Olmesartan
Pronunciation: pronunciation varies by local usage.
- Generic name
- olmesartan medoxomil
- Brand names
- Benicar
- Drug class
- Angiotensin II receptor blocker (ARB)
- Form
- Tablet, film coated
- Route
- Oral
- Legal status
- Prescription-only medicine
Availability and supply rules vary by country
Trade names by country: United States · Canada
Australia: · Full directory
What olmesartan medoxomil is and how it works
Olmesartan is an angiotensin II receptor blocker (ARB) used to treat hypertension (high blood pressure) in adults and children 6 years of age and older. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and heart attacks. (1)
Olmesartan is an oral tablet taken once daily. A clinician must determine the appropriate dose and monitor blood pressure periodically. Do not change the dose or stop treatment without medical advice.
Mechanism of action: how olmesartan medoxomil works
Olmesartan is an angiotensin II receptor blocker (ARB). (1)
What olmesartan medoxomil is used for
Hypertension
Olmesartan is indicated for the treatment of hypertension in adults and children 6 years of age and older, to lower blood pressure. Lowering blood pressure reduces the risk of cardiovascular events such as stroke and myocardial infarction. The exact dose and blood pressure goal are individualised by the prescriber. (1)
Before taking olmesartan medoxomil
Do not take / not appropriate for
- If pregnancy is suspected or confirmed while taking olmesartan, seek urgent medical assessment. The label states olmesartan should be discontinued as soon as pregnancy is detected; the treating clinician directs this and any other treatment decision. (all products) (1)
- Aliskiren must not be co-administered with olmesartan in patients with diabetes; the prescriber will select an alternative if needed. (patients with diabetes) (1)
Tell your clinician about
- If you are pregnant, planning to become pregnant, or breastfeeding.
- If you have kidney disease.
- If you have low blood pressure, heart failure, or volume depletion.
- If you are taking other blood pressure medicines, potassium supplements, salt substitutes containing potassium, NSAIDs, lithium, or colesevelam.
- If you have diabetes and are taking aliskiren.
- If you develop severe, persistent diarrhea or unintended weight loss.
How to take olmesartan medoxomil
- The recommended starting dose for adults is 20 mg once daily; dose range 20-40 mg once daily.
- For children 6 years and older: body weight 20 kg to under 35 kg — 10 mg once daily (range 10-20 mg); body weight 35 kg or more — 20 mg once daily (range 20-40 mg).
- Do not change the dose, frequency, or stop taking without consulting the prescribing clinician.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1)
Missed dose
Do not take an extra dose to make up for a missed one; ask the prescribing clinician for guidance.
Overdose
Not established from the sources reviewed: a specific overdose-management protocol was not established in the sources reviewed for this page beyond general supportive care. If an overdose is suspected, seek medical attention.
Side effects
Dizziness is the most common side effect (reported in about 3% of adult patients). Serious side effects, though uncommon, can occur and may require prompt medical attention.
Dizziness
What to notice: Feeling lightheaded or unsteady, especially upon standing or after a dose.
What to do: Sit or lie down until the dizziness passes. If dizziness persists, worsens, or causes fainting, contact the prescriber for assessment. (1)
Sprue-like enteropathy
What to notice: Severe, chronic watery diarrhea often leading to substantial weight loss. This may appear months to years after starting olmesartan.
What to do: Contact the prescribing clinician if these symptoms develop. Do not self-manage persistent diarrhea; a clinician will investigate and determine if olmesartan should be stopped. (1)
Hypotension (low blood pressure)
What to notice: Signs of low blood pressure.
What to do: Report these symptoms to the clinician. (1)
Hyperkalemia (high potassium)
What to notice: Signs of high potassium.
What to do: Contact the clinician for blood tests and advice. (1)
Renal impairment
What to notice: Signs of a change in kidney function.
What to do: Inform the clinician, who will assess kidney function. (1)
Angioedema
What to notice: Signs of angioedema.
What to do: Seek medical help. (1)
Serious warnings
Pregnancy — FDA BOXED WARNING: fetal toxicity — emergency
Symptoms: This is the medicine's FDA boxed warning, its most serious safety warning. There are often no symptoms: the risk is to a developing baby, not to the person taking the tablet. A missed or late period, a positive pregnancy test, or planning a pregnancy are the situations that matter.
Action: Tell your prescriber straight away if you become pregnant or think you might be. The label states that when pregnancy is detected olmesartan should be discontinued as soon as possible, because medicines acting directly on the renin-angiotensin system can cause injury and death to the developing fetus. Seek medical advice promptly and let the clinician you see advise on whether to continue or stop olmesartan and what to use instead. (1)
Angioedema — warning
Symptoms: Signs of angioedema.
Action: Contact a healthcare provider. Angioedema has been reported post-marketing with olmesartan and other ARBs; the treating clinician determines management. (1)
Sprue-like enteropathy — emergency
Symptoms: Severe, chronic watery diarrhea with substantial weight loss. This may occur months to years after starting treatment.
