For the vast majority of people taking B12 at standard supplemental doses, this isn't a concern
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The following are the most consistently reported signs: Sudden, sharp tightening in a specific muscle group (back, neck, leg, shoulder, calf, hand, or forearm) Muscle twitching or visible rippling beneath the skin a phenomenon called fasciculationsespecially in the abdomen, thighs, or eyelids A hard, knotted area in the muscle that is tender to the touch (often called trigger points or muscle knots) Reduced range of motion after a spasm, coupled with muscle stiffness lasting hours or days Burning or aching pain radiating from the spasm site common in cervical spasms and lumbar back spasms Nocturnal cramping waking from sleep due to leg cramps at night, charley horses, or toe cramps Stomach twitching or quivering in the abdomen, particularly with dehydration or electrolyte imbalance Root Causes of Persistent Muscle Cramps & Spasms Understanding what causes chronic muscle spasms is the most important step toward effective treatment
What syringe size should I use for B12 injections
The ideal time to get B12 shots to lose weight is in the morning or early afternoon
The amount of vitamin B12 you may need each day will vary depending on your age