Known brand names include Cozaar.
An angiotensin receptor blocker (ARB) that relaxes blood vessels to lower blood pressure. It treats high blood pressure, lowers stroke risk in hypertension with a thickened left ventricle, and slows kidney damage from diabetes.
Losartan blocks the receptor that angiotensin II, a hormone that tightens blood vessels, attaches to in blood vessel walls and the adrenal glands. The body turns part of it into an active form that blocks the same receptor even more strongly. With angiotensin II shut out, blood vessels relax and the adrenal glands release less aldosterone. It does not block the enzyme that breaks down bradykinin, so it does not boost bradykinin the way ACE inhibitors do.
Blood pressure starts to fall within the first week, and the full effect can take 3 to 6 weeks. It has little effect on heart rate, and blood pressure has not rebounded when it was stopped suddenly. In people whose blood pressure or kidneys lean on this hormone system, such as those low on fluid or salt, it can cause low blood pressure or a drop in kidney function. Blocking this system during pregnancy can harm or kill an unborn baby.
Losartan is a pill that lowers high blood pressure, which left untreated can damage the brain, heart, blood vessels, and kidneys. Lowering blood pressure cuts the risk of strokes and heart attacks. In people with high blood pressure and left ventricular hypertrophy, an enlargement of the walls on the left side of the heart, it lowers the risk of stroke. In people with type 2 diabetes and high blood pressure who already have kidney damage, it slows the kidney disease from getting worse.
It is used by adults and by children 6 years and older with high blood pressure, alone or with other blood pressure medicines. It controls high blood pressure but does not cure it. There is evidence that its stroke benefit does not apply to Black patients.
Dizziness, cold-like symptoms, a stuffy nose, back pain, and lightheadedness when standing up are the common complaints. The label treats high potassium, a drop in kidney function, and rare swelling of the face, lips, tongue, or throat as serious. It also warns that it can harm or kill an unborn baby, so it is not used in pregnancy.
A clinician may order these while someone is taking it.
This is the boxed warning, the warning the FDA label prints first.
Fetal toxicity. Drugs acting on the renin-angiotensin system can injure or kill the developing fetus. Stop losartan as soon as pregnancy is detected.
Sources: [1]