A syringe assembly (2) comprises a syringe barrel (4) comprising an inner chamber (14) filled or adapted to be filled with medicament, and a channel (18) in fluid communication with the chamber and through which medicament is dispensed. The assembly further comprises an outer sheath (6) configured to be removably attached to the syringe barrel, and comprising a projection (40) which is received by the channel when the outer sheath is attached to the barrel, thereby creating a seal, which prevents medicament from flowing therethrough.