Patient Information Leaflet

Vitamin B12 injections

Vitamin B12 injections

If you are considering having a Vitamin B12 treatment, we recommend that you read the following information. This will help you to be fully prepared and know what questions to ask. Vitamin B12 injections are a Prescription Only Medication (POM), and your initial consultation should be performed face to face with a prescribing practitioner registered with a professional body. You should be offered a cooling off period to allow you time to consider the treatment and make an informed decision whether to proceed.

What are Vitamins?

Vitamins are essential micronutrients required in trace quantities for normal growth and development and to ensure normal body functioning. Essential nutrients cannot be synthesised by the body in sufficient quantities and must be taken in via a healthy diet. Their impact on the body’s health is critical and deficiencies of these micronutrients can have severe and even life-threatening effects on the body.


Vitamins are generally classified into 2 categories:


Water Soluble: These vitamins are soluble in water and some of these are not easily stored within the body, requiring a constant source from the diet. They include Vitamin C (Ascorbic acid), Thiamin (B1), Riboflavin (B2), Niacin (B3), Pantothenic acid (B5), Pyridoxine (B6), Biotin (B7), Folic acid (B9) and Cobalamin (B12).


Fat Soluble: They are absorbed within the body and transported in a manner like fats and are stored within the body’s fatty tissue and the liver. These vitamins include A, D, E and K.


When booking an appointment, ensure your initial consultation will be with a prescribing practitioner.
What is Vitamin B12 and what does it do?

Vitamin B12 is one of the water-soluble vitamins and available as an intramuscular injectable medication called hydroxocobalamin. Vitamin B12 is required to help your body to use fat and carbohydrate for energy and it also helps to make protein and DNA. It is an essential vitamin to help maintain blood, nerve cells, and neurological function. Vitamin B12 is only found naturally in animal products and dietary sources include liver, fish, meat, eggs, dairy products, yeast extract (such as marmite) and foods that have been fortified with B12. Although there are different medications of Vitamin B12, the World Health Organisation recommends the use of hydroxocobalamin as it remains in the body longer than other formulations, which means less treatments over time. Injected B12 begins to work immediately, but it can take days or weeks to feel the benefit.


Brain Function: Low levels of Vitamin B12 have been linked to decline in brain function and recent evidence suggests there is also a link with dementia. However, there is no evidence to suggest brain function can be improved in people with normal Vitamin B12 levels.


Osteoporosis (Brittle bones): There is a link between low levels of B12 and reduced bone mass, increasing the risk of fractures.


Depression: It has been suggested that low levels of Vitamin B12 is associated with depression and long-term treatment with B12 may reduce recurrence and severity of depression.


Energy, weight loss and mood: There is actually little or no evidence to suggest that treating people with normal B12 levels with Vitamin B12 injections will improve wellbeing, energy levels, weight or mood.

What causes Vitamin B12 deficiency?

Vitamin B12 deficiency is relatively common, and the main causes of deficiency include:


  • Pernicious anaemia (a medical condition where your own immune system attacks healthy cells in the stomach, preventing the absorption of Vitamin B12)
  • Vegan and Vegetarian diets
  • Episodes of extreme dieting or a poor diet over a long time
  • People taking certain medications, including metformin, anti-convulsants, and antacids
  • Previous bowel surgery or medical conditions affecting the bowel
  • Increasing age
  • Risk factors also includes smoking and alcohol excess
How does the body absorb and store Vitamin B12?

The absorption of Vitamin B12 from the diet begins within the mouth, where proteins within the saliva attach to the vitamin to prevent it from being destroyed by the acid in the stomach. Specialised cells (parietal cells) within the stomach produces a substance called intrinsic factor, which binds to Vitamin B12 enabling it to be absorbed within the small intestines. Once it enters the blood stream, it can be reabsorbed along with bile to be stored for a long time in the liver (60%) or within muscle (30%) until it is required. Anything that interferes with this process can lead to low levels of Vitamin B12 within the body.


Not all people will require Vitamin B12 injections, even if their levels are low, as oral supplements are available which can improve levels over time.

Do I need Vitamin B12 injections?

Below is a list of some of the signs and symptoms of low B12. If you feel that you have these symptoms, then you must initially seek medical advice from your General Practitioner. It is likely that you will have a blood test which should include checking your level of Vitamin B12. If it is below recommended levels, you will likely have a series of injections at your GP practice to correct this.


Symptoms and signs of Vitamin B12 deficiency:


  • Extreme tiredness
  • Lethargy
  • Feeling faint
  • Parasthesia (pins and needles)
  • Sore tongue
  • Mouth ulcers
  • Muscle weakness
  • Visual disturbances
  • Mobility problems
  • Confusion
  • Poor memory
  • Lack of judgement
  • Depression
Is it painful?

Vitamin B12 is injected using a fine needle, usually into the muscle at the top of the arm. As with any injection, it can sting and cause a slight burning sensation when it is administered. It can also cause some discomfort and throbbing in the area for a few hours or days afterwards.


If the injection is very painful, you should inform your treating practitioner.

Is it safe?

All treatments and medications have a risk associated with them and all risks and possible side-effects should be fully disclosed to you during your consultation before you agree to any treatment. Millions of treatments have been carried out worldwide and when Vitamin B12 has been sourced from a reputable pharmacy and administered by a medically qualified healthcare practitioner, the risks are very low.


You should not have B12 injections if:


  • You have an allergy to hydroxocobalamin or any of its ingredients.
  • You have low potassium levels or medication that may reduce your potassium.
  • You have other deficiencies, including folic acid or iron.
  • You have a blood disorder.
We do not recommend that treatments are performed in a non-clinical environment.

