Disclosed is a medical injection device (1) comprising a needle assembly (20) having a cannula (21) and a telescopic shield (30) for covering the distal tip (23) in a no use situation. The telescopic shield further carries a cleaning reservoir (40) for cleaning the needle cannula between two subsequent injections. The cleaning reservoir is provided with an opening (43) connecting to an overflow reservoir (51/55) such that the cleaning liquid contained in the cleaning reservoir can retract and expand upon temperature changes and does not enter the needle lumen instead. In one example, the overflow reservoir is formed as a channel (51).