Aldomet 250mg is a medication used to treat high blood pressure (hypertension). It is also used to treat preeclampsia and eclampsia or hypertensive disorder of pregnancy (HDP), gestational hypertension (GH) or pregnancy-induced hypertension (PIH). Aldomet works by relaxing blood vessels so blood can flow more easily. It lowers blood pressure by decreasing the levels of certain chemicals in your blood.