alternating constipation; cramps and alternating constipation and diarrhea.; nausea; cramps and alternating constipation and diarrhea.; intestinal distress/stomach distress; Aggravated intestinal problems; His legs were wobbly; 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 85 year-old male patient received bnt162b2 (BNT162B2), intramuscular, administered in arm left, administration date 09Mar2021 14:15 (Lot number: EN6206) at the age of 85 years as dose 1, single for covid-19 immunisation. Relevant medical history included: "IBS" (unspecified if ongoing). Concomitant medication(s) included: PERCOCET [OXYCODONE HYDROCHLORIDE;PARACETAMOL]. The following information was reported: ABDOMINAL DISCOMFORT (non-serious), outcome "unknown", described as "intestinal distress/stomach distress"; IRRITABLE BOWEL SYNDROME (non-serious) with onset 13Mar2021, outcome "not recovered", described as "Aggravated intestinal problems"; CONSTIPATION (non-serious), outcome "unknown", described as "alternating constipation"; DIARRHOEA (non-serious), MUSCLE SPASMS (non-serious), outcome "unknown" and all described as "cramps and alternating constipation and diarrhea."; NAUSEA (non-serious), outcome "unknown", described as "nausea"; GAIT DISTURBANCE (non-serious) with onset 13Mar2021, outcome "unknown", described as "His legs were wobbly".  Additional information: Patient states he has received both of his doses of the Pfizer BioNTech COVID-19 vaccine and has been experiencing nausea and things like that and what he calls intestinal distress or stomach distress. He tells that he had a history of irritable bowel syndrome but reports that what he was experiencing was worse than usual. He states he was "feeling pretty good" after the first dose but then reports that it started about 3 to 4 days after his first dose of the vaccine and has continued to last, even after getting his second dose. Patient would like to know if the "intestinal distress was something reported by others after receiving the vaccine. He was concerned about how long this may last because it has already been going on for a while now.Patient has had two shots. The 1st shot was 3 weeks ago and he had no normal things like fever, chills. He has intestinal problems anyway and this aggravated his condition such as nausea, cramps and alternating constipation and diarrhea. With the intestinal problems, normally, he would have good days and bad days. After this, he has not had any good days really. It has aggravated it. That went on and he had second shot a couple of days ago. He had no fever, but did have a tiny bit of chills. This was nothing compared to what his wife had the day after. He is still having the intestinal problems. His other people in his family, 2 to 3 people have gotten intestinal problems with nausea. He would like to know if Pfizer has had reports of anyone else experiencing these symptoms. It took 3-4 days after second dose before he had symptoms. He was feeling good. It has not let up until now. There was no prescriber. It took a while to get on the list to get it. He had first dose on 09 Mar 2021. He still has some intestinal distress with some nausea and cramps. They have been pretty steady since the 13Mar2021 His legs were wobbly but he was able to walk. He is unable to confirm if they were given in the muscle, but thinks it was because it was 2-3 inches down from his shoulder. He has not felt any pain in his arm. He noticed one thing that is different. Usually, he has IBS, and if he takes a small Percocet, it helps a lot. Since he had the vaccine, the Percocet, which he later stated showed on the bottle as Oxycodone,Acetaminophen 5,325, does not work as well as it used to. Sometimes it would clear it up immediately. It is not working anywhere near what is used to be. He has taken 7to 8 out of this bottle. He only takes one at a time. It usually doesn't work too well for the second one. Usually it is just once a day. Before this, he was taking maybe 1 every 7 days, and now is taking 1 every 2-3 days. It is in a pharmacy vial with no lot or expiration. Count size was 60. He would be willing to send a sample. There was no seal as it is in a pharmacy vial. With the 2nd vaccine he provided additional writing on the vaccine card of PFE-BNT. Vaccine supplemental form.Vaccination facility type was Hospital. History of all previous immunization with the Pfizer vaccine considered as suspect). Additional Vaccines Administered on Same Date of the Pfizer Suspect was none Aggravated intentional problem - early morning. NO ER or physician's office required Prior Vaccinations (within 4 weeks) was frist Pfizer COVID vaccine. AE following prior vaccinations was none Medical history including but not limited to these conditions: diagnosed allergies, compromised immune status, respiratory illness, genetic chromosomal abnormalities, endocrine abnormalities (including diabetes) and obesity was none. Family medical history was none.  No follow-up attempts are possible. No further information is expected.