Demeclocycline hydrochloride is primarily used as an antibiotic to treat bacterial infections, particularly those caused by susceptible strains of bacteria. It is effective against a variety of infections, including respiratory tract infections, urinary tract infections, and skin infections. Additionally, it is used in the management of acne due to its ability to reduce inflammation and bacterial growth.

Beyond its antibiotic properties, demeclocycline hydrochloride is also utilized in the treatment of Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH). It works by inducing a form of nephrogenic diabetes insipidus, which helps to correct the fluid imbalance associated with SIADH. This application makes it a valuable therapeutic option in endocrinology and nephrology.

The compound is typically administered orally, and its use requires careful monitoring to avoid potential side effects such as photosensitivity, gastrointestinal disturbances, and renal toxicity. It is important to follow prescribed dosages and consult healthcare professionals for appropriate treatment plans.