Olmesartan belongs to the class of medications called angiotensin II receptor blockers. It is used to reduce blood pressure by blocking the actions of a chemical (angiotensin II) that causes blood vessels to constrict or tighten. It is used to treat mild to moderate high blood pressure. Your blood pressure may start to decrease within 1 to 2 weeks of starting this medication. Olmesartan may be used alone or in combination with a diuretic (water pill).

When blood pressure is allowed to remain high for a long time, the blood vessels of the heart, kidneys, and brain may become damaged. This puts a person at increased risk for heart attack and stroke as well as kidney failure and blindness. Keeping blood pressure in the normal range can reduce the risk for these conditions.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

For adults, the usual recommended starting dose of olmesartan is 20 mg once daily. Your doctor may recommend a dose increase of olmesartan to 40 mg daily if your blood pressure remains too high. Olmesartan may be taken with or without food, but should be taken in the same manner each day.

For children between the ages of 6 and 16 years, the usual dose is based on weight. Children weighing between 20 kg and 35 kg should receive 10 mg once daily up to a maximum of 20 mg daily. The dose for children weighing more than 35 kg is 20 mg once daily, which may be increased to a maximum of 40 mg daily. Olmesartan may be taken with or without food, but should be taken in the same manner each day.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important that this medication be taken exactly as prescribed by your doctor. If you miss a dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

20 mg
Each white, circular, film-coated tablet, with "D1" debossed on one side, contains 20 mg of olmesartan. Nonmedicinal ingredients: lactose monohydrate, microcrystalline cellulose low substituted hydroxypropyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, magnesium stearate, titanium dioxide, and talc.

40 mg
Each white, oval, film-coated tablet, with "466" debossed on one side, contains 40 mg of olmesartan. Nonmedicinal ingredients: lactose monohydrate, microcrystalline cellulose low substituted hydroxypropyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, magnesium stearate, titanium dioxide, and talc.

Do not use olmesartan if you:

• are allergic to olmesartan or any ingredients of the medication
• have diabetes or kidney disease and are taking aliskiren
• are pregnant or may become pregnant
• are breastfeeding

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• back pain
• constipation
• decreased appetite
• diarrhea
• dizziness
• headache
• nausea
• restlessness
• upper respiratory tract infection (such as colds or sinus infections)
• vomiting
• weakness

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• blood in the urine
• chest pain
• chronic diarrhea with weight loss
• fainting or severe dizziness (low blood pressure)
• flu-like illness (e.g., runny nose, sore throat, cough)
• increased occurrence of infections (e.g., flu-like illness, bronchitis, fever, chills)
• joint pain or swelling
• muscle cramps, spasms, or pain
• rash
• signs of heart problems (e.g., difficulty breathing when lying down, swelling feet or ankles, tiring easily)
• signs of kidney problems (e.g., decreased urination, nausea, vomiting, swelling of the feet and ankles)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• symptoms of bronchitis (e.g., shortness of breath, weakness, high fever, coughing, fatigue, wheezing)
• signs of too much potassium in the body (e.g., irregular heartbeat, muscle weakness, generally feeling unwell)
• spinning sensation
• swelling in the arms and hands or feet, ankles, and legs
• unexplained muscle pain, weakness, or dark brown urine

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of a serious allergic reaction (swelling of face, lips, tongue, or throat; hives; difficulty breathing)
• signs of kidney failure (e.g., no urine being produced; swelling legs, ankles, arms and hands; shortness of breath; irregular heartbeat; nausea; vomiting; loss of appetite)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin taking a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should take this medication.

Drowsiness/reduced alertness: Blood pressure medications may cause drowsiness or dizziness. Avoid driving or operating machinery until you know whether the medication affects you in this way.

Kidney disease: Olmesartan may affect the function of the kidneys, causing decreased kidney function, kidney failure, or possibly death. Certain people have experienced changes in kidney function (e.g., people with narrowed blood vessels in their kidneys, or those with severe congestive heart failure). The use of diuretics (water pills), nonsteroidal anti-inflammatory drugs (NSAIDs), or aliskiren may further increase risk of kidney problems for people already at risk for this problem. If you have kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver disease: Liver disease may cause olmesartan to be cleared more slowly from the body, resulting in increased side effects. If you have liver disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Low blood pressure: Occasionally, a greater-than-expected drop in blood pressure occurs after taking this medication. It is more likely to occur if you are taking additional diuretics (water pills), or aliskiren, have reduced salt intake, are on dialysis, have diarrhea, or are vomiting.

Your doctor may recommend that you have your blood pressure tested more often in these situations. To reduce the risk of dizziness, people with low blood pressure or those just starting to take this medication should stand or sit up slowly when getting up from a lying down or sitting position. If low blood pressure causes you to faint or feel lightheaded, contact your doctor.

Pregnancy: Babies born to parents who took olmesartan during pregnancy may develop birth defects. If you become pregnant while taking this medication, stop taking the medication and contact your doctor immediately.

Breast-feeding: It is not known if olmesartan passes into breast milk. If you are breast-feeding and taking this medication, it may affect your baby. Do not breast-feed while you are taking this medication.

Children: The safety and effectiveness of this medication have not been established for children less than 6 years of age.

There may be an interaction between olmesartan and any of the following:

• aldesleukin
• aliskiren
• alpha-blockers (e.g., alfuzosin, doxazosin, tamsulosin)
• amiodarone
• amphetamines (e.g., dextroamphetamine, lisdexamfetamine)
• angiotensin converting enzyme inhibitors (ACEIs; e.g., captopril, lisinopril, ramipril)
• other angiotensin receptor blockers (ARBs; e.g., candesartan, irbesartan, losartan)
• anti-psychotics (e.g., cariprazine, chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
• apomorphine
• barbiturates (e.g., butalbital, phenobarbital)
• bortezomib
• brigatinib
• brimonidine
• bromocriptine
• colesevelam
• diazoxide
• diuretics (water pills; e.g., bumetanide, furosemide)
• drospirenone
• duloxetine
• eplerenone
• finerenone
• flunarizine
• heparin and low-molecular weight heparins (e.g., dalteparin, tinzaparin)
• iron sucrose
• levodopa
• lithium
• methylphenidate
• monoamine oxidase inhibitors (MAOIs; e.g., phenelzine, rasagiline, selegiline, tranylcypromine)
• medications that increase the level of potassium in the blood (e.g., spironolactone, amiloride, triamterene, or salt substitutes that contain potassium)
• morphine
• nabilone
• nitrates (e.g., isosorbide dinitrate, isosorbide mononitrate, nitroglycerine)
• non-steroidal anti-inflammatory medications (NSAIDs; e.g., celecoxib, diclofenac, ibuprofen, naproxen)
• obinutuzumab
• pentoxifylline
• pergolide
• phosphodiesterase 5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
• polyethylene glycol
• potassium supplements
• pramipexole
• primidone
• ranolazine
• riociguat
• ropinirole
• rotigotine
• sacubitril
• sodium phosphates
• sotalol
• tacrolimus
• tizanidine
• tolvaptan
• tretinoin
• tricyclic antidepressants (e.g., clomipramine, imipramine)
• trimethoprim
• yohimbine

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.