Telmisartan and Hydrochlorothiazide (Oral)

Telmisartan and hydrochlorothiazide works by blocking a substance in the body that causes the blood vessels to tighten.


Telmisartan and hydrochlorothiazide (available under brand name Micardis HCT) is a combination of two medications into a single form. These medications work in different ways to lower an individual's blood pressure, hence reduce the risk of heart attack or stroke. However, it is important to note that this medication should not be your first consideration when treating high blood pressure. Only try telmisartan and hydrochlorothiazide combination if your blood pressure is not controlled with telmisartan or hydrochlorothiazide.

How telmisartan and hydrochlorothiazide works

Telmisartan works by blocking the angiotensin II hormone from getting into contact and binding to a receptor in the body, stopping the reactions that cause an increase in blood pressure from occurring. In a healthy person, angiotensin II plays a critical role in keeping the balance of blood pressure within normal range. More angiotensin II is produced when the pressure gets low, which increases the hormone's effect and help raise the blood pressure appropriately. The smooth muscles that surround blood vessels contract, narrowing the passageways as the kidney reabsorb more water to increase the blood volume. With more blood flowing through the thinner blood vessels, the pressure increases, restoring the body's normal balance.

When you take telmisartan, the ability of angiotensin II to activate the receptor is interrupted, hence the normal effects are unable to occur. As a result, the reverse happens:

  • The muscles surrounding the blood vessels relax to create more space for the blood flowing through
  • The kidneys reabsorb less water as the patient excretes more urine, reducing the volume of blood.

Less blood pumping through larger blood vessels means pressure will reduce. Think of a plumbing system, there will be less stress for the heart to pump blood around the body.

What you need to know when taking telmisartan and hydrochlorothiazide

There are a couple of things you should be aware of before starting telmisartan medication. Here are some of them:

  • Angioedema - swelling of the face and mouth, which can be particularly dangerous if the airways get blocked. You should contact your healthcare provider as soon as possible if this occurs.
  • Renal impairment - changes in the function of the kidney can result in renal impairment over time. This is common when telmisartan is used alongside other medications like diuretics and NSAIDS. Patients who have poor kidney functions should consider alternative medication for treating hypertension.
  • Stopping suddenly - some patients experience rebound hypertension with even higher blood pressure if they suddenly stop taking this medication. This is because the body has adapted to taking telmisartan on a daily basis. The patient should gradually reduce the dosage over several weeks to avoid rebound hypertension.

Conditions treated by telmisartan and hydrochlorothiazide

Type of medication

  • Angiotensin II receptor blocker (ARB)

Side effects of telmisartan and hydrochlorothiazide

Telmisartan and hydrochlorothiazide affects the body in different ways and there are a number of undesired effects associated with taking telmisartan, including:

Low blood pressure (hypotension)

The most common side effect of telmisartan occurs when the medication is working too well, to the extent that the patient ends up having low blood pressure. When this occurs, the patient may notice the following:

Hypotension is most common during the first few days of medication as well as when there is an increase in dosage. The condition usually improves as the body gets used to the medication, but if hypotension persists for over a week, then the patient should consider asking the doctor to adjust the dosage or change medication.

Excess potassium (Hyperkalaemia)

Telmisartan causes more water to be removed from the body via urine than usual. This can interfere with potassium balance in the body. As less potassium is excreted, there can be high levels in the body, making the patient feel generally weak and tired. If these signs are noticed, the doctor should ask for a blood test to check potassium levels and decide what to do.


Some people may get a dry cough when on telmisartan and hydrochlorothiazide medication. If this persists, alternative hypertension medications should be considered.

Other side effects

Lightheadedness and dizziness may occur during the first days of treatment before the body adjusts to medication. Some patients may also suffer from light diarrhea and general body tiredness. Inform your doctor promptly if these side effects persist or worsen. To reduce the risk of lightheadedness and dizziness, rise up slowly from a lying or sitting position.

Telmisartan and hydrochlorothiazide may cause dehydration (loss of excess body water). The patient may also lose a lot of salts and minerals. Inform your healthcare provider right away if you experience symptoms of dehydration and mineral loss such as very dry mouth, extreme thirst, muscle weakness and cramps, irregular or fast or low heartbeat, and confusion.

Inform your healthcare provider right away if you experience any serious side effects such as signs of kidney problems (such as change in quantity of urine), fainting, joint and muscle pains, symptoms of high potassium levels in the blood (such as slow/irregular heartbeats and muscle weakness), poor vision and eye pain.

Serious allergic reactions to telmisartan and hydrochlorothiazide are rare. However, seek medical attention right away if you notice any allergic reactions such as itching/ swelling (especially in the throat, tongue and face), rashes, breathing problems, and severe dizziness.

