hyperthyroidism; Tachycardia/Increased heart Rate; fainted; Sweaty; Clammy; Dehydrated; extremely fatigue; Nausea; Bad Headache; This spontaneous case was reported by a pharmacist (subsequently medically confirmed) and describes the occurrence of HYPERTHYROIDISM (hyperthyroidism), TACHYCARDIA (Tachycardia/Increased heart Rate) and SYNCOPE (fainted) in a 46-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 032821A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     The patient's past medical history included Syncope in March 2020 and COVID-19 virus test positive on 16-Feb-2021. Concomitant products included MAGNESIUM OXIDE, ASPIRIN [ACETYLSALICYLIC ACID], UBIDECARENONE (COQ 10) and COLLAGEN for an unknown indication.    On 09-Apr-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 10-Apr-2021, the patient experienced HYPERTHYROIDISM (hyperthyroidism) (seriousness criterion medically significant), TACHYCARDIA (Tachycardia/Increased heart Rate) (seriousness criterion medically significant), SYNCOPE (fainted) (seriousness criterion medically significant), HYPERHIDROSIS (Sweaty), COLD SWEAT (Clammy), DEHYDRATION (Dehydrated), FATIGUE (extremely fatigue), NAUSEA (Nausea) and HEADACHE (Bad Headache). At the time of the report, HYPERTHYROIDISM (hyperthyroidism), TACHYCARDIA (Tachycardia/Increased heart Rate), SYNCOPE (fainted), HYPERHIDROSIS (Sweaty), COLD SWEAT (Clammy), DEHYDRATION (Dehydrated), FATIGUE (extremely fatigue), NAUSEA (Nausea) and HEADACHE (Bad Headache) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 10-Apr-2021, Blood pressure measurement: 120/80 mmhg (normal) 120/80. On 10-Apr-2021, Heart rate: 108 bpm (High) 108 bpm. On an unknown date, Blood pressure measurement: 110/60 mmhg (Low) 110/60. On an unknown date, Blood thyroid stimulating hormone: elevated (High) Elevated. On an unknown date, Electrocardiogram: normal (normal) normal.     The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown) was unknown.   For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter did not provide any causality assessments.   On an unknown date, T3 and T4 investigations were done; however, results were pending.   Treatment medication included Tylenol.  This case concerns a 46-year-old female with serious unexpected events of hyperthyroidism, tachycardia, syncope, and nonserious unexpected hyperhidrosis, cold sweat, dehydration, and nonserious expected fatigue, nausea, headache. Latency 2 days after first dose mRNA-1273. Event outcomes unknown. Based on current available information and temporal association between the use of the product and the start date of the event, a causal relationship cannot be excluded.; Sender's Comments: This case concerns a 46-year-old female with serious unexpected events of hyperthyroidism, tachycardia, syncope, and nonserious unexpected hyperhidrosis, cold sweat, dehydration, and nonserious expected fatigue, nausea, headache. Latency 2 days after first dose mRNA-1273. Event outcomes unknown. Based on current available information and temporal association between the use of the product and the start date of the event, a causal relationship cannot be excluded.