Carbocisteine is an active pharmaceutical ingredient that is commonly used to treat respiratory diseases such as chronic obstructive pulmonary disease (COPD) and bronchitis. Although carbocisteine is a widely recognized term in medical circles, there are several synonyms that can be used interchangeably. These include carbocysteine, carbocysteine lysine salt, S-carboxymethylcysteine, and SCMC. The various synonyms of carbocisteine are often used in the manufacturing and formulation of pharmaceuticals and are also used by healthcare professionals in prescribing medications. Using these synonyms helps to ensure that patients receive the correct medication and dosage to manage their respiratory diseases.