Before you begin using a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use Losartan.

Blood pressure: Occasionally, a larger-than-expected drop in blood pressure occurs after taking losartan, in some cases after the first dose. It is more likely to occur if you take diuretics (water pills), have reduced salt intake, are on dialysis, or are experiencing diarrhea or vomiting. Blood pressure should be checked more often in these situations. If you have Low Blood Pressure or are just starting to take Losartan, you should move slowly when you are rising from a reclining to an upright position to reduce the risk of dizziness.

Dizziness: Losartan may cause dizziness, affecting your ability to drive or operate machinery. Avoid these and other hazardous tasks until you have determined how Losartan affects you.

Kidney problems: The use of losartan may affect the function of the kidneys, especially for those who already have kidney problems. Certain people have experienced changes in kidney function (e.g., people with narrowed blood vessels in their kidneys, or those with severe Congestive Heart Failure). The use of diuretics (water pills), nonsteroidal anti-inflammatory drugs (NSAIDs) or aliskiren may further increase risk of kidney problems for people already at risk for this problem. If you have kidney function problems, your doctor will likely closely monitor your condition while you are taking Losartan.

Liver function: Losartan is removed from the body by the liver. Liver disease or reduced liver function may cause Losartan to build up in the body, causing side effects. If you have liver problems, discuss with your doctor how Losartan may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Losartan, and whether any special monitoring is needed. Your doctor may want to test your liver function regularly with blood tests while you are taking Losartan.

Potassium: Increases in blood levels of potassium can occur with use of Losartan. This rarely causes problems, but your doctor may want to monitor your potassium levels through blood tests.

Pregnancy: Losartan should not be taken by pregnant women as it can cause severe harm or death to an unborn child. If you are planning to become pregnant, discuss alternative medications for blood pressure control with your doctor.

If you become pregnant while taking Losartan, stop taking it and tell your doctor at once.

Breast-feeding: It is not known if losartan passes into breast milk. If you are a breast-feeding mother and are taking Losartan, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using Losartan have not been established for children less than 6 years of age.