Mercurius cyanatus

Malignant diphtheria with intense redness of fauces and great difficulty of swallowing; pseudo-membranous formation extends all over fauces and down throat; putrid, gangrenous diphtheria, with phagedenic ulceration; membranous croup. Great weakness; extreme prostration; cannot stand up from weakness. When it corresponds to the genus epidemicus, like every other remedy, is effective as a prophylactic.