Losartan is a drug used as a type of antihypertensive medication. Hypertension, or high blood pressure, is a condition which puts a great deal of strain on the heart, and in long-term cases, may cause it and its adjacent organs to malfunction. This results in the blood vessels of various vital organs of the body to be damaged, resulting in possible strokes, kidney damage or even cardiac arrests and heart attacks. In controlled cases of blood pressure, these problems are less probable to manifesting themselves. Losartan is more effective on hypertensive patients who are not suffering from any other cardiovascular conditions.

Losartan causes the blood vessels to relax by preventing the effects of certain substances within the body which can cause the vessels to become strained. Through this effect, blood pressure is lowered.

Usage of losartan in hypertension patients is often encouraged due to the various benefits it has over other medications. Research showed that use of losartan reduces the chances of suffering strokes or developing diabetes. While it does not reduce the chance of a heart attack, it causes significantly less medication-related side-effects than other antihypertensive drugs (such as atenolol) do.