The purpose of this study is to evaluate the safety by assessing all serious and non-serious adverse events (AEs), irrespective of relatedness or expectedness, as well as other safety parameters including laboratory values, serious adverse events (SAEs)/serious adverse drug reactions (ADRs), unexpected AEs and ADRs that are not reflected on the precaution in the use, ADRs already known, non-serious ADRs and other safety related information (laboratory values changes, etc).

This is a long-term prospective, observational post-marketing surveillance study of azilsartan medoxomil/chlorthalidone FDC in participants with essential hypertension. The study will assess the safety and effectiveness of azilsartan medoxomil/chlorthalidone FDC prescribed as a monotherapy or taken concomitantly with other anti-hypertension therapies in participants whose blood pressure is not properly controlled by azilsartan medoxomil monotherapy or who require administration of multiple drugs in order to reach the target blood pressure in routine clinical settings.

The study will enroll and will consider approximately 600 participants. These participants will be grouped with the ones treated with azilsartan medoximil monotherpy. The data will be prospectively collected, at the centers from medical files and recorded into electronic case report forms (e-CRFs). All the participants will be assigned to a single observational cohort:

• Participants With Essential Hypertension

The multi-center study will be conducted in South Korea. Data collection will be based on routinely scheduled and emergency visits over the surveillance period, scheduled at Visit 1 (Baseline), Visit 2 (6 weeks), Visit 3 (at least 3 months to 6 months) and Visit 4 (6 months or more up to 9 months) after drug administration. The overall duration of the study will be approximately 5 years. All participants will be followed up for 9 months after drug administration.

Inclusion Criteria:

1. Has a SBP or DBP >=140 or 90 mmHg, respectively.
2. Newly prescribed azilsartan medoxomil/chlorthalidone FDC as an early therapy for participants whose blood pressure is not properly controlled by monotherapy with azilsartan medoxomil or who require administration of multiple drugs in order to reach the target blood pressure in participants with stage 2 hypertension.

Exclusion Criteria:

1. With anuria.
2. With refractory hypokalemia.
3. With severe hepatic or renal impairment (estimate glomerular filtration rate [eGFR] <30 milliliter per minute per 1.73 square meter [mL/min/1.73 m^2]).
4. With hyponatremia, hypercalcemia.
5. With symptomatic hyperuricemia (history of gout and urate stone).
6. With untreated Addison's disease.
7. Receiving lithium therapy.
8. Administrating terfenadine and/or astemizole.
9. Use of aliskiren in combination with study drug in participants with diabetes or with moderate to severe renal impairment (glomerular filtration rate [GFR] <60 mL/min/1.73m^2).
10. Participating in a clinical trial evaluating a hypertension treatment.
11. Treated with azilsartan medoxomil / chlorthalidone FDC outside of the locally approved label in South Korea.

Participants who have administered azilsartan medoxomil/chlorthalidone FDC as an early therapy for participants whose blood pressure is not properly controlled by monotherapy or who require administration of multiple drugs in order to reach the target blood pressure will be observed prospectively.

Takeda makes patient-level, de-identified data sets and associated documents available for all interventional studies after applicable marketing approvals and commercial availability have been received (or program is completely terminated), an opportunity for the primary publication of the research and final report development has been allowed, and other criteria have been met as set forth in Takeda's Data Sharing Policy (see www.TakedaClinicalTrials.com for details). To obtain access, researchers must submit a legitimate academic research proposal for adjudication by an independent review panel, who will review the scientific merit of the research and the requestor's qualifications and conflict of interest that can result in potential bias. Once approved, qualified researchers who sign a data sharing agreement are provided access to these data in a secure research environment.