An injection device, comprising: a safety shield having a first end and a surface disposed at a second end thereof for contacting a patient's skin, the safety shield having a shield tab extending therefrom; a housing slidably disposed with respect to the safety shield, the housing including a guide groove for engaging the shield tab to guide movement of the housing relative to the safety shield, the guide groove having first and second axial portions (184, 188) and a substantially helical portion connecting the first and second axial portions; a medicament container connected with the housing and having a needle affixed thereto in communication with a medicament disposed within the medicament container, wherein the medicament container is displaceable relative to the safety shield from an initial position to an injection position, to a withdrawn position; a biasing member biasing the medicament container away from the safety shield; and an injector member slidably disposed relative to the medicament container, for expelling the medicament from the medicament container; characterized in that: the housing comprises a cantilevered upper flexible arm and a cantilevered lower flexible arm being locking members of the guide groove, whereby the cantilevered upper flexible arm is disposed on the first axial portion of the guide groove and the cantilevered lower flexible arm is disposed on the second axial portion of the guide groove. a safety shield having a first end and a surface disposed at a second end thereof for contacting a patient's skin, the safety shield having a shield tab extending therefrom; a housing slidably disposed with respect to the safety shield, the housing including a guide groove for engaging the shield tab to guide movement of the housing relative to the safety shield, the guide groove having first and second axial portions (184, 188) and a substantially helical portion connecting the first and second axial portions; a medicament container connected with the housing and having a needle affixed thereto in communication with a medicament disposed within the medicament container, wherein the medicament container is displaceable relative to the safety shield from an initial position to an injection position, to a withdrawn position; a biasing member biasing the medicament container away from the safety shield; and an injector member slidably disposed relative to the medicament container, for expelling the medicament from the medicament container; characterized in that: the housing comprises a cantilevered upper flexible arm and a cantilevered lower flexible arm being locking members of the guide groove, whereby the cantilevered upper flexible arm is disposed on the first axial portion of the guide groove and the cantilevered lower flexible arm is disposed on the second axial portion of the guide groove. the housing comprises a cantilevered upper flexible arm and a cantilevered lower flexible arm being locking members of the guide groove, whereby the cantilevered upper flexible arm is disposed on the first axial portion of the guide groove and the cantilevered lower flexible arm is disposed on the second axial portion of the guide groove.