Pyrovalerone is a psychostimulant. It has a central action. Pyrovalerone inhibits the dopamine transporter and the norepinephrine transporter, and is a weak inhibitor of the serotonin transporter. Pyrovalerone was demonstrated to reduce symptoms of chronic fatigue in humans. It stimulated locomotor activity in mice. Though pyrovalerone is still occasionally prescribed, it is used infrequently due to problems with abuse and dependence. Side effects of pyrovalerone include anxiety, fragmented sleep or insomnia and trembling, shaking or muscle tremors.