GUILLAIN BARRE SYNDROME; LOST ABOUT 12 LBS; DIARRHOEA; SORE ARM; This spontaneous report received from a patient concerned a 63 year old White and non Hispanic or Latino female. The patient's weight was 149 pounds, and height was 64 inches. The patient's past medical history included: vertigo (rarely), and concurrent conditions included: hypertension, non alcoholic, smoker, and smokes marijuana, and other pre-existing medical conditions included: The patient was otherwise healthy. The patient experienced dry cough when treated with lisinopril.  The patient received covid-19 vaccine ad26.cov2.s (suspension for injection, route of admin not reported, batch number: 1808986, expiry: UNKNOWN) dose was not reported, 1 total, administered on 27-JUL-2021 to left arm for prophylactic vaccination. Concomitant medications included diazepam, losartan potassium, and valaciclovir hydrochloride.  On 27-JUL-2021, right after vaccination, the patient experienced a bit of sore arm, which lasted a couple of days. The patient could not remember exact date for rest of report, but it was started possibly around on 15-AUG-2021 or 16-AUG-2021. The patient's feet started feeling strange, like pins and needles, and she was in a lot of pain. The patient had diarrhea three times. She went to the chiropractor because her back was bothering her. The patient could not endure the pain (started in the feet, then to legs, then to hips, and to upper back), so they went to Emergency room (ER) in the middle of the night. The ER gave her some pain medication (unspecified) and she left (not admitted). It was reported that two days later she was back in the ER, and was admitted for 9 days. In the hospital, she was diagnosed with Guillain barre syndrome (GBS). Advil did not help the pain at all. It was reported that the patient needed to move more slowly and was still in pain. The patient was going to see primary care physician (PCP) tomorrow for follow-up. There was no expiration date on vaccination card. The patient had lost about 12 lbs in the hospital. She did not have access to any of the hospital reports. The patient was admitted on 15-AUG-2021 or 16-AUG-2021 and was discharged on 25-AUG-2021. The patient had a nephrologist, neurologist; perform Magnetic resonance imaging (MRI), spinal taps, Computerized tomography (CT scan) scans. Laboratory data included: CT scan (NR: not provided) Not reported, MRI (NR: not provided) Not reported, and Spinal tap (NR: not provided) Not reported. Treatment medications included: ibuprofen. The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The patient recovered from sore arm on JUL-2021, had not recovered from Guillain barre syndrome, and the outcome of lost about 12 lbs and diarrhoea was not reported. This report was serious (Hospitalization Caused / Prolonged).; Sender's Comments: V0: 20210858474- COVID-19 VACCINE AD26.COV2.S- Lost about 12 lbs  This event is considered unassessable. The event has a compatible/suggestive temporal relationship, is unlabeled, and has unknown scientific plausibility. There is no information on any other factors potentially associated with the event. 20210858474-COVID-19 VACCINE AD26.COV2.S -Guillain Barre Syndrome. This event is labeled per RSI and is therefore considered potentially related