A safety needle attachment for a syringe body assembly makes use of a needle holder with a needle fixed in the holder and the holder so constructed that it can, if necessary, be applied to and removed from the syringe body assembly at will. The needle is initially entirely surrounded by a protecting jacket which is releasably interlocked with the holder. When the needle is to be used, the interlock is released and the jacket in effect telescoped over the holder to project the needle through a membrane over the end of the jacket to a working position. After use the jacket is returned to its protecting position and there interlocked in place. Thereafter for those occasions where the attachment is removable from the body assembly, it can be removed for disposal.

A device for limiting the penetration of an injection needle when an injection is administered from an injection apparatus comprises an exterior sleeve (1) arranged around the front part of the injection apparatus (2). In its foremost position, the sleeve (1) surrounds the needle (8) completely, and it may be displaced rearwards while overcoming a spring force (6), to expose the needle (8).

A disposable combination of a hypodermic syringe and needle has a sheath movably mounted on the syringe barrel to normally occupy a first position wherein the sheath extends to cover and protect the needle. Substantially axial guide channels are provided in the exterior surface of the barrel to accept an inwardly pointed boss of the sheath to guide the sheath into a second position and a third position. In the second position of the sheath, relative to the barrel and needle, the needle is at least partially exposed. In the third position of the sheath, which is used for disposal of the syringe and needle combination, the needle is again covered by the sheath and preferably the sheath is irreversibly locked whereby abuse or misuse of the syringe and needle combination is substantially prevented. In alternative embodiments, instead of axial guide channels, the bosses of the sheath may be engaged in appropriately formed circumferential grooves or depressions formed in the outer surface of the barrel.

A needle assembly especially suited for hypodermic syringe use in which an axially collapsible sleeve is positioned over the needle. The sleeve includes an upper axially rigid portion sized to mount over the base portion of the needle, an axially collapsible intermediate portion, and an axially rigid lower portion defining a central bore sized to telescopically receive and protect the lower pointed end of the needle. In use, the sleeve selectively collapses axially as the needle enters the subject so that the point of the needle is never exposed during insertion, and selectively extends axially during withdrawal of the needle so that again the pointed tip of the needle is never exposed.

A safety mechanism for a hypodermic needle comprises a base adapted to be fixed with respect to the needle and a tubular sheath mounted for relative longitudinal movement with respect to the base between a first position for covering the needle and a second position wherein the needle can at least partially protrude from the outer end of the sheath. A latch mechanism cooperative between the base and the sheath is selectively repeatedly shiftable between a latching mode wherein the sheath is latched in its first position, and a free mode wherein the sheath is reciprocable between its first and second positions, the latch including detents for releasably retaining the latch in its free mode.