Action: Contact the prescribing clinician promptly. Stool tests and intestinal biopsies may be needed; a clinician will consider stopping olmesartan if no other cause is found. (1)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Potassium-elevating agents (e.g., potassium-sparing diuretics, potassium supplements, salt substitutes containing potassium) | May increase serum potassium levels, leading to hyperkalemia. | Ask your clinician before using these agents together with olmesartan; serum potassium should be monitored. (1) |
| Non-steroidal anti-inflammatory drugs (NSAIDs) and COX-2 inhibitors | Concomitant use may lead to deterioration of renal function, including possible acute renal failure, especially in volume-depleted patients. | Inform the prescriber about all NSAID or COX-2 inhibitor use. (1) |
| Dual blockade of the renin-angiotensin system (e.g., combining olmesartan with an ACE inhibitor or aliskiren) | Increased risk of hypotension, hyperkalemia, and changes in renal function compared with monotherapy. | Ask your prescriber about this combination; the treating clinician determines whether and how it is used. (1) |
| Lithium | Concomitant use with ARBs increases the risk of lithium toxicity. | Ask your clinician about lithium monitoring if used together with olmesartan. (1) |
| Colesevelam (a bile acid sequestrant) | Colesevelam reduces the systemic exposure of olmesartan. | Take olmesartan at least 4 hours before colesevelam. (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Children and adolescents (6 years and older)
Olmesartan is indicated for hypertension in children 6 years and older. Dosing is based on body weight: for those 20 kg to under 35 kg, the recommended starting dose is 10 mg once daily (range 10-20 mg); for those 35 kg or more, the starting dose is 20 mg once daily (range 20-40 mg). (1)
Pregnancy
The label carries a boxed warning: olmesartan should be discontinued as soon as pregnancy is detected. Drugs that act on the renin-angiotensin system can cause fetal injury and death; specific effects reported include fetal renal dysfunction, oligohydramnios, skeletal deformities, and neonatal death. If pregnancy is detected, seek urgent medical assessment; the treating clinician determines the treatment plan. (1)
Breastfeeding
Olmesartan is present in breast milk at low levels (based on animal studies). Because of the potential for serious adverse reactions in a breastfed infant, a decision should be made with your clinician whether to discontinue breastfeeding or discontinue olmesartan, taking into account the importance of the medicine for the mother. (1)
Patients with renal impairment
Renal function may change in susceptible patients (e.g., those with pre-existing kidney disease or severe heart failure), with a risk of acute renal failure. Individualisation by the prescriber is essential. (1)
Monitoring
Before starting
- Assess blood pressure and volume status.
- Check serum potassium.
- Review current medications for potentially interacting drugs (NSAIDs, lithium, colesevelam, other RAAS blockers).
During treatment
- Monitor blood pressure regularly.
- Monitor serum potassium.
- Watch for signs of hypotension, hyperkalemia, and angioedema.
- Ask about persistent diarrhea or unexplained weight loss; the treating clinician evaluates for sprue-like enteropathy if these occur.
Storage
Follow the product packaging.
Study the drug class: Angiotensin receptor blockers
Professional information
Clinician-facing context only. Use the current local prescribing information for detailed dosing, precautions, and indication-specific guidance.
United States
Indication: Hypertension
Dose summary: Adults: initial 20 mg once daily; dose range 20–40 mg once daily. Children 6 years and older: 10 mg once daily (20 to <35 kg) or 20 mg once daily (≥35 kg); dose range 10–20 mg or 20–40 mg, respectively. Dose individualisation based on blood pressure response and tolerability.
Renal context: No initial dosage adjustment is recommended in moderate to marked renal impairment (creatinine clearance below 40 mL/min). After repeated dosing the AUC approximately tripled in severe renal impairment (creatinine clearance below 20 mL/min). Monitor for worsening renal function. (1)
Hepatic guidance
No initial dosage adjustment is recommended in moderate to marked hepatic dysfunction. AUC increased by approximately 60% in moderate hepatic impairment versus matched controls.
Overdose note
Not established from the sources reviewed: a specific overdose-management protocol, antidote, or dialysis-effectiveness statement was not established in the sources reviewed for this page beyond general supportive care. (1)
Frequently asked questions
Can I take olmesartan if I am pregnant?
The label states olmesartan should be discontinued as soon as pregnancy is detected, because it can cause serious harm to the developing baby. If you become pregnant while taking olmesartan, seek urgent medical assessment; your clinician determines the treatment plan. (1)
What should I do if I have persistent diarrhea while taking olmesartan?
Contact your prescriber. Severe diarrhea with weight loss could be a sign of a rare condition called sprue-like enteropathy. Your clinician will evaluate and may need to stop olmesartan. (1)
How long does it take for olmesartan to lower blood pressure?
Do not discontinue or change the dose without your clinician's guidance. (1)
What is the mechanism of action of olmesartan medoxomil?
Olmesartan is an angiotensin II receptor blocker (ARB). (1)
What is the generic name of Olmesartan?
The generic name is olmesartan medoxomil. It is sold under brand names including Benicar. (1)
What class of drug is olmesartan medoxomil?
Olmesartan is classed as: Angiotensin II receptor blocker (ARB). (1)
References
- BENICAR (olmesartan medoxomil) tablet, film coated — full prescribing informationU.S. Food and Drug Administration (DailyMed) · United States · accessed 2026-08-05 · source 1
- OLMESARTAN MEDOXOMIL TABLET [NORTHSTAR RXLLC] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 2
- Amlodipine — patient drug information (MedlinePlus)U.S. National Library of Medicine (MedlinePlus) · US · accessed 2026-08-14 · source 3
- olmesartan medoxomil-hydrochlorothiazide — FDA approval record (Drugs@FDA NDA021532)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 4
- olmesartan medoxomil — RxNorm normalized drug concept (RXCUI 118463)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 5
Brand names by country
Single-ingredient olmesartan medoxomil names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- Benicar40 mg, 20 mg, 5 mg · cosette pharmaceuticals, inc.
Canada
- OLMETEC