Which painkillers are best for acute pain after surgery?

For pain after surgery, which painkillers are most likely to help and least likely to harm? Sarah Chapman looks at the Cochrane evidence.

Page last checked 24 August 2022.

After any sort of operation, most people are going to have some pain, right? No problem, you say, that’s what painkillers are for. But which? There’s an array of painkillers available but it’s important to know which are most likely to work and least likely to harm us.

The Cochrane Pain, Palliative and Supportive Care Group (PaPaS) has brought together evidence from all the relevant Cochrane Reviews in two overviews, one on the effects venous of Single dose oral analgesics for acute postoperative pain in adults (published September 2015) and one on their safety – Adverse events associated with single dose oral analgesics for acute postoperative pain in adults (published October 2015).

Investigating which painkillers give the best pain relief

Sad and happy face made of pills
There is reliable Cochrane evidence on which oral painkillers are most effective and safe for acute pain after surgery

From the 39 Cochrane Reviews of oral painkillers, which involved around 50,000 people in 450 studies, the team found reliable evidence on the effectiveness of 53 pairs of drug and dose in all types of surgery. They also found that for some medicines the evidence is unreliable or lacking, which is also important to know.

The effectiveness of the drugs was assessed by the number of people who had at least half the maximum possible pain relief, compared with placebo (dummy pill), expressed as the ‘number needed to treat’ (NNT). The NNT is an estimate of how many people need to have the treatment for one person to have a good outcome. The lower the NNT, the more effective the painkiller is considered to be. This can be helpful when considering treatment options. How long pain relief lasted was also reported.

For the detail of all the drugs investigated you’ll need to go to the full overview, but here are some key points:

  • Fixed dose combination painkillers and fast acting formulations were among the more effective drugs e.g. ibuprofen 200 mg plus paracetamol 500 mg had an NNT of 1.5. Ibuprofen 200 mg plus caffeine 100 mg, ibuprofen 200 mg in a fast acting formulation and diclofenac potassium 50 mg (also fast acting) all had an NNT of 2.1
  • Even the most effective drugs fail to give good pain relief to a proportion of people, more than half the people treated in many instances
  • For 17 drugs, the evidence is absent or unreliable; none of these are in common use to treat acute pain
  • Useful head-to-head comparisons between drugs were not available

Which are most and least likely to cause adverse events?

Evidence from around 35,000 people in 350 studies provides evidence on adverse events (unwanted effects). The PaPaS team notes that most people in the studies had wisdom teeth removed, were relatively young and fit, and likely to take painkillers only occasionally. Adverse events may be different in people who are less well, older, or who take painkillers for several days or longer. They also tell us that patient diaries recorded more adverse events than other methods of collecting this information, but that “meta-analysis should provide good information on relative increases or decreases compared with placebo”.

Here’s what they found:

  • Similar rate of adverse events with most non-steroidal anti-inflammatory drugs (including ibuprofen, aspirin and disclofenac), paracetamol, and combinations of drugs that do not contain opioids (like codeine) as with placebo
  • More adverse events with aspirin 1000 mg, opioids, or fixed dose combinations containing opioids, than with placebo
  • Fewer adverse events with a combination of paracetamol and ibuprofen than with placebo
  • Serious adverse events were rare (about 1 in 3200 people)

Where does that leave us?

There is reliable evidence about the effectiveness of a large number of drugs for acute pain. Simple drug combinations and fast acting formulations can give good pain relief at relatively low doses and serious adverse events are rare. It should be remembered that even the most effective painkiller won’t work for some people but that a different one might!

You might also like this blog How Well Do Over-The-Counter Painkillers Work?


Moore RA, Derry S, Aldington D, Wiffen PJ. Single dose oral analgesics for acute postoperative pain in adults – an overview of Cochrane reviews. Cochrane Database of Systematic Reviews 2015, Issue 9. Art. No.: CD008659. DOI: 10.1002/14651858.CD008659.pub3.

Moore RA, Derry S, Aldington D, Wiffen PJ. Adverse events associated with single dose oral analgesics for acute postoperative pain in adults – an overview of Cochrane reviews. Cochrane Database of Systematic Reviews 2015, Issue 10. Art. No.: CD011407. DOI: 10.1002/14651858.CD011407.pub2.


Which painkillers are best for acute pain after surgery? by Sarah Chapman

is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International

4 Comments on this post

  1. The people who say no to pain meds.have never had real pain have never had a surgery go wrong.first one 2004 went threw the front of my neck. c4c5 6/7.cut a hole in throt. put a plate in then after 10 yrs 2 srews our backing out.then surgery on my knee two times. then surgery on my neck. that hurt like hell . then doc went in and sharped my shoulder upper bone. not working..i have all my mri/s. hope you can read what i/m writing.just told i have neuropathy.. hurting ever day is taking a toll on me. GOD BLESS. RONNIE H.

    Ronnie L Horne / Reply
  2. this post is a service to the community, tnks. Pain killers must be used with rationality

    Analgesico / Reply
  3. Nice post!!!
    Painkillers should be checked before taking. We should know about all its prescription. Follow the info and take proper pain killers. Thank you for information.

    Painsense / Reply
  4. What about the latest findings from Cochrane that paracetemol is mostly ineffective for acute pain, and is not as safe as alternatives? The blog does say that useful head to head comparisons were not given, so in fact the effectiveness (or not) of paracetemol on its own has not been studied in this context. Perhaps there should be a reference to the latest evidence that paracetemol is ineffective should be included in this blog so that professionals try removing it from the established combination treatments, or to test if it makes ibuprofen more effective as it seems to be the case with caffeine. http://uk.cochrane.org/news/paracetamol-widely-used-and-largely-ineffective.

    Caroline Struthers / Reply

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