Generally, side-effects are uncommon, often mild, and usually resolve within a few days of treatment. You may experience some pain, itching, redness or swelling at the injection site. This will usually settle quite quickly without any intervention, however, if you experience any prolonged side-effects, it is important to contact your practitioner for a review. Bruising is uncommon, but if it does occur, it may take up to 2 weeks to fully resolve.


Possible side-effects include:


  • Injection site pain
  • Bleeding and/or bruising at the injection site
  • Redness, itching, irritation at the injection site
  • Nausea and vomiting
  • Diarrhoea
  • Headaches
  • Dizziness
  • Hot flushes

If vomiting and diarrhoea are more severe, this can affect the oral contraceptive pill and additional precautions will be required.


Rarely, adverse effects can be serious and include:


  • Serious palpitations due to low potassium levels
  • Anaphylaxis (serious and life-threatening allergy)

Signs and symptoms of a serious allergy may include a rash, wheezing, difficulty in breathing, tight chest or throat, trouble speaking and swelling of the mouth, face, lips, tongue and/or throat. If you experience any of these, you must ring 999 immediately.


If you develop any unexpected side-effect after treatment, it is important to contact your practitioner as soon as possible, who may be able to offer advice or corrective treatment.


What does the procedure involve?

Prior to treatment, you should complete a medical history with your practitioner, you should also receive all the relevant information you need to make an informed decision about whether to go ahead with treatment or not, as well as possible side-effects specific to your treatment and costs involved. It is usual to have an initial consultation and then rebook treatment for a later date, giving you the opportunity to have a cooling off period to consider all the information provided.


Do not feel pressurised or coerced into having treatment at the same time as your consultation.

Before treatment, you should be given the opportunity to have any further questions answered and sign a consent form, either printed or electronically produced. The practitioner will examine the treatment area to determine the most appropriate injection sites and dosage required for optimum results.


The area for injection will most likely be at the top of your arm into the muscle, it is usual to use the non-dominant arm. The area will be inspected to find the best place for injection. Some practitioners may disinfect the skin prior to injection, but this is not a requirement. The skin will be gentle pinched prior to treatment and the actual injection can cause a stinging or burning sensation that can vary in intensity. Some people find that it is quite painful, whereas most just experience a mild stinging. The actual injection will last for a few seconds only.


Following the procedure, your skin may be cleaned again, or gentle pressure applied if there had been some bleeding at the site. You will be asked to remain for 15 minutes after your injection to allow time for you to recover and for the practitioner to ensure that you do not have a reaction to the injection. If you are due to have a series of injections, you will then be able to schedule your next appointment. For maintenance, Vitamin B12 injections may be administered every 6 to 12 weeks. Your practitioner will record the batch number, expiry, and site of injection on your treatment record and will provide you with appropriate verbal and/or written aftercare.


If you have never previously had a Vitamin B12 injection, it is important to allow 15 minutes for observation.
Am I suitable for treatment?

Most people are suitable for Vitamin B12 injections, although it is recommended that you have your B12, folate, iron and potassium levels checked prior to commencing treatment. If you have very low levels of B12, this should be investigated further by your General Practitioner.


You may not be suitable for treatment if any of the following apply:


  • If you are under the age of 18 years.
  • If you are pregnant or breast-feeding.
  • Previous allergy to hydroxocobalamin.
  • If you have kidney problems or previously low potassium levels.
  • If you have other deficiencies such as folic acid or iron.
  • If you have any blood disorders.
  • If you have a severe needle phobia.
It is important to be honest about your medical history, and any medication taken, so that you can have a safe and effective treatment.
Pre-treatment advice
  • Avoid taking anti-inflammatories (such as aspirin, ibuprofen, naproxen) for 3 days prior to treatment (unless this has been prescribed by your doctor) as this increases the risk of bruising.
  • Alcohol, fish oils, St. John’s Wort, Gingko Biloba, garlic and Vitamin E should also be avoided for 3 days prior to treatment to lessen the risk of bruising.
  • If you are unwell on the day of your appointment, contact the practitioner to reschedule.
  • Ensure your practitioner is informed if there are any changes in your medical history or medication taken before receiving any treatment.
Post-treatment advice

After treatment, most people can resume their normal daily activities. Immediately after treatment, there may be some discomfort, redness, and minor swelling at the injection site, which should settle in time. If you develop any bruising, which may be apparent at the time of treatment, it is usually minor and settles within a few days. Occasionally, more significant bruising can occur. Rarely, you may develop a headache after treatment which can last a few days. Simple analgesia can be taken for this if needed.


Many practitioners advise the following:


  • Try to avoid touching or rubbing the area of injection.
  • Avoid heavy exercise and over-use of the injected muscle for 24 hours.
  • If you develop any diarrhoea, ensure you maintain good hydration by increasing fluid intake.
  • Contact your practitioner if you experience any unwanted side-effects.
Choosing your practitioner

Ensure you know the following information:


  • Practitioner’s full name
  • Practitioner’s profession
  • Practitioner’s contact details (address, telephone number, and email)
  • An emergency contact number in case a complication occurs.

Practitioners should be registered with a professional body (General Medical Council, General Dental Council, Nursing and Midwifery Council, General Pharmaceutical Council or Health and Care Professions Council) and you can check their current registration status online. Practitioners are accountable to these bodies and are legally required to have indemnity insurance in place for all the treatments they perform.


If you are not happy with your treatment outcome, you should attempt to resolve this with your treating practitioner in the first instance. If you need to see a different practitioner, you are entitled to receive a copy of your treatment record. However, the benefits of Vitamin B12 treatments are subjective, and you may or may not notice any changes in your overall health and wellbeing.

The ACE Group World patient leaflets have been produced to give you some ideas of what the treatment involves, possible side effects, what you should expect and what you should ask.

Patient Leaflets

Purchase Patient Information Leaflets to use in your own practice.

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