Skip to main content

About hydroxocobalamin - Brand names: Cobalin-H, Neo-Cytamen

Hydroxocobalamin is a manufactured version of the vitamin B12. It's used to treat and prevent vitamin B12 deficiency anaemia, where you have low levels of this vitamin in your body.

Your body requires vitamin B12 to make red blood cells. You can get it from your food or supplements, but sometimes there may not be enough vitamins in what you eat. This can happen if you are vegan or you do not eat much meat or dairy products.

The most common cause of vitamin B12 deficiency in the UK is pernicious anaemia (an autoimmune condition that affects your stomach).

Vitamin B12 deficiency can also be a side effect of metformin, a diabetes medicine, particularly if you take a high dose of metformin or if you take it for a long time.

Hydroxocobalamin is only available on prescription.

It is given as an injection. This will usually be at your GP surgery but you might sometimes have it in hospital.

Key facts

  • Hydroxocobalamin starts to work straight away. However, it may take a few days or weeks before your symptoms start to improve and you feel better.
  • At first, you may need to have the injection a few times a week to boost your levels of vitamin B12. Once your condition improves, you might only have it every few months.
  • Some common side effects are feeling or being sick and diarrhoea.
  • You may have some pain, swelling or itching where you had the injection. This is usually mild and does not last long.
  • It's safe to take for a long time. Some people need to take hydroxocobalamin for the rest of their lives.

Page last reviewed: 13 October 2022
Next review due: 13 October 2025