Always remember that your healthcare provider will prescribe this medication because they are convinced that the benefits far outweigh the risks and side effects. Most people using telmisartan and hydrochlorothiazide do not suffer from adverse side effects. Seek direction from your doctor about the side effects. You may also report these side effects to FDA at 1-800-FDA-1088 or online at

Telmisartan and hydrochlorothiazide dosage and administration

The patient whose blood pressure is not adequately controlled should be initiated with telmisartan monotherapy 80mg/12.5mg once per day. The dosage can be increased up to 160mg/25 mg after 2-4 weeks if required.

The patient whose blood pressure is not adequately controlled should be initiated by 25 mg of hydrochlorothiazide once per day. If the pressure is controlled but the patient experiences hypokalemia, then a combination medication of telmisartan 80 mg/12.5mg and hydrochlorothiazide 25 mg should be administered once per day. The dosage can be adjusted to 160mg/25mg after 2-4 weeks if required.

Telmisartan and hydrochlorothiazide may be administered in combination with other antihypertensive medications.

Dose adjustment for hepatic impairment

Patients with biliary obstructive disorders or hepatic insufficiency should be initiated with combination medication (telmisartan and hydrochlorothiazide) of 40 mg/12.5mg per day. This should be administered under close medical supervision. Telmisartan and hydrochlorothiazide medication is not recommended for patients with severe hepatic impairment.

Telmisartan and hydrochlorothiazide overdose

Symptoms of telmisartan and hydrochlorothiazide may include difficulty in breathing, severe dizziness, rapid heartbeat, and passing out. Call 911 immediately. You may also report telmisartan and hydrochlorothiazide overdose to the poison control center at 1-800-222-1222.

Telmisartan and hydrochlorothiazide interactions

Possible drug interactions

Serum potassium increasing agents

Co-administering telmisartan with other medication that increase serum potassium levels in the body may result in hyperkalemia. Serum potassium should be closely monitored in such patients.


Rise in serum lithium concentrations, as well as lithium toxicity, have been observed with concomitant use of thiazide diuretics or angiotensin II receptor antagonists such as telmisartan. Lithium levels should be closely monitored in patients on lithium and MICARDIS HCT medication.

This medication should never be co-administered with RAS inhibitors. Closely monitor renal function, blood pressure and electrolytes in patients on MICARDIS HCT and other agents that may affect RAS inhibitors.

Telmisartan and hydrochlorothiazide should never be co-administered with aliskiren to diabetic patients. At the same time, concomitant use of telmisartan with aliskiren should be avoided in atients with renal impairment.


Telmisartan co-administration with digoxin increases the digoxin peak plasma concentration as well as trough concentration. Digoxin levels should be closely monitored in patients on concomitant telmisartan and digoxin.

Antidiabetic medications (insulin and oral agents)

Dosage adjustments may be required for antidiabetic medications when they are co-administered with hydrochlorothiazide.

Cholestyramine and colestipol resins

The presence of anionic exchange resins impairs hydrochlorothiazide absorption. Consider staggering hydrochlorothiazide and resin doses such that hydrochlorothiazide is administered 4-6 hours before administering resin.

Loop diuretic

Taking loop diuretic medications in combination with telmisartan may increase the risk of renal impairment and blood pressure that is too low, especially during the first few doses. It is advisable to reduce the dose or stop taking loop diuretic medications for a few days to let the body adjust to telmisartan.


Telmisartan and NSAIDs can be co-administered to younger and healthy patients. However, this combination may not work well to reduce blood pressure in aging patients. The combination may also cause renal impairment in aging patients.

Pregnancy and breastfeeding

Telmisartan and hydrochlorothiazide should never be administered to women who are pregnant or are planning to conceive soon. This is because the medication can cause birth defects in early pregnancy or renal dysfunction to the unborn baby later in the pregnancy. Use effective birth control methods to avoid getting pregnant while on this medication.

It is also not recommended to take this medication while breastfeeding because there is inadequate information available on whether the medication can be passed through breast milk and its effect to the breastfeeding baby.

Foods, alcohol and tobacco

Some drugs may interact with certain foods, alcohol and tobacco. Find out from your healthcare provider whether you need to avoid certain foods, alcohol and tobacco while on this medication. Also, inform your healthcare provider of any other medications you are on, including prescribed and over-the-counter medications. Also, inform your doctor about any vitamins, supplements and herbal products you may be using.

Telmisartan and hydrochlorothiazide warnings

Fetal toxicity

Telmisartan and hydrochlorothiazide are classified as pregnancy category D medications. Use of medications that act on the renin-angiotensin system during the second and third pregnancy trimesters reduce fetal renal function. These drugs can also increase fetal and neonatal morbidity resulting in death. Other potential neonatal effects associated with these medications include anuria, skull hypoplasia, hypotension renal failure and death. This medication should be discontinued as soon as possible when a pregnancy is detected.

Hypotension in salt or volume depleted patients

Symptomatic hypotension may occur after initialization treatment with telmisartan in patients with an activated renin-angiotensin system (patients on treatment with high doses of diuretics). It is important that volume or salt depletion is corrected in such patients before the onset of telmisartan and hydrochlorothiazide treatment.

