Olmesartan

What is Olmesartan?

Olmesartan, sometimes known by the brand name Olmetec, is a prescription-only medicine used to treat high blood pressure (hypertension). It belongs to a class of drugs called angiotensin II receptor antagonists, which help relax blood vessels and lower blood pressure[1]. 

What is olmesartan used to treat?

Olmesartan is primarily used to[1]: 

• Treat high blood pressure in adults and children aged 6 to under 18 years 

• Reduce the risk of cardiovascular events such as heart attacks and strokes by lowering blood pressure 

How does olmesartan work?

Olmesartan blocks the action of a substance in the body called angiotensin II, which normally causes blood vessels to narrow. By blocking this effect, olmesartan[1]: 

• Relaxes blood vessels 

• Lowers blood pressure 

• Improves blood flow 

Who can take olmesartan?

Olmesartan is suitable for adults with high blood pressure, as well as children aged 6 to 17 under specialist supervision. However, you should speak to your doctor or pharmacist first if you[1]: 

• Are allergic to olmesartan or any of its ingredients 

• Are pregnant, trying to get pregnant, or breastfeeding 

• Have bile duct or gallbladder problems like blocked bile ducts or gallstones  

• Have heart or liver problems 

• Have ever been on a low-salt diet 

• Have recently had severe diarrhoea or been vomiting 

• Have low blood pressure 

• Have diabetes or kidney problems, including recent transplants, and are taking medicines containing aliskiren 

Please tell your doctor or pharmacist about any conditions you may have or medication you take before you start treatment, and always follow the instructions in the Patient Information Leaflet[2].  

What is the typical dosage of olmesartan?

Olmesartan comes as 10mg, 20mg, and 40mg tablets. Typical doses include[1]: 

• Adults: 10mg once daily, potentially increasing to 20mg or 40mg if needed 

• Children (6-18 years): Dose depends on weight and is determined by a specialist 

After a few weeks, you will have blood pressure checks and potentially blood tests to check how well the medicine is working. Your doctor can then decide to change your dose if necessary. Always follow your pharmacist or doctor’s instructions[1]. 

How do you take olmesartan?

Take once daily, with or without food. Swallow the tablet whole with water. Try to take it at the same time each day[1]. 

Can you stop taking olmesartan?

Do not stop taking olmesartan without consulting your doctor or pharmacist. Stopping suddenly can cause your blood pressure to rise again, increasing the risk of heart attack or stroke[1]. 

What do you do if you take too much olmesartan?

If you take too much olmesartan[1]: 

• You may feel dizzy, lightheaded, or faint 

• Seek medical attention immediately or call NHS 111 

What do you do if you forget to take olmesartan?

Take it as soon as you remember. If it’s nearly time for your next dose, skip the missed dose. Do not take a double dose[1]. 

How should I store olmesartan?

Store below 25°C. Keep in the original packaging and keep out of sight and reach of children[1]. 

What medicines can’t you take with olmesartan?

There are some medicines that should be used with caution or avoided when taking olmesartan. You should speak to your doctor or pharmacist first if you’re already taking[1]: 

• Other blood pressure medicines (e.g. ACE inhibitors, ramipril, lisinopril, captopril, enalapril, aliskiren) 

• NSAIDs (e.g. ibuprofen, naproxen, diclofenac, aspirin, celecoxib) – may reduce effectiveness and harm kidneys 

• Lithium – risk of toxicity 

• Heparin for blood clots 

• Spironolactone for heart failure 

• Colesevelam for lowering cholesterol  

• Potassium supplements or diuretics  

Always inform your doctor or pharmacist about all medications and supplements you take before you start a new medicine, and follow the instructions in the Patient Information Leaflet[2]. 

What are the side effects of olmesartan?

Common side effects (may affect up to 1 in 10 people) include[1]: 

• Dizziness 

• Headache 

• Tiredness 

• Flu-like symptoms 

• Pain in back, bones, or joints 

• Indigestion 

• Stomach ache 

• Swollen limbs 

• UTIs 

• Nausea 

• Diarrhoea 

Serious side effects may include[1]: 

• Severe abdominal pain (possible intestinal problem) or diarrhoea 

• Yellowing of skin or eyes (liver issues) 

• Rash or tiny reddish-purple spots under the skin 

• Bruising or bleeding problems 

• Blood in your pee 

You should contact your GP if you experience any of these symptoms. In rare cases, the medicine may cause a serious allergic reaction (anaphylaxis). You should call 999 or visit A&E immediately if you believe this is happening[1]. 

Symptoms of anaphylaxis include[1]:  

• Difficulty breathing  

• Tightness in throat and chest  

• Swelling of the tongue or throat  

• Feeling faint or dizzy  

• Blue/grey skin or lips  

• Loss of consciousness 

If you experience any side effects, including those not listed, you are encouraged to report them via the Yellow Card Scheme or contact your doctor, pharmacist, or nurse. This information is intended as a summary for general awareness and does not replace professional medical advice. 

The information provided in the side effects section is not a comprehensive list of all possible side effects associated with this medication. For a complete list of side effects, please refer to the Patient Information Leaflet (PIL) provided with your medication or consult your healthcare professional[2]. 

Frequently asked questions about olmesartan

How long does olmesartan take to work? 
Blood pressure may start to lower within 1-2 weeks, with full effect in about 8 weeks[1]. 

Can I drink alcohol while taking olmesartan? 
Yes, but alcohol can increase the risk of dizziness or fainting[1]. 

Is olmesartan safe during pregnancy? 
No. It should not be used during pregnancy due to risk of harm to the baby and effects on development[1]. 

Can I take olmesartan with food? 
Yes, it can be taken with or without food[1]. 

Is olmesartan a diuretic? 
No, but it may be combined with a diuretic in some formulations[1]. 

Can I take olmesartan long-term? 
Yes, it is safe for long-term use under medical supervision[1]. 

What should I do if I feel dizzy after taking it? 
Sit or lie down until the feeling passes. This side effect will reduce over time. However, if it persists, contact your doctor[1]. 

For the official British National Formulary (BNF) guide to olmesartan, visit their website.