Generic Hyzaar medication should not be used if you are allergic to hydrochlorothiazide or losartan, or if you are not able to urinate. Do not use this medication without telling your local doctor if you are pregnant. Losartan may lead to injury and even death to the unborn child if taken during the second and third trimesters of pregnancy. Before you buy Hyzaar online, tell your local doctor if you have congestive heart failure, kidney or liver disease, asthma, low or high blood levels of potassium, gout, lupus, diabetes, or an allergy to sulfa drugs. Follow your local doctor's directions about the type and quantity of liquids you should drink. In some instances, drinking too much liquid can be as unsafe as not drinking plenty. In rare occasions, this drug can cause a condition that results in the breakdown of skeletal muscle tissue, leading to kidney failure.