The invention relates to a blood withdrawal device (10) having an active liquid (12) containing a platelet aggregation inhibitor, a microneedle patch (14) having a plurality of microneedles (20), wherein a plurality of microneedles (20) is configured for dispensing the active liquid (12) into the skin (34) of a patient, and comprising a negative pressure generating device (16) connected to a plurality of microneedles (20) such that blood (46) can be drawn from the skin (34) by means of the microneedles (20). According to the invention the active liquid (12) contains a pain killer, the active liquid (12) is arranged in the blood receptacle (18), and the negative pressure generating device (16) is connected to the blood receptacle (18), such that by generating an excess pressure in the blood receptacle (18), the active liquid (12) can be dispensed by way of microneedles (20), and by generating a negative pressure, blood (46) can be drawn into the blood receptacle (18).