Treating episodic tension-type headache with paracetamol
Tension-type headache is the most common form of headache. Tension-type headaches are called episodic tension-type headaches if they occur on less than half of the days in a month. Medications may help to those who have frequent tension-type headaches. Drugs like aspirin and paracetamol have usually been used to treat headaches. Aspirin works by binding and blocking an enzyme which helps in prostaglandins production. Paracetamol does not block the effects of the enzyme necessary for the production of prostaglandins, but it does inhibit the enzyme. Therefore, paracetamol is often suggested for acute treatment of headaches in frequent episodic tension-type headache.
To assess the efficacy and safety of paracetamol for frequent episodes of tension-type headache, a study was conducted. For search criteria, Cochrane Central Register of Controlled Trials (CENTRAL) (CRSO), MEDLINE, EMBASE and the Oxford Pain Relief Databases were selected. A list of references of relevant published studies and reviews were selected. Unpublished studies were also chosen by searching online clinical trial registers and manufacturer's websites.
In the study, 10 participants of age 18 years or over were selected. Total of 23 studies were included, in which 12 studies used the IHS diagnostic criteria or similar, 6 used older classification of the Ad Hoc Committee and 5 did not describe specific diagnostic criteria. The participants with migraine were excluded. Total 8079 people suffering with tension-type headache participated in the conducted study.
For IHS preferred outcome of being pain free at 2 hours, the NNT for paracetamol 1000 mg compared with placebo was 22 (95% confidence interval (CI) 15 to 40) in 8 studies (5890 participants; high quality evidence), with no significant difference from placebo at 1 hour. The NNT was 10 (7.9 to 14) for pain-free or mild pain at 2 hours in five studies (5238 participants; high quality evidence). The use of rescue medication was lower with paracetamol 1000 mg than with placebo, with an NNTp to prevent an event of 7.8 (6.0 to 11) in six studies (1856 participants; moderate quality evidence). On limited data, efficacy of paracetamol 500 mg to 650 mg was not superior to placebo, and paracetamol 1000 mg was not different from either ketoprofen 25 mg or ibuprofen 400 mg (low quality evidence).
No adverse events were noted between paracetamol 1000 mg and placebo. The quality of evidence using GRADE comparing paracetamol 1000 mg with placebo was moderate to high. After evaluation, it was concluded that paracetamol 1000 mg provided a small benefit in terms of being pain free at 2 hours for people with frequent episodic tension-type headache who have an acute headache of moderate or severe intensity.