Telmisartan

Key facts

• Telmisartan (the ingredient in Micardis) is an angiotensin II receptor blocker (ARB) that relaxes blood vessels so blood pressure falls.
• You take it once daily, with or without food; it can take a few weeks to show its full effect.
• Do not take telmisartan if you are pregnant. ARBs can seriously injure or kill a developing baby, especially in the second and third trimester.
• Seek urgent care for swelling of the face, lips, tongue or throat, or for muscle weakness and an irregular heartbeat, which can signal a dangerously high potassium level.

What telmisartan treats

Telmisartan treats hypertension (high blood pressure), alone or combined with other blood-pressure medicines. It is also used in adults at high risk of heart attack or stroke who cannot take an ACE inhibitor, to lower that cardiovascular risk. It does not treat kidney disease directly, but by controlling blood pressure it helps protect the kidneys in people with diabetes.

How telmisartan works

A hormone called angiotensin II narrows blood vessels and raises blood pressure. Telmisartan blocks the receptor that angiotensin II acts on, so vessels stay relaxed and pressure falls. This also reduces the workload on the heart and eases pressure inside the kidneys' filtering units.

Before you take it

• Do not take telmisartan during pregnancy; stop it as soon as pregnancy is confirmed and use effective contraception while taking it.
• Tell your prescriber about kidney or liver disease, heart failure, or if you take potassium supplements, potassium-sparing diuretics, or regular NSAIDs, since these raise the risk of high potassium and kidney strain.
• Avoid combining telmisartan with an ACE inhibitor or with aliskiren, particularly if you have diabetes or kidney impairment.
• Blood tests to check kidney function and potassium are usually done before you start and periodically afterward.

Side effects

Common effects include dizziness, back pain, sinus congestion, diarrhea, and tiredness.

Stop and seek urgent medical care for any of these:

• Swelling of the face, lips, tongue, or throat.
• Fainting or a severe drop in blood pressure.
• Muscle weakness or an irregular heartbeat from high potassium.
• Reduced urination or swelling in the ankles.

Safety essentials

• Pregnancy is contraindicated: telmisartan can cause fetal injury or death, particularly if taken in the second or third trimester. Tell your prescriber immediately if you become pregnant so treatment can be switched.
• Blood pressure can fall sharply after the first few doses in people who are dehydrated or already on a diuretic; rise slowly from sitting or lying down.
• Routine blood tests monitor kidney function and potassium, especially if you have diabetes, kidney disease, or take other medicines that act on the same hormone system.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.