MEDIA BRIEFING
23rd August 2005
Study shows aspirin and paracetamol reduce fever equally well
There is no significant difference in efficacy between aspirin and paracetamol
when they are used to treat fever and other symptoms associated
with viral upper respiratory tract infection (URTI),
according to a large international study(1).
This new, randomised, double-blind, placebo-controlled trial shows that, at single doses of 500 and 1,000 mg, both aspirin and paracetamol significantly reduce fever, headache and other symptoms in adults with URTI with a similar frequency of adverse events.
The efficacy of aspirin and paracetamol was so impressive that the study was ended prematurely because it was considered unethical to deny such effective treatment to participants by giving them a placebo.
This study clearly demonstrates that aspirin is highly effective in relieving fever and other symptoms of URTI in adults, and that it is well tolerated.
Why was the study carried out?
Aspirin and paracetamol are familiar household medicines for the treatment of colds and minor pains but there are few scientific comparisons of their effectiveness and tolerability.
There is a misconception that paracetamol is better at reducing fever and has fewer side effects than aspirin, and that aspirin is a superior analgesic.
This study was conducted to provide scientific evidence of the comparative efficacy and tolerability of these medicines in relieving the common symptoms of viral URTI.
Who were the participants?
The participants were chosen to be representative of people with a common cold. They were men and women aged between 18 and 65 who had a URTI and fever probably caused by a virus and lasting for no more than 5 days. Their symptoms included headache, aching, sore throat, cough, runny nose, chills and sweating. People were excluded if they had more serious illness (such as bacterial sinusitis or pneumonia) or were taking other medicines that might affect their symptoms.
How was the study carried out?
392 participants were randomly assigned to one of the treatments or placebo. Neither they nor the investigators were aware of which intervention they took. The interventions were single doses of placebo, aspirin 500 or 1,000 mg, or paracetamol 500 or 1,000 mg.
The main endpoint of the study was the total change in fever over the first 4 hours following the dose. Other endpoints included the extent and timing of fever relief and the severity of other symptoms. Fever was measured every 30 minutes for 6 hours. Participants noted the severity of other symptoms at 2, 4 and 6 hours. Adverse events were recorded throughout the study.
What was the main finding?
Both doses of aspirin and paracetamol reduced fever more than placebo and these differences were statistically significant. There was no difference between similar doses of aspirin and paracetamol.
What were the other findings?
The reduction in fever began 30 minutes after the dose and persisted for at least 6 hours for both doses of aspirin and paracetamol. The higher doses of each medicine achieved greater reductions in fever than the lower doses.
Aspirin 1,000 mg reached its peak effect on fever (lowered by 1.67°C) more quickly than paracetamol 1000 mg (lowered by 1.71°C) (time to maximum temperature difference 174 vs. 213 minutes).
Both doses of aspirin and paracetamol reduced headache severity throughout the study.
Achiness and feverish discomfort were reduced at all time points for the higher doses of both aspirin and paracetamol.
Neither medicine relieved sinus sensitivity and only aspirin 1,000 mg reduced the pain of sore throat.
During the study, half of participants assigned to placebo took 'rescue' medicine to relieve their symptoms compared with only 5% who took aspirin or paracetamol 1,000 mg.
Tolerability
All treatments were well tolerated and all adverse events were of mild to moderate intensity.
The overall frequency of adverse events in those who took placebo was 21.8%; this compared with 15.4% for aspirin 500 mg and 12.7% for paracetamol 500 mg, and 30.8% for aspirin 1,000 mg and 29.1% for paracetamol 1,000 mg. These differences were not statistically significant.
The frequency of adverse events that investigators believed could be attributed to treatment was 5.1% with placebo, 10.3% for aspirin 500 mg, 11.4% for paracetamol 500 mg, 29.5% for aspirin 1,000 mg and 25.3% for paracetamol 1,000 mg.
The differences between the higher doses of each drug and placebo were statistically significant. Adverse events included increased sweating and gastrointestinal events but these were not significantly more common with either drug than with placebo.
What does this study tell us?
Aspirin and paracetamol are both effective treatments for fever and they also relieve other symptoms of viral URTI such as headache. In both cases, a dose of 1,000 mg is more effective than a dose of 500 mg. These medicines act quickly (within 30 minutes) and their effects last for at least 6 hours.
There is no difference in tolerability between aspirin and paracetamol. Both treatments are well tolerated and adverse events of mild to moderate intensity are more frequent with the higher doses of each drug than with placebo.
- ENDS -
Reference
1. Bachert C, Chuchalin AG, Eisebitt R, Netayzhenko VZ, Voelker M. Aspirin compared with acetaminophen in the treatment of fever and other symptoms of upper respiratory tract infection in adults: a multicentre, randomized, double-blind, double-dummy, placebo-controlled, parallel-group, single-dose, 6-hour dose-ranging study. Clin Ther 2005;27:993-1003
