Telmisartan

What it is

Telmisartan is an angiotensin II receptor blocker. It blocks the receptor through which angiotensin II constricts blood vessels and drives aldosterone release, so vessels relax and blood pressure falls. It is used for hypertension, and it is prescription-only.

Used for

• Hypertension

What to know while taking it

It can be taken with or without food. Because it reduces aldosterone signalling, it holds potassium back rather than losing it, and that effect adds up with spironolactone, which spares potassium by another route. Ibuprofen and other anti-inflammatory painkillers blunt the blood-pressure effect and put extra strain on the kidneys alongside it. Potassium, creatinine and eGFR are checked for this reason, and the drug is not used in pregnancy because it harms the developing kidneys.

When to see a doctor

Muscle weakness, an irregular or unusually slow heartbeat, or numbness and tingling can point to potassium building up, and much less urine than usual can point to failing kidney function; both mean see a doctor. Pregnancy, or planning one, is a reason to see a doctor promptly rather than continue.

Worth knowing

• Can raise potassium
• Not during pregnancy

Markers to watch

• Potassium
• Creatinine
• eGFR

Nutrients affected

• potassium — raised by (Potassium)