Hypersensitivity to losartan potassium or to any of the components of Besartan.
Use in pregnancy: Although there is no experience with the use of losartan in pregnant women, animal studies with losartan have demonstrated foetal and neonatal injury and death, the mechanism of which is believed to be its effects on the renin-angiotensin-aldosterone system. In humans, foetal renal perfusion, which is dependent upon the development of the renin-angiotensin-aldosterone system, begins in the 2nd trimester.
When used in pregnancy during the second trimesters, drugs that act directly on the renin-angiotensin-aldosterone system, begins can cause injury and even death in the developing foetus. Losartan is contraindicated in pregnancy, and if pregnancy is detected, losartan should be discontinued immediately.
Use in lactation: It is not known whether Losartan is excreted in human milk. Because of the potential for adverse effects on the nursing infant, a decision should be made whether to discontinue breast-feeding or discontinue the drug, taking into account the importance of the drug to the mother.