The invention relates to a method for obtaining pure tetrahydrocannabinol from reaction mixtures containing tetrahydrocannabinol compounds or from raw products containing tetrahydrocannabinol compounds. According to said method, the tetrahydrocannabinol compounds in the reaction mixture or in the raw product are converted into crystallisable derivatives, preferably using a suitable solvent, said derivatives are then crystallised and isolated, and the pure tetrahydrocannabinol compounds are then obtained from the crystallised derivatives. The invention also related to the use of compounds produced in this way for the production of a medicament for human therapy, and to the medicaments thus produced.