Abstract: The invention relates to a method for the quick and direct on-site detection of drugs and drug substitutes which are in solid form. According to the invention, the drugs or drugs substitutes are transferred to a decomposition vessel or reaction vessel without being pretreated, especially without being reduced in size. Afterwards, they are mixed with a solvent or a solvent mixture containing at least one organic solvent. In addition, the suspension and/or solvent containing the drugs or drugs substitutes is/are directly subjected to a known drug test method, especially using drug test strips. The invention also provides a solvent or solvent mixture and a decomposition solution therefor, and a device for carrying out the method.