Hydrochlorothiazide vs. Olmesartan
See how Hydrochlorothiazide and Olmesartan compare on approved uses, dosing, side effects, and cost.
Key Takeaways
Hydrochlorothiazide is a low-cost thiazide diuretic that lowers blood pressure by helping the kidneys remove excess salt and water, and it also treats fluid buildup from heart failure or liver disease.
Olmesartan is an ARB that relaxes blood vessels by blocking a hormone called angiotensin II, and it is approved only for hypertension, not fluid retention.
Both drugs are taken once daily by mouth, but hydrochlorothiazide costs far less out of pocket than olmesartan.
Hydrochlorothiazide vs. Olmesartan Drug Summary
Hydrochlorothiazide
Hydrochlorothiazide is a thiazide diuretic that lowers blood pressure and reduces fluid buildup by helping the kidneys excrete extra salt and water. It treats hypertension as well as edema from heart failure, cirrhosis, kidney problems, or steroid and estrogen use. It is taken as an oral tablet or capsule once a day.
Olmesartan
Olmesartan is an angiotensin II receptor blocker (ARB) that relaxes blood vessels by blocking a hormone that narrows them, lowering blood pressure. It is approved to treat hypertension in adults and children six and older, used alone or with other blood pressure medicines. It comes as an oral tablet taken once a day.
Hydrochlorothiazide vs. Olmesartan Side Effects
Hydrochlorothiazide
Olmesartan
Hydrochlorothiazide vs. Olmesartan Dosage
Hydrochlorothiazide
Olmesartan
| STAGE | DOSE | WHEN |
| Starting dose | 25 mg once daily | At the start |
| Maximum dose | 25-100 mg once daily | If needed |
| Dose changes | 2 increases | As tolerated |
| STAGE | DOSE | WHEN |
| Starting dose | 10 mg once daily | At the start |
| Maximum dose | 40 mg once daily | Week 3 onward |
| Dose changes | 2 increases | As tolerated |
Hydrochlorothiazide
| STAGE | DOSE | WHEN |
| Starting dose | 25 mg once daily | At the start |
| Maximum dose | 25-100 mg once daily | If needed |
| Dose changes | 2 increases | As tolerated |
Olmesartan
| STAGE | DOSE | WHEN |
| Starting dose | 10 mg once daily | At the start |
| Maximum dose | 40 mg once daily | Week 3 onward |
| Dose changes | 2 increases | As tolerated |
Hydrochlorothiazide vs. Olmesartan Indications
Hydrochlorothiazide
Hydrochlorothiazide is FDA-approved for high blood pressure, either alone or combined with other blood pressure drugs. It also treats fluid retention linked to heart failure, liver cirrhosis, kidney disease, and long-term steroid or estrogen use.
Treats high blood pressure
Treats edema from heart failure
Treats edema from liver cirrhosis
Treats edema from kidney disease
Olmesartan
Olmesartan is FDA-approved to treat high blood pressure in adults and children six years and older. It can be used alone or combined with other antihypertensive medicines, but it is not recommended as the first therapy in patients 75 or older or with liver problems.
Treats high blood pressure in adults
Treats high blood pressure in children 6+
Can be combined with other blood pressure drugs
Not for first-line use over age 75
Hydrochlorothiazide vs. Olmesartan Pros and Cons
Hydrochlorothiazide
Hydrochlorothiazide has decades of safety data and works for both blood pressure and fluid retention, making it useful beyond hypertension alone. It is inexpensive and widely covered by insurance, though it can cause meaningful electrolyte shifts that need monitoring.
Pros
Also treats edema, not just high blood pressure
Roughly $4 to $35 per month without insurance, far less than olmesartan
Decades of clinical use and well-established safety data
Can be combined with potassium-sparing diuretics to offset electrolyte loss
Cons
Can cause hypokalemia, hyponatremia, and other electrolyte problems needing blood tests
Raises blood sugar and uric acid levels
Long-term use linked to higher risk of non-melanoma skin cancer
Not recommended during pregnancy
Olmesartan
Olmesartan targets a single pathway in blood pressure regulation and generally causes fewer electrolyte disturbances than a diuretic. It carries a boxed warning against use in pregnancy and needs caution in people prone to high potassium or low blood volume.
Pros
Fewer electrolyte disturbances than a diuretic
Approved for children 6 years and older
Doses above 40 mg show no added benefit, simplifying dosing
Once-daily dosing with no advantage to splitting doses
Cons
Roughly $115 to $205 per month without insurance, much pricier than hydrochlorothiazide
Boxed warning for fetal toxicity in pregnancy
Risk of hyperkalemia, especially with kidney issues
Sprue-like enteropathy (severe diarrhea and weight loss) reported with delayed onset
Common Symptoms and Related Diseases You Can Explore
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