On the clinical side, tension-type headache has been defined as a multifactorial disorder, conceivably implying the need for tailored treatment strategies. Headache-related disability can usually be reduced by identifying and avoiding triggers combined with pharmacologic and non-pharmacologic treatment (such as relaxation and stress management techniques or physical therapies), but effective treatment modalities are still lacking. Particularly, symptomatic drugs are effective for episodes of TTH, whereas preventive treatment (indicated for frequent and chronic TTH) is, on average, barely effective, and do not display good tolerability. Patients are turning to complementary or alternative therapies for headaches, including osteopathic manipulative therapy (OMTh). One previous pilot study carried out by the investigators has suggested an efficacy for OMTh in frequent episodic TTH, that might represent an alternative treatment strategy to prophylactic drugs. Frequent episodic TTH (ETTH) was chosen for this study since it is the most common diagnostic category with indications for prophylactic drug management. To date there is no rigorously tested evidence that manual therapies in general have a positive effect on TTH, as many reviewers have found. Conflicting results in previous studies might be due both to the low number of clinical trials and an indiscriminate application of different techniques. Some studies, however, have demonstrated positive effects of manipulative therapy.