dizzy; fell down multiple times; headache off and on; lost his balance; just turn around and head started spinning; low blood sugar (40); sore arm; This is a spontaneous report from a contactable consumer (patient) received via Pfizer. A 67-year-old male patient received the second dose of BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE, lot number EL9266 (it looked like 9266 or 9244)) via an unspecified route of administration in the left arm on 18Feb2021 at a single dose for COVID-19 immunisation. Medical history included stroke, balance was always off because of stroke, congestive heart failure, high blood pressure, atrial fibrillation, depression, diabetic (has diabetes), liver, enlarged heart, and cholesterol. Concomitant medication(s) included warfarin for an unspecified indication; entecavir for liver; metoprolol for high blood pressure and congestive heart failure; losartan for stroke and enlarged heart; bupropion for depression; glipizide for diabetes; metformin for diabetes; diltiazem hydrochloride (DILT-XR) for blood pressure and reduces stroke; atorvastatin for cholesterol. The patient had his second dose of the Pfizer Covid-19 vaccine on 18Feb2021 and wanted to know these side effects. He had a sore arm on Feb2021 that was fine and went away on 2021. The following Sunday on 21Feb2021, he had really low blood sugar (40). He never had it this low (blood sugar never got that low like 40). He had to call emergency and went into emergency. He also had to call reported the week afterwards on 2021, his blood sugar was still low. In the following week, his blood sugar still stayed relatively low, not as low as when he went into emergency but it was still low between 50 and 70 in 2021 (also reported that the blood sugar was low the following week, the whole week, his blood sugar was still low, lower than it normally was). After that week, he started getting out of nowhere he just turn around and head started spinning on Mar2021, he was dizzy on 04Mar2021 and he lost his balance (couldn't tell because his balance was always off because he had stroke so he couldn't tell if it's from prior stroke or the vaccine) like he kept falling down and every time he got up he kept falling down (fell down multiple times) on Mar2021 (also reported that then after the week that's when he started getting really dizzy and falling down)- that just kept happening. He also had a couple of incidents of vertigo but, he usually fall down and got up and it usually go away but this one he kept falling down. He made it to his bed and he was going to call, but he was just resting. After that (now), he had been having off and on headaches on Mar2021. He wanted to know if anyone else has reported this and how long would this last. He talked to 3 of his doctors and these side effects of the vaccination. After the question they said, they really couldn't tell, as it can be understood that it could be a mixture of his health conditions and all his medications that he takes, cause these things happened he was just trying to find out if there was any different test, what caused his blood sugar go down. They stopped his medication that had brought back up. The falling down and headaches, they were not sure, so he was calling. Other people had called them up, the doctors really couldn't tell. They didn't really know. He didn't blame them. It was hard to tell, everybody was different, so he was just trying calling to find out. He was still experiencing headache on and off and dizziness. The HCP took him off his diabetic medications. He hadn't taken anything for the headache. He did take a couple of pills for the dizziness when he fell down because might thought it was of vertigo, so they gave him this medication- already taken 2 of them which was meclizine 25mg and took it twice. He had a CAT SCAN (CSCAN) on 09Mar2021 and MRI on 14Mar2021, both with unknown results. The outcome of the event 'sore arm' was recovered in 2021 as it already went away; 'low blood sugar (40)', 'dizzy', 'headache off and on', 'lost his balance' was not recovered; of the rest of events was unknown.