Warnings

Telmisartan-Hydrochlorothiazid

Medically Reviewed by Dr. Harshi Dhingra, M.D.

Last Reviewed: Mar 25, 2025

Warnings

Telmisartan Hydrochlorothiazide (Micardis HCT) Risks, Warnings, and Complications

Telmisartan hydrochlorothiazide can cause or worsen health problems in some people. Talk to your doctor or pharmacist about taking other blood pressure medicines if you are at a higher risk of adverse reactions from this combination antihypertensive therapy.

FETAL RISK: Telmisartan hydrochlorothiazide and other drugs that act on the renin-angiotensin system can be harmful to an unborn baby if they are used during the second and third trimesters of pregnancy. Use of these medications can lead to oligohydramnios (decreased amniotic fluid volume) and impaired kidney function in the developing fetus. This can lead to congenital abnormalities (birth defects), including skeletal deformities and lung hypoplasia (underdeveloped lungs). In addition, thiazide diuretics can cross the placenta and cause fetal or neonatal jaundice and thrombocytopenia (low platelet count).
Due to the significant fetal risk associated with telmisartan hydrochlorothiazide, this medication should not be taken by pregnant women or women who are breastfeeding an infant.
Tell your doctor if you are pregnant before starting treatment with this combination medicine. Stop taking telmisartan hydrochlorothiazide and call your doctor immediately if you become pregnant while on it.
LOW BLOOD PRESSURE: In people with an activated renin-angiotensin system (for example, those who are salt- or volume-depleted due to high doses of diuretics) can develop hypotension (low blood pressure) after they start taking telmisartan hydrochlorothiazide.
To lower the risk, your doctor will correct volume or salt depletion before starting Micardis HCT. Tell your doctor if you have diarrhea, vomiting, or excessive sweating, which can lead to dehydration and low blood pressure. Call your doctor if you develop severe dizziness or lightheadedness while on this drug.
RENAL IMPAIRMENT: Taking diuretics or renin-angiotensin system inhibitors can lead to changes in kidney function, including acute kidney failure. Risk factors include certain medical conditions, such as volume depletion, chronic kidney disease, renal artery stenosis, or severe congestive heart failure. There is an increased incidence of acute renal failure on this combination of blood pressure medicine in people with these conditions.
Tell your doctor if you have a history of kidney problems. Call your doctor without delay if you develop decreased urination or dark yellow urine while on this medicine. Your doctor will monitor renal function periodically during treatment with serum creatinine and other tests. If you develop signs of significantly compromised renal function, your doctor may recommend temporarily withholding or discontinuing therapy with telmisartan hydrochlorothiazide.
ELECTROLYTE DISTURBANCES AND METABOLIC DISORDERS: Telmisartan and other drugs that inhibit the renin-angiotensin system can cause hyperkalemia (high serum potassium levels). This risk is especially high in people with renal insufficiency (kidney disease), diabetes mellitus, or those taking other angiotensin receptor II blockers (ARBs), angiotensin converting enzyme (ACE) inhibitors, or other drugs that can raise plasma levels of potassium.
Hydrochlorothiazide, on the other hand, can cause hypokalemia (low potassium plasma concentration) and hyponatremia (low sodium plasma concentration). Thiazides can also increase urinary excretion of magnesium, resulting in hypomagnesemia (low magnesium). Hypomagnesemia can lead to hypokalemia (low serum potassium), which can be difficult to manage.
Hydrochlorothiazide also decreases urinary calcium excretion, which can lead to hypercalcemia (increased serum calcium levels). In addition, hydrochlorothiazide can cause metabolic changes, including changes in glucose tolerance and increased blood cholesterol and triglyceride levels.
Some patients can develop hyperuricemia (high uric acid levels) and frank gout while on a thiazide diuretic such as hydrochlorothiazide. However, telmisartan decreases uric acid and cancels this effect.
Your doctor will monitor plasma concentrations of electrolytes periodically while you are on telmisartan hydrochlorothiazide.
ALLERGIC REACTION: Serious hypersensitivity reactions can occur in patients taking telmisartan hydrochlorothiazide. The risk of this happening is higher in people with a history of bronchial asthma. Seek emergency medical care if you develop difficulty breathing while on this medicine.
ACUTE MYOPIA AND SECONDARY ANGLE-CLOSURE GLAUCOMA: Sulfonamide drugs like hydrochlorothiazide can cause an unusual reaction resulting in acute transient myopia (short sightedness) and acute angle-closure glaucoma (increased intraocular pressure which can cause permanent vision loss if not treated).
Tell your doctor if you have a sulfonamide or penicillin allergy, as this can put you at an increased risk of these serious eye problems. Stop taking telmisartan hydrochlorothiazide and seek emergency medical care if you develop vision problems, including decreased vision, eye pain, swelling, or redness.
SYSTEMIC LUPUS ERYTHEMATOSUS: Thiazide diuretics, including hydrochlorothiazide, can activate or worsen lupus (systemic lupus erythematosus or SLE). Before starting diuretic therapy, tell your doctor if you have a history of lupus.
POST SYMPATHECTOMY PATIENTS: The antihypertensive effect of thiazide diuretics like hydrochlorothiazide can be enhanced in people who have undergone sympathectomy (a surgical procedure done to cut the sympathetic nerve chain that runs down the back, in order to treat conditions such as excessive sweating, Raynaud phenomenon, or chronic pain).

