salt: diclofenac potassium, not sodium |
| Another NSAID already started | Do not add a second under any circumstances |
And one rule worth ten tables: a drug that has already worked for you and was well tolerated usually beats one whose review figure is a tenth of a point prettier.
The Bottom Line
The five are a good orientation and a poor ranking. What genuinely follows from them is that etoricoxib separates from the bottom of the list in acute postoperative pain, that with diclofenac the salt decides, and that with ketoprofen the type of pain does. What does not follow is who is «strongest»: that comparison was never made.
And the most important limitation deserves repeating at the end, because it is the one most often lost: all these figures were measured in acute pain after surgery, after a single dose, over six hours. Your headache took no part in these reviews.
Detailed accounts of each drug: etoricoxib, diclofenac, metamizole, naproxen, ketoprofen.
Where to get them
All five are in the catalogue. No price is shown on the cards: prescription medicines are ordered through the chat, and the administrator confirms availability and cost.
Key facts
- All five figures come from one model: a single oral dose, acute POSTOPERATIVE pain, the proportion with pain at least halved over 4–6 hours versus placebo.
- The overview of 39 reviews (some 460 studies, 50,000 participants) states plainly: no statistical comparison between drugs was undertaken.
- Only two pairs in the five have non-overlapping intervals — etoricoxib versus naproxen and versus ketoprofen. Everything else overlaps.
- Ketoprofen's average of 2.9 describes nobody: 1.8 in dental pain against 4.2 in other surgery, and the difference is significant.
- For diclofenac what decides is not its rank but its salt: potassium 2.1 against sodium 6.6.
- None of it transfers to headache, period pain or back pain — those data do not exist in these reviews.
