Abstract: The original review included six studies on tension-type headache. We now include eight studies with a total of 412 participants with chronic forms of tension-type headache. These studies evaluated five SSRIs (citalopram, sertraline, fluoxetine, paroxetine, fluvoxamine) and one SNRI (venlafaxine). The two new studies included in this update are placebo controlled trials, one evaluated sertraline and one venlafaxine. Six studies, already included in the previous version of this review, compared SSRIs to other antidepressants (amitriptyline, desipramine, sulpiride, mianserin). Most of the included studies had methodological and/or reporting shortcomings and lacked adequate power. Follow-up ranged between two and four months. Six studies explored the effect of SSRIs or SNRIs on tension-type headache frequency, the primary endpoint. At eight weeks of follow-up, we found no difference when compared to placebo (two studies, N = 127; mean difference (MD) -0.96, 95% confidence interval (CI) -3.95 to 2.03; I2= 0%) or amitriptyline (two studies, N = 152; MD 0.76, 95% CI -2.05 to 3.57; I2= 44%). When considering secondary outcomes, SSRIs reduce the symptomatic/analgesic medication use for acute headache attacks compared to placebo (two studies, N = 118; MD -1.87, 95% CI -2.09 to -1.65; I2= 0%). However, amitriptyline appeared to reduce the intake of analgesic more efficiently than SSRIs (MD 4.98, 95% CI 1.12 to 8.84; I2= 0%). The studies supporting these findings were considered at unclear risk of bias. We found no differences compared to placebo or other antidepressants in headache duration and intensity. SSRIs or SNRI were generally more tolerable than tricyclics. However, the two groups did not differ in terms of number of participants who withdrew due to adverse events or for other reasons (four studies, N = 257; odds ratio (OR) 1.04; 95% CI 0.41 to 2.60; I2= 25% and OR 1.55, 95% CI 0.71 to 3.38; I2= 0%). We did not find any study comparing SSRIs or SNRIs with pharmacological treatments other than antidepressants (e.g. botulinum toxin) or non-drug therapies (e.g. psycho-behavioural treatments, manual therapy, acupuncture). Since the last version of this review, the new included studies have not added high quality evidence to support the use of SSRIs or venlafaxine (a SNRI) as preventive drugs for tension-type headache. Over two months of treatment, SSRIs or venlafaxine are no more effective than placebo or amitriptyline in reducing headache frequency in patients with chronic tension-type headache. SSRIs seem to be less effective than tricyclic antidepressants in terms of intake of analgesic medications. Tricyclic antidepressants are associated with more adverse events; however, this did not cause a greater number of withdrawals. No reliable information is available at longer follow-up. Our conclusion is that the use of SSRIs and venlafaxine for the prevention of chronic tension-type headache is not supported by evidence.

Plain-language summary: This is an update of a previous review that included studies on migraine and tension-type headache. The original review has been split into two separate reviews: this update addresses only studies on tension-type headache, while a second focuses on migraine. When we updated this review (November 2014), we identified two new studies. Six studies were already included in the previous version of the review. Overall, we analysed a total of 412 adults participants. All the studies had a small number of participants and were conducted over a period of two to four months. Only a few were of high quality. Results suggest that SSRIs or SNRIs are no better than placebo (sugar pill) in reducing the number of days with tension-type headache. There were no differences in minor side effects between participants treated with SSRIs or SNRIs versus those treated with placebo. SSRIs and SNRIs do not seem to offer advantages when compared to other active treatments, specifically the tricyclic antidepressant, amitriptyline. The participants treated with SSRIs or SNRIs suffered fewer minor side effects than those who took amitriptyline, however the number of people who stopped taking one drug or the other due to side effects was approximately equal. These results are based on poor quality, small, short-term trials (no more than four months). We did not find a study comparing SSRIs or SNRIs with other medications (e.g. botulinum toxin) or non-drug therapies (e.g. psycho-behavioural treatments, manual therapy, acupuncture).