she is experiencing copious liquid diarrhea/severe diarrhea.; horrible one-sided headache back to her ear.; This is a spontaneous report from a contactable other hcp (Nurse). A 66-year-old female patient received BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE, solution for injection, Batch/Lot Number: EW0181; Expiration Date: 31Aug2021), dose 1 via an unspecified route of administration, administered in Deltoid Left (upper) on 19Jul2021 as dose 1, single for covid-19 immunisation; hydrocodone (HYDROCODONE), via an unspecified route of administration from an unspecified date (Batch/Lot number was not reported) to an unspecified date, at 10 mg for headache; atropine sulfate, diphenoxylate hydrochloride (DIPHENOXYLATE/ATROPINE), via an unspecified route of administration from an unspecified date (Batch/Lot number was not reported) to an unspecified date, at 2.5-0.025 (unspecified units) for diarrhoea; sumatriptan (SUMATRIPTAN), via an unspecified route of administration from an unspecified date (Batch/Lot number was not reported) to an unspecified date, at 100 mg for headache; ibuprofen (MOTRIN MIGRAINE) tablets, via an unspecified route of administration from an unspecified date (Batch/Lot number was not reported) to an unspecified date, at 200 mg for headache. Medical history included migraine from an unknown date and unknown if ongoing She does get migraines occasionally like 2 times a year. She gets about 2 mg a year, she has Sumatriptan and took under Reporter direction a 100 mg of that each migraine, incontinence from an unknown date and unknown if ongoing, irritable bowel syndrome with diarrhea from an unknown date and unknown if ongoing. The patient previously took xifaxan for diarrhoea, dexamethasone since February 2021 for treatment of respiratory illness. And in order to allow her to get the vaccine, her doctor and pulmonologist decided to halve her dose of dexamethasone. If that went ok for 2 weeks, she could get vaccine. The patient has a ton of medical conditions. Concomitant medication: she must be on almost 20 medications (unspecified). The patient did not receive any other vaccine prior to 4 weeks of vaccination. The patient reported that, two days after the first dose, 17 hours later or 70 hours later (not specified clearly), she woke up in night with horrible one-sided headache that went back to her ear. She does get migraines occasionally like 2 times a year. The patient reports this was different. It happened again yesterday (24Jul2021) and this morning (25Jul2021), total it happened 3 times since the vaccine. The Reporter wants to check in and know that headaches can be a side effect. But the big deal is that patient is experiencing copious liquid diarrhea that just started today (25Jul2021) well in the night yeah, well early in the morning today, like 3 in the morning. I can't tell to treat and whether to treat her diarrhea, whether it's maybe the vaccine or her issues coming up again. And the Reporter just doesn't know with the diarrhea, what is going on and how to treat it. The patient is now saying she will not take second dose of vaccine, for which Reporter don't blame her. She is pretty miserable from the side effects, if they are side effects. The headaches probably are. The Reporter has no clue about the digestive stuff. The patient works 2 jobs seven days a week and, in the evenings, and she can't take time off for severe diarrhea. The Reporter doesn't know what program to start the patient on for the diarrhea. She is on Medicare. The medicine she mentioned that was the only thing that really helped her costs an arm and a leg. And she wanted to know is there any information on supplement or vitamin usage to use concomitantly with vaccine to make it work better and it was informed to Reporter that Pfizer does not have that information as Pfizer does not provide treatment recommendations for patients. In addition, Pfizer does not recommend the use of the Pfizer BioNTech Covid-19 Vaccine in any manner other than as described in the regulatory authority. Deferred to HCP. The patient received treatment for headache, 10 mg of Hydrocodone repeated once so it was 10/325 and 200 mg Motrin and the same for the, the total of 2 or 3 for the headaches and Motrin 4 tablets of 200mg. She gets about 2 mg a year, she has Sumatriptan, and she took under Reporter direction a 100 mg of that each migraine, for each headache. The Reporter doesn't think for migraine and they never really go away, they get better, they get a lot, 80%, 75% better but they never really go away. And for the diarrhea the patient took Diphenoxylate Atropine, which is normal, 2.5-0.025. The patient was taking a lot not that Reporter told her to take this much. She was taking 4 tablets at once and 3 times a day, well is taking. Yeah, because it's happening. And the Reporter was not sure if she's been taking even more (reporter was not sure) because she has, messed the bed, she messed her clothes, it just comes out. The outcome of events was unknown.; Sender's Comments: Based on the available information in the case, the causal association between the event diarrhoea and the suspect drug BNT162B2 cannot be excluded. The case will be reassessed once new information is available.  The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to regulatory authorities, Ethics Committees, and Investigators, as appropriate.