Precautions Before Starting Telmisartan Hydrochlorothiazide

Tell your doctor if you have ever had allergic reactions to telmisartan, hydrochlorothiazide, any of the active or inactive ingredients in telmisartan hydrochlorothiazide tablets, other angiotensin II receptor antagonists, other diuretics, or any other medications. Your pharmacy can give you a list of ingredients.

Give your doctor and pharmacist a complete list of your medications, including prescription medications, over-the-counter medicines, vitamins, supplements, and herbal products. This will lower the potential risk of interactions between your medications.

Give your healthcare professional a complete medical history. Telmisartan hydrochlorothiazide may not be safe for people with certain medical conditions such as heart failure, bile duct blockage, kidney disease, liver disease, diabetes mellitus, high cholesterol, asthma, gout, lupus (SLE), or glaucoma.

Tell your doctor if you are pregnant, could be pregnant, plan to get pregnant, or are nursing an infant with breast milk. Do not breastfeed while on this medicine.

Precautions During Use of Telmisartan Hydrochlorothiazide (Micardis HCT)

Keep all your medical and lab appointments while on this medication. Your healthcare provider will do blood tests to check kidney function and electrolyte levels periodically.

Keep a log of your blood pressure readings at home and bring it to your healthcare appointments. Your doctor may adjust the dose of telmisartan hydrochlorothiazide based on your response to the medicine.

Take telmisartan hydrochlorothiazide at least 1 hour before or 4 hours after cholesterol-lowering medications such as colestipol and cholestyramine. Also, take it 3-4 hours before bedtime because hydrochlorothiazide is a diuretic (water pill) and can make you urinate more. Taking it later in the day can lead to nighttime awakenings to urinate.

Many patients experience dizziness, lightheadedness, drowsiness, and blurred vision on telmisartan hydrochlorothiazide. Do not drive, operate machinery, or do any other hazardous activity until you know how it affects you. Avoid drinking alcohol because alcohol can make these side effects worse.

Taking telmisartan hydrochlorothiazide can cause orthostatic hypotension (dizziness, lightheadedness, and fainting due to low blood pressure) when going from a sitting or lying position to standing. Get out of bed slowly to avoid falls. This is more likely to happen when you first start treatment and after a dose adjustment.

Drink plenty of water and stay well hydrated during treatment with telmisartan hydrochlorothiazide. Call your doctor if you develop vomiting, diarrhea, excessive sweating, or are unable to drink enough fluids (this can lead to dehydration and a drop in blood pressure). Tell your doctor if you develop dizziness, weakness, or low blood pressure.

Hydrochlorothiazide can make your skin more sensitive to sunlight and increase the risk of non-melanoma skin cancer. Avoid unnecessary sun exposure and wear sunscreen, sunglasses, and protective clothing when outdoors. Tell your doctor without delay if you notice any new skin growths.

Telmisartan hydrochlorothiazide can cause changes in glucose tolerance. If you have diabetes and take medication to control blood sugar levels, talk to your provider about how often you should monitor blood glucose and whether you need to adjust the doses of your diabetes medication.

Do not stop taking telmisartan hydrochlorothiazide without talking to your doctor, even if you are symptom-free and your blood pressure is controlled. This medicine only works as long as you continue taking it. Stopping treatment suddenly can lead to dangerously high blood pressure and increase your risk of heart attack and stroke.

Telmisartan hydrochlorothiazide can cause serious harm to an unborn baby. Talk to your doctor about using adequate birth control while on this medicine. Tell your doctor immediately if you become pregnant while on this drug.

Tell all your healthcare providers you are on telmisartan hydrochlorothiazide before any surgery or medical tests, including dental procedures.

Telmisartan Hydrochlorothiazide (Micardis HCT) Drug Interactions

Certain other drugs can affect how telmisartan hydrochlorothiazide works. Possible interactions with other medicines can increase the risk of severe adverse reactions. Your doctor may change the dose of your medicine, switch you to a different medicine, and/or monitor you carefully for side effects if there are known interactions between Micardis HCT and your other medicines.

If you have diabetes mellitus, you should not take a blood pressure medication called aliskiren (Tekturna, Tekturna HCT, Tekamlo, in Amturnide) at the same time as telmisartan hydrochlorothiazide.

The following medications can have interactions with telmisartan hydrochlorothiazide:

Other angiotensin receptor II blockers
Angiotensin-converting enzyme (ACE) inhibitors
Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs)
Digoxin
Lithium
Skeletal muscle relaxants
Barbiturates
Narcotics
Pressor amines (norepinephrine)
Diabetes medications
Cholesterol lowering drugs such as colestipol and cholestyramine
Potassium supplements and potassium containing salt substitutes

The above list may not describe all the potential interactions of telmisartan hydrochlorothiazide. Give your doctor or pharmacist a complete list of your medications, including prescription drugs, nonprescription drugs, dietary supplements, and herbal remedies. Also, tell your healthcare professional if you smoke, drink alcohol, or use recreational drugs because some of these substances can cause serious health complications when used with prescription medications.

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