Bloody stools; Joint pain; This is a spontaneous report received from a contactable consumer (patient). A 32-year-old male (patient) received BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE, lot number FD8448), administered in right side of arm (right arm) on 20Aug2021 (at the age of 32-year-old) as dose 1, single for COVID-19 immunization. Vaccination facility type was reported as pharmacy. Vaccine was not administered at military facility. The patient's medical history included that he had hemorrhoid's (he hadn't had those in 3-4 years and he guesses that might be problematic). The patient's concomitant medications were reported as vitamins. He thought the only thing that came close to it was about 1 month before he started a diet and he was losing weight and lost about 20 pounds of weight and with getting the shot he didn't know if that would adversely affect it. Caller stated he hadn't been taking any medication that would come close to it and he had been avoiding all the medications and he was taking vitamins and that was about it. Patient stated that he had been pretty much clean, no drugs or vaccines within 4 weeks prior vaccinations. Adverse events following prior vaccinations were reported as none before he took this, he double checked allergies in past, so no. History of all previous immunization with the Pfizer vaccine considered as suspect was reported as none. Additional vaccines administered on same date of the Pfizer suspect were reported as none. Patient reported that he had a side effect after the first dose of the vaccine. Caller (patient) was seeking information if he should get the second dose of the vaccine or not following his side effects after the first dose. Caller received his first dose of the PFIZER-BIONTECH COVID-19 VACCINE on Friday 20Aug2021. About 24 hours after (21Aug2021) he experienced bloody stools, he was seeking information if this was a rare or common occurrence. Caller also briefly mentioned he experienced joint pain also. Caller states he had a question about the COVID vaccine and he didn't know as he didn't see it listed. He stated he got the shot on Friday, 20Aug2021 and figured he would wait a couple weeks for other side effects. Caller stated he was wondering, and he was pretty sure he had never had this happen, he had a bloody stool 24 hours after the shot. He stated it was pretty bad and he was wondering if it was that consistent with the vaccine. Caller was asking if it was a side effect and if he should get a second shot. He stated that when he got the shot within 24 hours, he was fine but the next day he had bloody stool. Caller was asking if the vaccine do anything with the blood and if he should get the second shot. He stated he thought he had 1 more week before the second shot. Caller was asking if this was a rare occurrence that happened. Caller stated that on 21Aug2021 in the early morning he had bloody stool and on 22Aug2021 it was improving and on 23Aug2021 he had no bloody stool, it was just bad on 21Aug2021 and for a couple days. Caller stated that his next dose was 10Sep2021. When probed for dose caller stated he had been told about issues from over some other side of the country they gave a whole dose amount. He stated that to him it looked like everything was prefilled and injected and looked correct as much as he knew what was going on. Indication was reported as COVID. To protect his elderly parents experiencing the harsh death of it. He stated that he had heard that it was so close to the SARS that it might actually protect against SARS like the breakout from 5 years ago. About concomitant medications caller stated no, he thought the only thing that comes close to it was about 1 month before he started a diet and he was losing weight and lost about 20 pounds of weight and with getting the shot he didn't know if that would adversely affect it. Caller stated he hadn't been taking any medication that would come close to it and he had been avoiding all the medications and he was taking vitamins and that was about it. He stated his mother reminded him that growing up he had hemorrhoid's but he hadn't had those in 3-4 years and he guesses that might be problematic. The events did not require emergency room or physician office visit. The outcome of the events was resolved on 23Aug2021 for bloody stool and unknown for the other event.  Follow-up (08Sep2021): Follow-up attempts are completed. No further information is expected.