Nutritional deficiency is caused by a lack of the vitamin in the diet, whereas acquired deficiency occurs when the intestinal absorption of the vitamin is interfered with by diseases and conditions such as pernicious anemia (an autoimmune disorder affecting intrinsic factor protein produced by gastric parietal cells), chronic atrophic gastritis, Crohn's and celiac diseases, gastric bypass surgery, and medications such as metformin, gastric acid secretion blockers (i.e., proton-pump inhibitors and H2-receptor antagonists), and others (2, 3)

1 = Two B12 2000mcg & Two B-100 Complex Each 10ml B12 2000mcg Contains 10 ml Vitamin B12 2000mcg Each milliliter contains 2000mcg Vitamin B-12 10 Doses of 2000mcg B12 per vial Or 20 half ml doses = 1000mcg each For Intramuscular or subcutaneous injection Date Code: EXPIRES JUN 2027 / MAY 2028 Vegan Friendly Vitamin B12 (cyanocobalamin) GMP Quality is Guaranteed B-100 contains the Vitamins B1 - B2 - B6 - B3 Vitamin B1 (Thiamine) 100mg Vitamin B2 (Riboflavin) 0.5mg B3 Nicotinamide (Active form of B3) 100mg Vitamin B6 (Pyridoxine) 1mg 10ml Vial Contains 10 doses per vial Date Code: Expires FEB 2028 For Intramuscular and Intravenous injection Limit 12 Combos per order 10.00 Flat fee shipping, avg
For others, especially those without proper nutrient balance, it may cause discomfort
I get the Hevert Heweneural 1% (Lidocainhdrochlorid 1 H2O 20mg)
This leads to neurological symptoms
B12 shots work faster than oral sources of B12 and therefore are recommended for individuals who need rapid improvement