situation is reported as a medication error due to a stand alone Hib being reconstituted by the DTaP-IPV and administered with no adverse event; Initial information received on 02-May-2022 regarding an unsolicited valid non-serious case received from other health professional.  This case involves a 19 month old male patient who had medication error due to a stand-alone hib being reconstituted by the dtap-ipv and administered with no adverse event while receiving vaccine diphtheria/tetanus/5 hybrid ac pertussis/ipv(mrc5)/hib(prp/t) vaccine [Pentacel].  The patient's past medical history, medical treatment(s), vaccination(s) and family history were not provided.  On 02-May-2022, the patient received an unknown dose of suspect diphtheria/tetanus/5 hybrid ac pertussis/ipv(mrc5)/hib(prp/t) vaccine (lot UJ635AA,Expiration Date :2023-01-27 Lot Number:UJ594ABA,Expiration Date :2022-12-18 Lot Number:U7054AA,Expiration Date :2022-12-18 expiry date: unknown) via intramuscular route in the left upper thigh as immunization.  On 02-MAY-2022 the patient developed a non-serious "situation is reported as a medication error due to a stand alone hib being reconstituted by the dtap-ipv and administered with no adverse event (product preparation issue)".  It was reported "The Nurse called regarding PENTACEL. She reconstituted the Hib lyophilized powder with the DTaP-IPV that was in the box, however when she checked the Lot Number of the Hib vial, it did not match the box or her inventory number and also didn't say "Part of Pentacel" as she has normally seen. The PENTACEL was administered to a patient this morning on 2MAY2022. Caller wants to know what to do. 2MAY2022 @ 1221: Caller had patient waiting and asked to be called back with information. 2MAY2022@ 1306pm: Outbound made to original caller (disclaimer given to receptionist and caller). AE and PTC information was gathered from caller. This situation is reported as a medication error due to a stand alone Hib being reconstituted by the DTaP-IPV and administered. Caller states this was a brand new unopened box and doesn't believe anyone switched the Hib portion out of the box for a stand alone vial. Caller states they have other unopened PENTACEL boxes that they will keep an eye out for this issue when opening. She did administer the PENTACEL to a patient. Number of units affected: This is the only they're aware of. They have all new boxes that are unopened. Information to be gathered on the type of needle that was used by the end-user (e.g. gauge size) 25 gauge 1 inch Different lots in same box."  Action taken with DIPHTHERIA, TETANUS, AC PERTUSSIS, IPV AND HIB VACCINE (PENTACEL) was not applicable.  It was not reported if the patient received a corrective treatment for the event (situation is reported as a medication error due to a stand alone Hib being reconstituted by the DTaP-IPV and administered with no adverse event).  At time of reporting, the outcome was Unknown for the event situation is reported as a medication error due to a stand alone hib being reconstituted by the dtap-ipv and administered with no adverse event.  This suspected adverse reaction report is submitted and classified as a medication error solely and exclusively to ensure the marketing authorization holder's compliance with the requirements set out in the Directive 2001/83/EC and Module VI of the Good Pharmacovigilance Practices. The classification as a medical error is in no way intended, nor should it be interpreted or construed as an allegation or claim made by the marketing authorization holder that any third party has contributed to or is to be held liable for the occurrence of this medication error.