HYDRAGOGUES, amongst physicians, remedies which evacuate a large quantity of water in dropsies. The word is formed from hōs, water, and drōn, to draw or lead; but the application of the term proceeds upon a mistaken supposition that every purgative had some particular humour which it would evacuate, and which could not be evacuated by any other. It is now, however, discovered that all strong purgatives will themselves prove hydragogues, if administered in large quantity, or to persons of weak constitutions. The principal medicines recommended as hydragogues are, the juice of elder, the root of the iris, soldanella, mechoacan, jalap, &c.