experiencing menstrual changes/Menstruation straight for 14 days; This is a spontaneous report received from a contactable reporter(s) (Consumer or other non HCP) from medical information team. The reporter is the patient.  A 43 year-old female patient received bnt162b2 (BNT162B2), administered in arm right (Batch/Lot number: unknown) for 1 day as dose 2, single for covid-19 immunisation. Relevant medical history included: "diagnosed allergies" (unspecified if ongoing); "compromised immune status" (unspecified if ongoing); "respiratory illness" (unspecified if ongoing); "genetic/chromosomal abnormalities" (unspecified if ongoing); "endocrine abnormalities (including diabetes)" (unspecified if ongoing); "endocrine abnormalities (including diabetes)" (unspecified if ongoing); "obesity" (unspecified if ongoing). There were no concomitant medications. Vaccination history included: Bnt162b2 (her first dose on 10Sep), administration date: 10Sep2021, for Covid-19 immunization.  The following information was reported: MENSTRUATION IRREGULAR (non-serious) with onset 17Sep2021, outcome "unknown", described as "experiencing menstrual changes/Menstruation straight for 14 days". Relevant laboratory tests and procedures are available in the appropriate section.  Additional information: Vaccination Facility Type was Clinic. Vaccine was not Administered at private Facility. There was no History of all previous immunization with the Pfizer vaccine considered as suspect (or patient age at first and subsequent immunizations if dates of birth or immunizations are not available). There were no Additional Vaccines Administered on Same Date of the Pfizer Suspect. There was no Prior Vaccinations (within 4 weeks). There was no AE(s) following prior vaccinations. The patient did not have any Family Medical History Relevant to AE(s). Reporter stated that she had seen girls that didn't have issues. Her cousin, she's a nurse and another was a CNA they all had issues. She asked which one they took, but it didn't matter. But all other people they were all good. Her cousin was engaged to a doctor that was the first thing they asked her. She and her brother took Pfizer but she was the only person. Her cousin, but she has underlying conditions, they were all having issues. She didn't know if they took the second dose. Her body was so reactive that the first one, but she didn't ask them if they took the second dose. She continued that everyone else was making up weird stuff, She didn't want to go to the doctor because they would say she might be going through menopause. She was just fine and in one month she got Pfizer and then the next month started menopause. The doctor was going to quench her weird mind again. Her family was full of doctors and they were already giving her all these diagnoses. One month she had Pfizer and then the next month she had menopause. That's abnormal for her, in her 43 years she had never had this happen. Never had anything like this. She would go for 7 days skip maybe 2 then 6 to 7 then she was done, but this was different. Last month she went 14 days straight without a break. the month was long, but in other long months what her body would do was skip a week or 4 days and then next one would come on and not going straight like that and heavy some days. Now she was going to have to get the next shot. No she didn't think so. She didn't do her research before unfortunately, how did she know? These inexperienced people giving this medicine that needed to be done delicately and precisely. She followed up to ask that so what she was experiencing was not considered a serious reaction. She asked that she could give anyone she know this number that experienced this so they could call and not complain, but just reported it and make it known. She had not seen her physician and was thinking about seeing them. She knew she was not crazy. She took the mandated Pfizer vaccine, which she later confirmed was the Pfizer COVID vaccine, on 10Sep2021, and on 17Sep had menstruation and had it 14 days straight and she thought it was a fluke, but all her life, never had it happen and now she was going into the 9th day. She was a little nervous. She was a wreck right now. She was in the bathroom and it was going again. She complained to her aunt. She was not crazy. She was literally shaking. When she went to her physician, she wanted to know what would be the next step. She was really nervous. She said it was a side effect and knew then, but did not know before. Everyone that she knew that took it was fine. Except for one person that had the same thing happened. She did not wish to complete a report for her. Separate report completed for her. Her first cycle after the vaccine went 14 days and then it stopped. Now her new cycle was starting and she had it on Friday. She was already past 7 days and said that was abnormal. The more she questioned it, she thought it was abnormal, because she never had this before. She said the reason she got it is because a collage of reasons. She is got it because of parents, job, etc. AE(s) did not require a visit to Emergency Room and Physician Office.  No follow-up attempts are possible; information about lot/batch number cannot be obtained. No further information is expected.