Pilot phase for the Tension-type HeadAche Prevention Project (HAPPy Too) to investigate in a double-blind, randomised trial whether treatment with low-dose blood pressure (BP) lowering therapy on top of standard care will reduce tension-type headache compared to placebo and standard care.

INTERVENTION: The HAPPy Too trial is a double‐blind randomised controlled trial in participants with frequent episodic tension‐type headache (TTH). The duration of the trial is 16 weeks in total (12 weeks of treatment + 4 weeks of observation) with an additional 4‐week screening period prior to randomisation. The 4‐week screening period will record number of headache days in that month and laboratory test results to confirm eligibility to receive study treatment. All eligible participants will be randomised and followed for a period of 16 weeks. The treatment period will be for 12 weeks. Unblinding will be avoided by using a uniform medication procedure for all groups. Randomised participants who deviate from the protocol/ and or discontinue allocated BP intervention will still be followed up to 16 weeks as their data will be analysed on the ‘intention to treat’ principle. The 13 and 16 week follow ups will assess for rebound headache and hypertension. During the 12‐week treatment period, participants will be randomised to one of two arms: low‐dose combination of telmisartan (20mg), amlodipine (2.5mg) and indapamide (1.25mg) OR placebo. Participants will take one capsule orally, daily. The capsule will either be a low‐dose combination (telmisartan + amlodipine + indapamide) or placebo. To maximise participant’s adherence to the study medications the following processes will be implemented: • Participant education during all visits on the importance of taking study medication, including timing, storage and what to do in the event of a missed dose • Participants will be instructed to return unused capsules at visit 5, week 12, and returned capsules will be counted by the study team. • Reminder text messages to commence study treatment after randomisation • Participants will be encouraged to contact a member of the study team if for any reason they are unable to continue their study medication or have missed multiple doses and are unsure whether to continue. CONDITION: Tension‐type Headache PRIMARY OUTCOME: The change from baseline in mean monthly TTH days at 12 weeks. SECONDARY OUTCOME: Change from baseline in health‐related quality of life (HRQoL) ‐ assessed through the use of Headache Impact Test‐6 (HIT‐6) Change from baseline in monthly lost productive work days due to TTH Change from baseline in monthly TTH medication treatment days ; (Medication treatment day is defined as any day in which the patient takes medication other than study medication to treat their TTH.) Change from baseline in the number of reduced productivity work hours per month Change in DBP and SBP Medication Adherence: Self‐reported measures ‐ participants will inform study personnel if they have missed any doses or misplaced any capsules. Participants will be instructed to return unused capsules at each follow up visit (visit 3‐5), and returned capsules will be counted by the study team. Proportion of subjects with at least a 50% reduction from baseline in monthly TTH days Safety: Percentage with any severe adverse event (SAE) ; Self reported by participants during follow up visits. ; An SAE is defined as any untoward medical occurrence that at any dose: ; • Results in death ; • Results in persistent or significant disability or incapacity ; • Results in congenital anomaly or birth defect (note that the females in the study population are likely to be post‐menopausal) ; INCLUSION CRITERIA: • Frequent episodic TTH according to the diagnostic criteria of the IHS • 2‐14 days per month with headache averaged over past 3 months (90‐days), as self‐reported by subject • Headache must have been present for >=1 year prior to enrollment in the study. • Onset of symptoms must have occurred before the age of 50 years ; • Is life threatening in the opinion of the attending clinician (i.e. The patient was at risk of death at the time of the event; it does not refer to an event that might hypothetically have caused death had it been more severe) ; • Requires inpatient hospitalisation or prolongation of existing hospitalisation (any hospitalisation that was planned prior to randomisation will not meet sae criteria. Any hospitalisation that is planned post‐randomisation will meet the SAE criteria) ; • Is an important medical event in the opinion of the attending clinician that is not immediately life‐threatening and does not result in death or hospitalisation but which may jeopardise the patient or may require intervention to prevent one of the other outcomes listed above ; The change from baseline in mean monthly hours with TTH Tolerability ‐ Difference between groups in participant withdrawals from treatment Tolerability ‐ Difference between groups in potentially‐related side‐effects (dizziness, blurred vision, syncope/ collapse/ fall, ankle oedema, skin rash, itching, gout, hyperkalaemia, hypokalaemia, hyponatraemia, rebound hypertension) • Adults between 18 and 65 years • Office SBP >=130mmHg and/or DBP >=80 mmHg • No definite contraindications to any of the study medications at the doses used in this trial. (Subjects can be taking other preventive and therapeutic medications as long as they do not contraindicate study medication. Patients will not be eligible if they are taking medications from the same class as the study treatments) • Is medically stable as determined by the Study Investigator • If the patient has concomitant migraine attacks, he/she must be able to differentiate between TTH and migraine. The frequency of migraine attacks must not e