olmesartan
Brand names: Benicar
Olmesartan and hydrochlorothiazide is a drug that lowers high blood pressure. It contains two medicines that work together to help relax your blood vessels and remove extra salt and water from your body.
Drug Pricing (NADAC)
Brand Price
$10.27/unit
Generic Price
$0.08/unit
Generic Savings
99%
Generic Available
Yes (31 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
This medicine is used to treat high blood pressure (hypertension).
Common side effects
Nausea, High uric acid levels in the blood, Dizziness
Key warnings
This medicine can harm your unborn baby.
How It Works
Olmesartan blocks a substance in your body that tightens blood vessels, so blood flows more smoothly. Hydrochlorothiazide is a diuretic, which helps your body get rid of extra salt and water. This lowers blood pressure.
How to Take It
Take this medicine once a day. Your doctor may start you on 40/12.5 mg daily if olmesartan alone isn't working. If hydrochlorothiazide alone isn't working, your doctor may start you on 20/12.5 mg daily. Your doctor may increase your dose to 40/25 mg if needed. You can take this medicine with or without food.
Pregnancy & Breastfeeding
Do not use this medicine if you are pregnant. It can cause serious harm or death to your unborn baby, especially during the second and third trimesters. Talk to your doctor about other blood pressure medicines if you are breastfeeding or plan to breastfeed, as this medication may pass into breast milk.
Missed Dose
If you miss a dose, take it as soon as you remember. If it is close to your next dose, skip the missed dose and continue with your regular schedule.
Storage
Store this medicine at room temperature (68-77ºF).
Serious Warnings
This medicine can harm your unborn baby. If you are pregnant or plan to become pregnant, tell your doctor right away. Stop taking this medicine as soon as you know you are pregnant.
Known Drug Interactions
7.4 Dual Blockade of the Renin Angiotensin System Dual blockade of the RAS with angiotensin receptor blockers, ACE inhibitors, or aliskiren is associated with increased risks of hypotension, hyperkalemia, and changes in renal function (including acute renal failure) compared to monotherapy. Do not co-administer aliskiren with olmesartan medoxomil and hydrochlorothiazide in patients with diabetes [see Contraindications (4) ]. Avoid use of aliskiren with olmesartan medoxomil and hydrochlorothiazide in patients with renal impairment (GFR <60 ml/min).
Mechanism: Both drugs block the same system that controls blood pressure, which can put too much strain on your kidneys. This increases the risk of dangerously low blood pressure and high potassium levels.
What to do: Avoid using these medicines together, especially if you have diabetes or kidney disease. Your doctor will need to check your blood and kidney health often.
7 DRUG INTERACTIONS Lithium: Risk of lithium toxicity ( 7.2 ) Non-Steroidal Anti-Inflammatory Drugs (NSAIDs): Reduced diuretic, natriuretic and antihypotensive effects; increased risk of renal toxicity ( 7.3 ) Dual inhibition of the renin-angiotensin system: Increased risk of renal impairment, hypotension, and hyperkalemia ( 7.4 ) Colesevelam hydrochloride: Consider administering olmesartan at least 4 hours before colesevelam hydrochloride dose ( 7.5 ) Antidiabetic drugs: Dosage adjustment may be required ( 7.6 ) Cholestyramine and colestipol: Reduced absorption of thiazides ( 7.6 ) 7.1 Age...
Mechanism: Both drugs work to lower blood pressure, which can increase the risk of your blood pressure dropping too low or your kidney function changing.
What to do: Your doctor should monitor your blood pressure and kidney health regularly while you are taking this combination.
7 DRUG INTERACTIONS Lithium: Risk of lithium toxicity ( 7.2 ) Non-Steroidal Anti-Inflammatory Drugs (NSAIDs): Reduced diuretic, natriuretic and antihypotensive effects; increased risk of renal toxicity ( 7.3 ) Dual inhibition of the renin-angiotensin system: Increased risk of renal impairment, hypotension, and hyperkalemia ( 7.4 ) Colesevelam hydrochloride: Consider administering olmesartan at least 4 hours before colesevelam hydrochloride dose ( 7.5 ) Antidiabetic drugs: Dosage adjustment may be required ( 7.6 ) Cholestyramine and colestipol: Reduced absorption of thiazides ( 7.6 ) 7.1 Age...
Mechanism: Olmesartan can make it harder for your kidneys to remove lithium from your body, which can lead to dangerously high lithium levels.
