excessive thirst is hard to define. people normally drink varying amounts of liquid depending on their activity level and the temperature indoors and out. there are two main medical conditions that should be considered if you feel constantly thirsty: diabetes mellitus: the common form of diabetes in which high blood sugar levels spill into the urine increasing urine flow. the excessive urination leads to dehydration causing the person to become thirsty and drink more fluid. diabetes insipidus: an uncommon problem in which a hormone called anti-diuretic hormone (adh) is either low absent or not functioning properly. adh normally acts on the kidneys to cause them to retain water. in diabetes insipidus the lack of normal adh function results in high urine flow a constant feeling of thirst and high fluid intake. your doctor can test you for these conditions over one or two office visits.
why am i always thirsty?