Causticum is a potassium compound that is unique to homeopathy. It was manufactured and proved by Hahnemann in the early 19th century; he noted that it caused an astringent sensation and burning taste on the back of the tongue.
This remedy is mainly used for weakness or paralysis of the nerves and muscles in the bladder, larynx, vocal cords, upper eyelids, or the right side of the face. In the bladder, this can lead to bedwetting, especially if the person is very cold, and leakage of urine when sneezing, coughing, walking, or blowing the nose. Hoarseness and laryngitis are often associated with a dry, deep cough where it is difficult to bring up mucus. Raw, burning pain is characteristic, especially in rheumatism, and in heartburn in pregnancy.
Prepared chemically by distilling freshly burned lime, potassium bisulfate, and water.
Causticum is a fascinating constitutional type. It is quite uncommon, and the Causticum personality has been described in only a sketchy fashion in the old materia medicas. Consequently, many homeopaths have only a vague impression of the Causticum mentality.