I was told by a number of nurses that i must have a script to get a b12 injection. why is this and is it true?

It depends: Vitamin B12 is an essential vitamin which is critical in formation of blood in the human body. So if you are Anemic, you should get blood tests done to find the cause. B12 is sometimes the cause for anemia...many times it is due to Iron deficiency. Either way you need to get your CBC done to check your hemoglobin(Hb level) and see a physician who can guide you in treating your anemia(if needed).

Sublingual B12: Agree with Dr. Lehga. If you must, you may take sublingual B12 that may obviate the need for prescription and injection. It would be prudent to discuss any and all medications you take with your doctor. Wish you good health! - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Drink enough water daily, so that your urine is mostly colorless. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex, if you have sex.