Vitamin B12 Deficiency and Injections:

What is Vitamin B12 and Why It Is So Vital?

Vitamin B12, or cobalamin, is an essential water-soluble vitamin vital for producing healthy red blood cells and maintaining a healthy nervous system. While the body stores B12 in the liver for up to four years, a deficiency can cause a wide range of symptoms that worsen over time if left untreated.   

A deficiency can cause general symptoms related to anaemia, such as extreme fatigue, lack of energy, and breathlessness. It can also lead to more serious neurological problems, which, if left untreated, may become permanent. These neurological symptoms can include pins and needles, numbness, muscle weakness and impaired physical coordination.

Why Vitamin B12 Is So Important

Vitamin B12 (cobalamin) is essential for: Healthy red blood cell production, Proper nerve function, DNA synthesis and overall energy.

The body stores B12 in the liver for several years, but when levels drop, symptoms can appear, including:

• Fatigue and weakness

• Shortness of breath

• Neurological signs: pins and needles, numbness, memory problems

• Severe cases: balance issues, muscle weakness, and even irreversible nerve damage if untreated

  
  

What Causes Vitamin B12 Deficiency?

While a poor diet can contribute, most cases in the UK are due to absorption issues, not intake. Common causes include: Pernicious anaemia – an autoimmune condition that destroys intrinsic factor, a protein needed for B12 absorption; Digestive disorders – Crohn’s disease, coeliac disease; GI surgery – gastric bypass or gastrectomy; Medications – long-term use of PPIs or metformin; Strict vegan or vegetarian diets – B12 is found naturally only in animal products.

Why Are Injections the Standard Treatment?

If absorption is the problem, oral tablets won’t work effectively. Intramuscular hydroxocobalamin injections deliver B12 directly into the bloodstream, bypassing the gut.

They are the gold standard for:

• Pernicious anaemia

• GI surgery patients

• Severe or symptomatic deficiencies

• Cases where oral absorption is unreliable

  
  

What’s the Typical Injection Schedule in the UK?

According to NHS and BNF guidelines:

Loading Phase (to restore B12 stores):

• 1mg hydroxocobalamin intramuscularly three times a week for 2 weeks

• If there are neurological symptoms: every other day until improvement

Maintenance Phase:

• 1mg intramuscularly every 2–3 months for life in most cases

• Neurological involvement: often every 2 months

Your clinician will individualise this based on your condition and symptoms.

Can High-Dose Oral B12 Work Instead?

Yes—for many patients. Clinical studies show that high-dose oral B12 (1,000–2,000 µg/day) can be as effective as injections for: Dietary causes (e.g., vegan diet), Mild deficiencies, Patients who prefer tablets and have intact absorption.

However, if you have pernicious anaemia or permanent absorption issues, injections remain essential.

Are Injections for Life?

It depends on the cause:

• Permanent issues (e.g., intrinsic factor loss) → lifelong treatment

• Diet-related deficiency → may switch to oral therapy once levels normalise

  
  

Safety, Monitoring & Practical Points

• Hydroxocobalamin injections are safe and well tolerated

• Common side effect: mild pain at the injection site

• Blood tests and symptoms will be checked after treatment begins

• Some patients need flexible dosing if symptoms return before the next injection

Injections vs Oral Supplements: A Quick Comparison

Aspect	Injections	Oral Tablets
Efficacy	Excellent	Excellent (if absorption intact)
Convenience	Every 2–3 months	Daily dosing
Best For	Pernicious anaemia, malabsorption	Diet-related deficiency
Cost	Higher	Lower

Prognosis: Can You Recover Fully?

With early diagnosis and consistent treatment, prognosis is excellent.

• Fatigue and anaemia symptoms often improve quickly

• Neurological symptoms may take longer—and severe nerve damage can be permanent if untreated

• With lifelong management, most patients live completely normal, symptom-free lives

Busting the Myths

Myth: B12 injections boost energy in everyone Fact: They only help if you are deficient

Myth: B12 injections aid weight loss Fact: No scientific evidence supports this claim

Key Takeaways

✔ B12 is vital for blood, nerve health, and energy✔ Deficiency is often caused by absorption issues—not just diet✔ Injections are the UK gold standard, especially for pernicious anaemia✔ Oral B12 works well for diet-related cases or if absorption is intact✔ Treatment may be lifelong for many patients

Have Questions?

If you think you have symptoms of B12 deficiency or need treatment advice, Book an injection at Pulteney Pharmacy for £39.99 or contact us for more information https://www.pulteneypharmacy.com/booking-calendar/vitamin-b12-injection?category=f3fc4ba1-a1fd-4634-9e8a-2795594fd21d&referral=service_list_widget

References

• NHS – Vitamin B12 or folate deficiency anaemia

• NHS Inform – Vitamin B12 Deficiency

• British National Formulary (BNF) – Hydroxocobalamin dosing

• NICE Guidelines – Vitamin B12 Deficiency

• Cochrane Library – Oral vs IM B12 studies

• PubMed Central – High-dose oral B12 trials