Istisu (Hot Water) in Masalli in the south of Azerbaijan– Isti su – is one of the therapeutic water of Azerbaijan. It is situated at 13 km distance form Masalli city, on the bank of Vilash river.

This water contains hydrogen sulphite, sodium chlorite, magnesium, hydrocarbonate and 30 milligrams of iodine in 1 litre. This water is extracted from 90-250 km depth of the earth at temperature more than 60 degrees.

The following diseases can be treated with this water: rheumatism and its complications (arthritis, polyarthritis, joint pains, arthrosis); skin diseases (psariosis, dermatitis, neurodermatitis, fungus, eczema); diseases of kidney and urinary tract (pielitis, uretritis, pielonefritis, pielocystitis); radiculitis; prostate; hypertension; diseases of liver and bile duct; female diseases (metritis, endometritis, erosion of the neck of uterus, herbicide, colpitis); female and male childlessness; gastrointestinal diseases (gastritis, esofogitis, colitis, intestinal defecation); traumatic injuries.

The healing power of Istisu was even confirmed by 12 scientists coming from the Soviet Union in the 1960s.