Non‐prescription (OTC) oral analgesics for acute pain ‐ an overview of Cochrane reviews Stable (no update expected for reasons given in 'What's new')

Abstract

Abstract
Background

Non‐prescription (over‐the‐counter, or OTC) analgesics (painkillers) are used frequently. They are available in various brands, package sizes, formulations, and dose. They can be used for a range of different types of pain, but this overview reports on how well they work for acute pain (pain of short duration, usually with rapid onset). Thirty‐nine Cochrane reviews of randomised trials have examined the analgesic efficacy of individual drug interventions in acute postoperative pain.

Objectives

To examine published Cochrane reviews for information about the efficacy of pain medicines available without prescription using data from acute postoperative pain.

Methods

We identified OTC analgesics available in the UK, Australia, Canada, and the USA by examining online pharmacy websites. We also included some analgesics (diclofenac potassium, dexketoprofen, dipyrone) of importance in parts of the world, but not currently available in these jurisdictions.

We identified systematic reviews by searching the Cochrane Database of Systematic Reviews (CDSR) on The Cochrane Library through a simple search strategy. All reviews were overseen by a single review group, had a standard title, and had as their primary outcome numbers of participants with at least 50% pain relief over four to six hours compared with placebo. From individual reviews we extracted the number needed to treat for an additional beneficial outcome (NNT) for this outcome for each drug/dose combination, and also calculated the success rate to achieve at least 50% of maximum pain relief. We also examined the number of participants experiencing any adverse event, and whether the incidence was different from placebo.

Main results

We found information on 21 different OTC analgesic drugs, doses, and formulations, using information from 10 Cochrane reviews, supplemented by information from one non‐Cochrane review with additional information on ibuprofen formulations (high quality evidence). The lowest (best) NNT values were for combinations of ibuprofen plus paracetamol, with NNT values below 2. Analgesics with values close to 2 included fast acting formulations of ibuprofen 200 mg and 400 mg, ibuprofen 200 mg plus caffeine 100 mg, and diclofenac potassium 50 mg. Combinations of ibuprofen plus paracetamol had success rates of almost 70%, with dipyrone 500 mg, fast acting ibuprofen formulations 200 mg and 400 mg, ibuprofen 200 mg plus caffeine 100 mg, and diclofenac potassium 50 mg having success rates above 50%. Paracetamol and aspirin at various doses had NNT values of 3 or above, and success rates of 11% to 43%. We found no information on many of the commonly available low dose codeine combinations.

The proportion of participants experiencing an adverse event were generally not different from placebo, except for aspirin 1000 mg and (barely) ibuprofen 200 mg plus caffeine 100 mg. For ibuprofen plus paracetamol, adverse event rates were lower than with placebo.

Authors' conclusions

There is a body of reliable evidence about the efficacy of some of the most commonly available drugs and doses widely available without prescription. The postoperative pain model is predominantly pain after third molar extraction, which is used as the industry model for everyday pain. The proportion of people with acute pain who get good pain relief with any of them ranges from around 70% at best to less than 20% at worst; low doses of some drugs in fast acting formulations were among the best. Adverse events were generally no different from placebo. Consumers can make an informed choice based on this knowledge, together with availability and price. Headache and migraine were not included in this overview.

Author(s)

R Andrew Moore, Philip J Wiffen, Sheena Derry, Terry Maguire, Yvonne M Roy, Laila Tyrrell

Abstract

Plain language summary

 Oral painkillers available without prescription for acute pain 

Acute pain is often felt soon after injury, and is of short duration. Most people who have surgery have moderate or severe pain afterwards. Painkillers (analgesics) are tested in people with pain, often following the removal of wisdom teeth. Study participants have to have at least moderate pain levels and the pain is usually treated with painkillers taken by mouth. This overview is useful mainly for acute pain lasting only a few days or weeks, and not for chronic pain lasting for many months. For this overview we have not included information from reviews on migraine, tension headache, or period pain.