Impaired renal function

Changes in renal function, including acute renal failure, can be caused by medications that inhibit the renin-angiotensin system as well as by diuretics. Patients whose renal function depends partly on the activity of the renin-angiotensin system (such as patients with chronic kidney disease, renal artery stenosis, volume depletion or severe congestive heart failure) may be at a higher risk of developing progressive azotemia, oliguria, or acute renal failure when treated with this medication. Renal function should be monitored closely in these patients. The treatment should be withheld or discontinued in patients who develop clinically significant reduction in renal function.

Electrolytes and metabolic disorders

Telmisartan medication can cause hyperkalemia and, especially in patients with diabetes, renal insufficiency. It may raise serum potassium levels when used in combination with other angiotensin receptor blockers.

Hydrochlorothiazide is also known to cause hyponatremia and hypokalemia. Thiazides are known to increase urinary excretion of magnesium, which may result in hypomagnesemia. Hypomagnesemia can result in hypokalemia, which can be difficult to treat even with potassium repletion. It is important that serum electrolytes are monitored closely while on this medication.

Hydrochlorothiazide may decrease urinary calcium excretion, resulting in elevations of serum calcium.

Hydrochlorothiazide may affect the patient's glucose tolerance, resulting in a rise in cholesterol and triglyceride serum levels.

Hyperuricemia may occur in some patients or frank gout may develop in some patients on thiazide treatment. Because telmisartan lowers uric acid levels, its combination with hydrochlorothiazide may attenuate the diuretic-induced hyperuricemia.

Hypersensitivity reaction

Hypersensitivity reaction to hydrochlorothiazide may occur in patients with a history of bronchial asthma and other forms of allergy. Inform your doctor of all allergies you might be having, including food, animals, dyes and even medicines.

Systemic lupus erythematosus

Hydrochlorothiazide has been reported to trigger activation or exacerbation of systemic lupus erythematosus.

Post-sympathectomy patients

The antihypertensive effects of hydrochlorothiazide may be exacerbated in post-sympathectomy patients.

Potassium supplements

Patients are advised not to use potassium supplements or salt substitutes that contain potassium while on telmisartan and hydrochlorothiazide medication without the consent of their healthcare providers.

Acute myopia and secondary angle closure com/health/coma/">glaucoma

Patients should discontinue telmisartan and hydrochlorothiazide treatment and seek medical attention immediately if they develop symptoms of Acute Myopia or Secondary Angle Closure Glaucoma.

As most of the telmisartan is eliminated from the body via biliary excretion, patients with hepatic insufficiency or biliary obstructive disorders can be vulnerable to reduced clearance and higher blood levels.

Patients on hydrochlorothiazide may experience minor alterations of fluid and electrolyte balance. This may develop into hepatic coma in patients with impaired hepatic function or progressive liver disease.

Telmisartan and hydrochlorothiazide storage

The medication should be stored at room temperature (25 degrees C). Tablets should not be removed from blisters unless during administration. Keep all drugs in a cool dry place away from direct sunlight. The medication should be kept out of children's reach. All unused and expired medications should be disposed of appropriately.


Telmisartan and hydrochlorothiazide is a combination medication administered orally to treat hypertension (high blood pressure). Lowering high blood pressure is important for preventing heart attacks, strokes, and kidney problems. The package contains two medicines: telmisartan and hydrochlorothiazide.

Telmisartan belongs to a class of medications called angiotensin receptor blockers (ARBs). It works by disrupting the activity of angiotensin II hormone from activating a receptor in that leads to a rise in blood pressure levels. This way, the medication relaxes the blood vessels to ensure that blood travels throughout the body with ease. Hydrochlorothiazide, on the other hand is a "water pill". It works by increasing the amount of urine the body makes, especially during the onset of the treatment. It also works by relaxing the blood vessels for easy flow of blood.

Telmisartan and hydrochlorothiazide should only be used together when one drug alone fails to lower blood pressure. Your healthcare provider may advise you to start off with one medication first, and then opt for combination if this is the most effective combination for your condition.

As already mentioned, both medications are taken orally with or without food. The drugs should be taken as directed by your healthcare provider, usually once a day. It is advisable that you avoid taking these medications within 4 hours before your bed time to avoid having to get up several times to empty your bladder. The dosage is basically based on the patient's treatment response and medical condition.

Telmisartan and hydrochlorothiazide treatment should be taken regularly to get the most benefit from them. To help you remember, schedule your dose at the same time each day. If it important to continue with medication, while gradually reducing the dosage, even when you feel well.

If you are on cholesterol-lowering medications such as colestipol or cholestyramine, take this telmisartan and hydrochlorothiazide at least 4 hours before or 4 hours after these medications.

Finally, watch out for telmisartan and hydrochlorothiazide side effects and seek medical attention if these side effects are severe or life-threatening.

Last Reviewed:
December 24, 2017
Last Updated:
April 27, 2018
Content Source: