Worst GI pain/Two days were at constant pain levels of 9 to 10. The rest of the first eight days were pretty much around 8; Vomited once; I was also nauseated; Diarrhea/ alternating diarrhea; alternating diarrhea and constipation.; Cramps; This is a spontaneous report received from contactable reporter(s) (Consumer or other non HCP). The reporter is the patient.  A 65 year-old female patient (not pregnant) received bnt162b2 (BNT162B2), administered in arm right, administration date 30Mar2021 15:00 (Batch/Lot number: unknown) at the age of 65 years as dose 1, single for covid-19 immunisation. Relevant medical history included: "Histamine intolerance" (unspecified if ongoing); "Multiple chemical sensitivity" (unspecified if ongoing); "Environmental illness" (unspecified if ongoing); "Asthma" (unspecified if ongoing); "Hypothyroidism" (unspecified if ongoing); "IBS" (unspecified if ongoing); "Interstitial cystitis" (unspecified if ongoing); "Known allergies yes, many" (unspecified if ongoing), notes: Known allergies: Yes, many. Concomitant medication(s) included: LEVOTHYROXINE; VENTOLIN [SALBUTAMOL]; KETOTIFEN; CALCITRIOL. The following information was reported: GASTROINTESTINAL PAIN (non-serious) with onset 30Mar2021 21:00, outcome "recovering", described as "Worst GI pain/Two days were at constant pain levels of 9 to 10. The rest of the first eight days were pretty much around 8"; VOMITING (non-serious) with onset 30Mar2021 21:00, outcome "recovering", described as "Vomited once"; NAUSEA (non-serious) with onset 30Mar2021 21:00, outcome "recovering", described as "I was also nauseated"; DIARRHOEA (non-serious) with onset 30Mar2021 21:00, outcome "recovering", described as "Diarrhea/ alternating diarrhea"; GASTROINTESTINAL MOTILITY DISORDER (non-serious) with onset 30Mar2021 21:00, outcome "recovering", described as "alternating diarrhea and constipation."; MUSCLE SPASMS (non-serious) with onset 30Mar2021 21:00, outcome "recovering", described as "Cramps". Therapeutic measures were not taken as a result of gastrointestinal pain, vomiting, diarrhoea, gastrointestinal motility disorder. Therapeutic measures were taken as a result of nausea, muscle spasms.  Additional Information: Reason for Lot unknown reported, Not available/provided to reporter at the time of report Completion. the most recent COVID-19 vaccine was administered in Hospital (facility). Patient did not receive any other vaccines within 4 weeks prior to the COVID vaccine. patient received other medications within 2 weeks of vaccination: Levothyroxine, Ventolin, Ketotifen PO, Calcitriol. Adverse Event reported as, Patient got the 1st dose of the Pfizer vaccine on 30 March and endured over a week of the worst GI pain I have ever experienced. Two days were at constant pain levels of 9 to 10. The rest of the first eight days were pretty much around 8. It's gradually getting better. I was also nauseated, vomited once, had diarrhea, then alternating diarrhea and constipation. Things still aren't back to my not very good normal. I tried 25mg PO diphenhydramine for nausea and cramps when things were at their worst. I was able to manage a couple of hours of sleep per dose along with 3mg melatonin. The relief was minimal or maybe it was just the sedation, but it enough to enable me to sleep. Prior to vaccination, patient wasn't diagnosed with COVID-19. Since the vaccination, patient had not been tested for COVID-19. Vaccine Facility information available. Ethnicity information is available. Race information is available.  No follow-up attempts are possible. No further information is expected.