diarrhea became very bad; Diarrhea; Weight loss; This is a spontaneous report from a contactable consumer (patient). This report is not related to a study or programme. An 82-years-old female patient received BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE; Solution for injection; Lot Number and Expiration date was not reported), via an unspecified route of administration, administered in Arm Right on 01Mar2021 (at the age of 82-years-old) as DOSE 1, SINGLE for covid-19 immunisation and to prevent coronavirus. BNT162B2 of unknown strength/volume/dose injection to right arm shoulder unknown time in day, morning, might be noon administered at a hospital clinic. Medical history included allergies to weeds and dust in the air but takes like an allergy antihistamine in summertime, so eyes don't itch and high blood pressure from an unknown date and unknown if ongoing. Concomitant medication(s) included amlodipine (AMLODIPINE) taken for high blood pressure from an unspecified start date and ongoing. The patient experienced diarrhea on 02Mar2021, diarrhea became very bad on 23Mar2021, weight loss on Mar2021. Duration of diarrhea was 152 days. The patient underwent lab tests and procedures which included blood test: negative, CAT scan: negative and any test they gave her came back negative on unspecified date. This consumer is the patient who reported Diarrhea and weight loss after being administered Pfizer-BioNTech Covid-19 Vaccine. She called because she lost her CDC vaccine record card and wanted to know how to get that information or another card because eventually, they wanted to travel. Diarrhea initial onset was on 02Mar2021, the day after her first dose of Pfizer-BioNTech Covid-19 Vaccine, at unknown time, might be in the morning. Finally, the last week in Aug2021 she did not have diarrhea any longer. This was after going to the doctor and having many tests done because the doctors had been saying the diarrhea couldn't be a side effect of the Pfizer-BioNTech Covid-19 Vaccine. It was a miserable summer due to the diarrhea and she spent a lot of money going to doctors to decide why this was going on; but any test they gave her came back negative. She experienced weight loss starting in Mar2021 from the Diarrhea because everything she ate went straight through her. Before onset of diarrhea her weight was 120lbs. She is now 114lbs where she had remained persistently since reaching that weight. Regarding treatment and testing they put her on a diet to see if it could help with diarrhea: rice, noodles, chicken, fish, applesauce and tea so that wasn't very fulfilling. She was back to eating regular food and assumes she will gain weight back as she no longer had that problem with the diarrhea. Some days in Mar2021 she just took a book into the bathroom and stayed there for most of the day because the minute she would leave the bathroom she would have diarrhea again. During that time, she took over the counter things to stop the diarrhea and a prescription to stop diarrhea and the diarrhea finally stopped. They took breath test to see if she was allergic to or had trouble with fructose or lactose if that was a cause of it. They did a CAT scan of her stomach area to see if there was anything wrong there. Then they checked to make sure that her gallbladder was ok, she had no problem there. They took blood tests, and it all came back ok. There were no findings on those tests, it was all ok, negative. Clinical outcome of diarrhea was recovered on unspecified date in Aug2021 and weight loss was not recovered.