Mercurial diuretics, although previously widely used, have largely been superseded by safer diuretics such as thiazides, and are hardly used anymore. Inorganic mercury compounds, such as mercury(I)chloride (calomel), were found to have diuretic properties several centuries ago, when they were used to treat syphilis. However, inorganic mercury compounds are very toxic and also have a strong laxative effect. Organic mercurials were found later, which were much more potent as diuretics and safer to use than inorganic ones. Mercurial diuretics cause diuresis by reducing the reabsorption sodium in the ascending loop of Henle, thus causing more water being delivered to the distal convoluted tubule. In the long run, mercurial diuretics tend to accumulate in the liver and the kidneys, causing damage.
Some common organic mercurials: