had leg cramps; had intensive twitching from her knees to her feet; potential not to take the second shot; she has had an increase in an issue she had previously; This is a spontaneous report received from a contactable reporter(s) (Consumer or other non HCP). The reporter is the patient.  A 53 year-old female patient (not pregnant) received bnt162b2 (BNT162B2), administered in arm right, administration date 13Mar2021 09:30 (Lot number: EN6207) at the age of 53 years as dose 1, single for covid-19 immunisation. Relevant medical history included: "Acute myeloid leukemia", start date: Apr2012 (unspecified if ongoing), notes: In Aug 2012 had stem cell transplant.; "Penicillin allergy" (unspecified if ongoing); "Hyland's leg cramp" (unspecified if ongoing); "Chemotherapy", start date: 2012 (unspecified if ongoing), notes: infusions and total body irradiation; "leg and foot twitching from the knees down" (unspecified if ongoing); "severe leg and foot cramps" (unspecified if ongoing). The patient took concomitant medications.  The following information was reported: MUSCLE SPASMS (non-serious) with onset 13Mar2021 11:30, outcome "not recovered", described as "had leg cramps"; MUSCLE TWITCHING (non-serious) with onset 13Mar2021 11:30, outcome "not recovered", described as "had intensive twitching from her knees to her feet"; CIRCUMSTANCE OR INFORMATION CAPABLE OF LEADING TO MEDICATION ERROR (non-serious) with onset 13Mar2021 11:30, outcome "not recovered", described as "potential not to take the second shot"; CONDITION AGGRAVATED (non-serious) with onset 13Mar2021 11:30, outcome "not recovered", described as "she has had an increase in an issue she had previously". Therapeutic measures were not taken as a result of muscle spasms, muscle twitching, circumstance or information capable of leading to medication error, condition aggravated.  Additional Information: The patient did not have Covid nor tested positive prior vaccination.The patient was not pregnant at the time vaccination. The patient did not receive any other vaccines within 4 weeks prior to the COVID vaccine. A patient received vitamin D3, mag w potassium, Hyland's leg cramp within two weeks of vaccination. In 2012, patient was diagnosed with acute myeloid leukemia & had stem cell transplant. A few months after, patient began having leg and foot twitching from the knees down, often followed by severe leg and foot cramps. It was a sporadic situation that may happen for 2-3 days with a few weeks "rest" in between. Within hours of receiving the first COVID vaccine, the twitching began with great intensity and experienced cramping for several nights in a row. The problem is that the twitching has been almost continuous for 3 weeks, and that is NOT the norm. This includes waking up with the twitching, as well as experiencing it all day long. As a result, patient opted to not get the 2nd vaccination out of fear that this will become chronic and never resolve.The patient stated that since she got the shot three weeks ago that she has had an increase in an issue she had previously. Stated that sometimes nothing triggers it and then sometimes she knows what triggers it. Stated that she deep muscle twitches that started after the shot at all different times of the day. Stated that she is due for her second shot tomorrow and is terrified. Stated that this has not let up since her first shot and she is about to take the second one. Stated that she had pre-existing symptoms prior to the vaccination. A patient wanted to know if anyone else is reporting neurological symptoms.   No follow-up attempts are possible. No further information is expected.