In May 2015 we looked on pharmacy websites for the range of painkillers available in the UK that could be taken by mouth, and available without a doctor's prescription. We also looked at websites in Australia, Canada, and the USA. We then looked for Cochrane reviews reporting about how well these painkillers worked, and any side effects. We used high quality evidence from 10 Cochrane reviews supplemented with information from one non‐Cochrane analysis.

The outcome we used for successful treatment was that of people with moderate or severe pain having at least 50% of the maximum possible pain relief, over a period of about six hours. This is an outcome that people with acute and chronic pain, and headache, think is useful to them.

Combinations of ibuprofen plus paracetamol worked in 7 out of 10 (70%) people, and fast acting ibuprofen formulations 200 mg and 400 mg, ibuprofen 200 mg plus caffeine 100 mg, and diclofenac potassium 50 mg worked in over 5 out of 10 (50%) people. Dipyrone 500 mg, which is available OTC in many parts of the world, also worked in about 5 out of 10 people. Paracetamol plus aspirin at various doses worked in 1 out of 10 (11%) to 4 out of 10 (43%) people. An important finding was that low doses of some medicines in fast acting formulations were among the best. We could find no information on many of the commonly available combinations containing low doses of codeine. Taking painkillers with food may reduce how well they work.

There were fewer side effects for people taking ibuprofen plus paracetamol than those taking placebo (a pretend treatment). The results for side effects may be different if the painkillers are taken for more than a few days.

Author(s)

R Andrew Moore, Philip J Wiffen, Sheena Derry, Terry Maguire, Yvonne M Roy, Laila Tyrrell

Reviewer's Conclusions

Authors' conclusions

Implications for practice
For people with acute pain

The major implication for people with acute pain is the knowledge that there is a body of reliable evidence about the efficacy of some of the most commonly available drugs and doses that are available without prescription. The proportion of people with acute pain who get good pain relief with any of them ranges from about 70% at best to less than 20% at worst. Low doses in fast acting formulations can provide good analgesia in many people. Adverse events are generally no different from placebo. Consumers can make an informed choice based on this knowledge, together with availability, and price.

Advice is often given to take analgesics with food, with the ostensible aim of reducing adverse effects in the gastrointestinal tract, and this advice needs urgent re‐evaluation.

For clinicians

There is also a clear message that simple drug combinations and fast acting formulations deliver good analgesia in many people with acute pain, and at relatively low doses. Clinicians can use this knowledge to provide good evidence‐based advice to people who want to self medicate. There are no drugs available with prescription that are more effective.

Advice is often given to take analgesics with food, with the ostensible aim of reducing adverse effects in the gastrointestinal tract, and this advice needs urgent re‐evaluation.

For policy makers

Simple drug combinations and fast acting formulations can deliver good analgesia in many people with acute pain at relatively low doses. This can help provide potentially useful public health messages about maximising pain relief while minimising population exposure to analgesics.

Advice is often given to take analgesics with food, with the ostensible aim of reducing adverse effects in the gastrointestinal tract, and this advice needs urgent re‐evaluation.

For funders

The knowledge that no better analgesics are available with a prescription than without a prescription may have implications for prescribing policy and the health economy.

Implications for research
General

It appears to be possible to provide useful evidence‐based information directed at consumers concerning commonly used drugs available without prescription. That this is based on an in‐depth understanding of clinical trials and systematic reviews, consistently done to high quality levels, and using a simple message about outcomes of value to people with pain, provides an exemplar for how more can be done to inform consumers.

The lack of any information on the efficacy of low dose codeine combination therapies is a major gap in knowledge. While the doses of codeine may be small in individual doses, this possibly represents substantial population consumption, and we need to know that there is some benefit in terms of analgesic efficacy in individuals as a balance to possible harm to the community.

Design

Perhaps the most important design issue relates to the outcome. The outcome used is one of value to people with pain, and results can be expressed in a simple and understandable way.

Measurement (endpoints)

Pain measurement is not an issue.

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