Acts prominently upon mucous membranes, especially of the mouth and digestive tract, where it causes acute ulcerative stomatitis, the whole mucous surface becoming red and tumid, while in the cheeks, lips, etc., it produces numerous gray-based ulcers. It also acts upon the salivary glands, causing a profuse secretion of acrid saliva. It is thus homoeopathic to aphthae and stomatitis ; follicular ulceration of the mouth and tongue ; follicular pharyngitis ; and has been used successfully, both internally and as a gargle, in the treatment of true diphtheria.