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Hydrochlorothiazide (By mouth)

Treats high blood pressure and fluid retention (edema). This medicine is a diuretic (water pill).

What works?

Learn more about the effects of these drugs. The most reliable research is summed up for you in our featured article.

Hydrochlorothiazide is used alone or together with other medicines to treat high blood pressure (hypertension). High blood pressure adds to the workload of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. This can damage the blood vessels of the brain, heart, and kidneys, resulting in a stroke, heart failure, or kidney failure. High blood… Read more
Brand names include
Aquazide H, Hydrocot, Microzide, Zide
Drug classes About this
Cardiovascular Agent
Combinations including this drug

What works? Research summarized

Evidence reviews

[Meta-analysis on effectiveness and safety of irbesarten/hydrochlorothiazide combination therapy in treatment of essential hypertension]

Bibliographic details: Wu HD, Xu GL, Qin L.  [Meta-analysis on effectiveness and safety of irbesarten/hydrochlorothiazide combination therapy in treatment of essential hypertension]. Journal of Jilin University (Medicine Edition) 2011; 37(3): 517-522

Garlic for Hypertension

Garlic is widely used by patients for its blood pressure lowering effects. In this analysis, we reviewed the currently available evidence to determine the impact of garlic on cardiovascular events and mortality in patients with hypertension. Based on data from two randomized controlled trials that compared garlic to placebo in patients with hypertension it appears that garlic may have some blood pressure lowering effect, as compared to placebo but the evidence currently available is insufficient to determine whether garlic provides a therapeutic advantage versus placebo in terms of reducing the risk of cardiovascular morbidity and mortality. Data on the safety of garlic, as a therapeutic entity, in this population is also lacking. More (and large enough) trials comparing several doses of garlic with placebo are needed to detect possible differences in mortality, serious adverse events, and cardiovascular morbidity.

Efficacy and safety of delapril/indapamide compared to different ACE-inhibitor/hydrochlorothiazide combinations: a meta-analysis

The main objective of this meta-analysis was to compare the efficacy of the combination of delapril and indapamide (D+I) to different angiotensin-converting enzyme inhibitor (ACEi) plus hydrochlorothiazide (HCTZ) combinations for the treatment of mild-to-moderate hypertension. A secondary objective was to examine the safety of these two combinations. Studies comparing the efficacy of D+I to ACEi+HCTZ combinations in hypertensive patients and published on computerized databases (1974-2010) were considered. Endpoints included percentage of normalized patients, of responders, change in diastolic and systolic blood pressure (DBP/SBP) at different time-points, percentage of adverse events (AEs), and percentage of withdrawal. Four head-to-head randomized controlled trials (D+I-treated, n = 643; ACEi+HCTZ-treated, n = 629) were included. Meta-analysis indicated that D+I-treated patients had a higher proportion with normalized blood pressure (P = 0.024) or responders (P = 0.002) compared to ACEi+HCTZ-treated patients. No difference was observed between treatments on absolute values of DBP and SBP at different time-points. Although the rate of patients reporting at least one AE was similar in both groups (10.4% versus 9.9%), events leading to study withdrawal were lower in the D+I group versus the ACEi+HCTZ group (2.3% versus 4.8%, respectively; P = 0.018). This meta-analysis suggests that treatment with D+I could provide a higher proportion of normalized or responder patients with good tolerability compared to ACEi+HCTZ combinations.

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Summaries for consumers

Garlic for Hypertension

Garlic is widely used by patients for its blood pressure lowering effects. In this analysis, we reviewed the currently available evidence to determine the impact of garlic on cardiovascular events and mortality in patients with hypertension. Based on data from two randomized controlled trials that compared garlic to placebo in patients with hypertension it appears that garlic may have some blood pressure lowering effect, as compared to placebo but the evidence currently available is insufficient to determine whether garlic provides a therapeutic advantage versus placebo in terms of reducing the risk of cardiovascular morbidity and mortality. Data on the safety of garlic, as a therapeutic entity, in this population is also lacking. More (and large enough) trials comparing several doses of garlic with placebo are needed to detect possible differences in mortality, serious adverse events, and cardiovascular morbidity.

Diuretics effective in lowering blood pressure when given as a second drug

Diuretics are a good first‐line treatment for high blood pressure (BP). Diuretics include loop diuretics and thiazides. We asked how much do diuretics reduce BP when used as the second drug to treat hypertension. We performed a search of the available scientific literature to find all trial evidence to assess this question. Fifty‐six trials were found. Fifty‐three trials involved thiazide diuretics (92% with the drug hydrochlorothiazide) and included a total of 15310 participants. Adding a thiazide to another anti‐hypertensive drug further reduces the BP by an additional 6/3 mmHg when given at the starting dose and reduces BP by 8/4 mmHg at 2 times the starting dose. This is approximately the same effect as when the drugs are used alone. A good estimate of the harms associated with diuretics cannot be estimated in this review because of the lack of reporting and the short duration of the trials.

Thiazide diuretics for the treatment of high blood pressure

Thiazide diuretics are a class of drugs commonly recommended as first‐line treatment for raised blood pressure because they significantly reduce death, stroke and heart attacks. This class includes bendrofluazide, chlorthalidone, cyclopenthiazide, hydrochlorothiazide, indapamide and metolazone. We asked by how much does this class of drugs lower blood pressure and whether there is a difference between individual drugs within the class. We searched the available scientific literature to find all the trials that had assessed this question. The data included in this review was up to date as of February 2014.

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