A microneedle intradermal drug delivery device with auto-disable functionality includes a syringe (12) having a plunger (14) displaceable along a barrel (16) and a microneedle adapter (20) with hollow microneedle(s) (22). The microneedle adapter (20) and the syringe (12) are configured for irreversible engagement such that, after attachment of the microneedle adapter (20) to the syringe (12), the microneedle adapter (20) is resistant to non-destructive manual removal from the syringe (12). Also provided are a self-locking plunger configuration (54, 56, 58) and a sliding safety shield (62).
