Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

BACKGROUND: Aspirin has been known to be an effective analgesic for many years and is commonly used throughout the world for many different pain conditions. It is important for both prescribers and patients to have the best possible information about the efficacy and safety of analgesics, and this need is reflected in patient surveys which show that postoperative pain is often poorly managed. We also need to benchmark relative efficacy and safety of current analgesics so that we can compare them with new analgesics. OBJECTIVES: To quantitatively assess the analgesic efficacy and adverse effects of a single-dose of aspirin in acute pain of moderate to severe intensity. SEARCH STRATEGY: Randomised trials were identified by searching Medline (1966 to March 1998), Embase (1980 to January 1998), the Cochrane Library (Issue 1,1998) and the Oxford Pain Relief Database (1950 to 1994). SELECTION CRITERIA: The inclusion criteria used were: full journal publication, postoperative pain or a mixture of postoperative and acute trauma pain, oral administration, adult patients, baseline pain of moderate to severe intensity, double-blind design, and random allocation to treatment groups which compared aspirin with placebo. DATA COLLECTION AND ANALYSIS: Summed pain relief or pain intensity difference over four to six hours was extracted, and converted into dichotomous information yielding the number of patients with at least 50% pain relief. This was then used to calculate the relative benefit and the number-needed-to-treat (NNT) for one patient to achieve at least 50% pain relief. MAIN RESULTS: Seventy-two randomised single-dose trials met our inclusion criteria, with 3253 patients given aspirin, and 3297 placebo. Significant benefit of aspirin over placebo was shown for aspirin 600/650 mg, 1000 mg and 1200 mg, NNTs for at least 50% pain relief of 4.4 (4.0 to 4.9), 4.0 (3.2 to 5.4) and 2.4 (1.9 to 3.2) respectively. Single-dose aspirin 600/650 mg produced significantly more drowsiness and gastric irritation than placebo, with a number-needed-to-harm (NNH) of 28 (19 to 52) and 38 (22 to 174) respectively. Type of pain model, pain measurement, sample size, quality of study design, and study duration had no significant impact on the results. REVIEWER'S CONCLUSIONS: Aspirin is an effective analgesic for acute pain of moderate to severe intensity with a clear dose-response. Drowsiness and gastric irritation were seen as significant adverse effects even though the studies were single-dose. The pain relief achieved with aspirin was very similar milligram for milligram to that seen with paracetamol.


Journal article


Cochrane database of systematic reviews (Online)

Publication Date