a needle stick prevention device (100) for an injection needle carried by a needle support member (101) of a syringe (102) is formed as a one-piece molding and comprises a first part (103) adapted to be attached to the needle support member (101) and a second part (104) providing a needle guard and pivotably movable with respect to the first part to expose the needle for use. the device is adapted to adopt a first position where the needle is protected for transport of the device before use, a second position where the needle is exposed for syringe filling and injection, a third position where the needle is protected after filling but before the injection and a fourth position where the needle is locked in the device following the injection. in one embodiment the guard (104) has a transport recess (124) and a locking recess (125) connected by a locking device (126), the arrangement being such that in the third position the needle (130) is in the recess (124) and is capable of moving to the second position, and in the fourth position the needle moves through the interlocking device (126) to the locking recess (125), with the interlocking device (126) avoiding the move out of the fourth position. The device also includes operative power dissipation protrusions (155) to reduce shield energy (104) as it is returned to the third position and before the interlocking device contacts needle (130) to prevent splash any liquid on the needle (130) outside the device.um dispositivo de prevenção contra picada de agulha (100) para uma agulha de injeção portada por um membro de suporte de agulha (101) de uma seringa (102) é formado como uma moldagem de uma peça e compreende uma primeira parte (103) adaptada para ser fixada ao membro de suporte de agulha (101) e uma segunda parte (104) provendo uma proteção para a agulha e pivotavelmente móvel em relação à primeira parte para expor a agulha para uso. o dispositivo é adaptado para adotar uma primeira posição em que a agulha é proteg
