A compound of formula I ##STR1## or a pharmaceutically acceptable salt thereof in which R.sub.1 and R.sub.2 are independently H or methyl (for example N,N-dimethyl-1-[1-(4-chlorophenyl)cyclobutyl]-3-methylbutyl amine hydrochloride optionally in the form of its monohydrate) is used for treating chronic fatigue syndrome.

Um composto do ## do ## STR1 da fórmula I ou de um sal pharmaceutically aceitável disso no que R.sub.1 e R.sub.2 são independentemente H ou methyl (para o hydrochloride do exemplo N, do amine de N-dimethyl-1-[1-(4-chlorophenyl)cyclobutyl]-3-methylbutyl opcionalmente no formulário de seu monohydrate) é usado para o syndrome crônico de tratamento da fatiga.