Hygrine (HYG) and cuscohygrine (CUS) are natural alkaloids of coca leaves but are not found in illicit cocaine seizures. Therefore, they were proposed as markers for coca chewing in contrast to cocaine abuse in urine and hair testing. In order to examine at which step of the illegal cocaine production these compounds are lost, coca leaves were processed according to an authentic procedure by extraction with lime and kerosene, re-extraction with sulphuric acid, and precipitation of coca paste with ammonia. Non-extracted and extracted coca leaves, acidic extract and coca paste were analyzed by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) for cocaine, ecgonine methyl ester (EME), cinnamoylcocaine (CIN), HYG, and CUS. It follows from the results that under these conditions, HYG and CUS are extracted only to a minor extent by kerosene and are not precipitated from the acidic re-extract in the coca paste. Due to this behaviour in illegal cocaine production, they fulfil the conditions as markers for coca chewing in an optimal way. However, for unambiguous discrimination between coca chewing and cocaine abuse in human samples, additional markers of manufactured cocaine are required.