What to do: Your doctor should check your lithium blood levels frequently to prevent toxicity.
7 DRUG INTERACTIONS Lithium: Risk of lithium toxicity ( 7.2 ) Non-Steroidal Anti-Inflammatory Drugs (NSAIDs): Reduced diuretic, natriuretic and antihypotensive effects; increased risk of renal toxicity ( 7.3 ) Dual inhibition of the renin-angiotensin system: Increased risk of renal impairment, hypotension, and hyperkalemia ( 7.4 ) Colesevelam hydrochloride: Consider administering olmesartan at least 4 hours before colesevelam hydrochloride dose ( 7.5 ) Antidiabetic drugs: Dosage adjustment may be required ( 7.6 ) Cholestyramine and colestipol: Reduced absorption of thiazides ( 7.6 ) 7.1 Age...
Mechanism: Colesevelam can stick to olmesartan in your stomach, which prevents your body from absorbing the blood pressure medicine correctly.
What to do: You should take your olmesartan dose at least 4 hours before you take colesevelam.
7 DRUG INTERACTIONS Lithium: Risk of lithium toxicity ( 7.2 ) Non-Steroidal Anti-Inflammatory Drugs (NSAIDs): Reduced diuretic, natriuretic and antihypotensive effects; increased risk of renal toxicity ( 7.3 ) Dual inhibition of the renin-angiotensin system: Increased risk of renal impairment, hypotension, and hyperkalemia ( 7.4 ) Colesevelam hydrochloride: Consider administering olmesartan at least 4 hours before colesevelam hydrochloride dose ( 7.5 ) Antidiabetic drugs: Dosage adjustment may be required ( 7.6 ) Cholestyramine and colestipol: Reduced absorption of thiazides ( 7.6 ) 7.1 Age...
Mechanism: Cholestyramine can trap other medicines in your gut, which prevents your body from absorbing them properly. This can make your blood pressure medicine less effective.
What to do: You should talk to your doctor about how to time your doses. They may suggest taking your blood pressure medicine at least 4 hours before the cholestyramine.
Common Questions
Can I start taking this medication on my own if I have high blood pressure?
What should I do if I feel dizzy after taking this medicine?
Can I drink alcohol while taking this medicine?
Will this medicine cure my high blood pressure?
Can I take this medicine if I am allergic to sulfa drugs?
Does this medicine interact with other medications I am taking?
How long does it take for this medicine to lower my blood pressure?
Can I stop taking this medicine if my blood pressure is normal?
Are there any lifestyle changes I should make while taking this medicine?
Can I use salt substitutes while taking this medicine?
What are the common side effects of olmesartan?
Does olmesartan interact with other medications?
What drug class is olmesartan?
Is there a generic version of olmesartan?
Is olmesartan safe during pregnancy?
Related Medications in Angiotensin II Receptor Blocker (ARB)
Other drugs grouped near olmesartan — same-class peers and common alternatives.
acebutolol
Sectral
Acebutolol is a medicine that helps lower blood pressure and control irregular heartbeats.
Compare with olmesartan →
aliskiren
Tekturna
Tekturna is a medicine used to treat high blood pressure.
Compare with olmesartan →
amiloride
Midamor
Amiloride is a water pill that helps your body hold onto potassium.
Compare with olmesartan →
amlodipine
Norvasc
Amlodipine (Norvasc) is a drug that lowers blood pressure and treats chest pain.
Compare with olmesartan →
amlodipine/benazepril
Lotrel
Lotrel is a combination medicine that contains amlodipine and benazepril.
Compare with olmesartan →
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What the FDA Data Shows for olmesartan
The FDA label for olmesartan (sold under brand names such as Benicar) classifies it as a prescription-only medication in the Angiotensin II Receptor Blocker (ARB) class. This medicine is used to treat high blood pressure (hypertension). Official labeling lists 4 commonly reported side effects, including Nausea, High uric acid levels in the blood, Dizziness.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. Voluntary reports accumulate over the lifetime of a drug and reflect wide-ranging clinical use. The database also lists 7 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated major severity. NADAC pricing from CMS shows a generic unit cost of $0.08 versus $10.27 for the brand — a 99% generic savings.
Report counts do not establish causation — a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice — always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: January 19, 2026
Read our methodology — how this data is sourced, computed, and verified.
All federal data sources used on this page
- FDA Orange Book — approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed — NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) — post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm — standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files — federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database — current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages