Methods for treating psychiatric and psychological diseases or conditions, including depression, by use of L-tryptophan or a derivative or analog thereof and a derivative of phyllokinin are described. The methods can be used together with other agents for treatment of depression or other psychiatric or psychological diseases or conditions. Pharmaceutical compositions comprising at least one of L-tryptophan or a derivative or analog thereof and a derivative of phyllokinin together with a pharmaceutically acceptable excipient are also described. The pharmaceutical compositions can include other therapeutically active agents for the treatment of psychiatric or psychological diseases or conditions such as depression.
