Uncontrolled hypertension (HTN) is a major public health worldwide, which increases the risk of cardiovascular diseases. Low adherence to medication, unhealthy lifestyle and poor knowledge of HTN diagnosis and treatment are among the known factors associated with uncontrolled HTN. Digital innovations became popular as low-cost tools to provide personalized advice to people with long-term health conditions, leading to their adherence to health behavior modifications. Therefore, this randomized single-blind controlled trial (RCT) aimed to test whether providing health information via a short message service (SMS) influences blood pressure control, health practice, and medication adherence. For the current RCT, the investigators will use data from the PERSIAN Kavar cohort study (PKCS). Eligible participants with uncontrolled HTN will be randomly assigned to experiment (SMS) or control (routine care) groups at a 1:1 ratio. Participants in the experimental group will receive three messages/per week for three months. Systolic and diastolic blood pressure will be the primary outcomes of this study. Medication adherence and practice related to cardiovascular diseases will the secondary outcomes. These variables will be assessed before and after the intervention. At the end of the study, the acceptability of the messages will also be assessed.

Inclusion Criteria:

• Patients who have a diagnosis of HTN by a clinician at the baseline or until the third follow-up of PKCS, have uncontrolled HTN (≥140/90) at the enrollment, have a prescription for blood pressure-lowering medication, understand Persian, have regular access to a mobile phone, and are able to read SMS by themselves or with their family's help. The investigators will enroll only one member per household.

Exclusion Criteria:

• Those with renal failure or requiring specialist care for their hypertension at a hospital, pregnant women or who are within 3 months postpartum, patients with severe physical or mental illness, and subjects not willing to participate in the study.