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Health condition

Pernicious anaemia

Pernicious anaemia is an autoimmune condition destroying the stomach's ability to absorb vitamin B12; lifelong B12 injections treat it completely, and awareness of its associations - thyroid disease, gastric changes - completes good care.

Why trust this guide

  • 01

    Editorial team

    Written by our editorial team from the UK sources listed on each page.

  • 02

    Sourced from guidance

    Checked against current NHS and UK specialist society guidance at the time of review.

  • 03

    Current for 2026

    Reviewed on 2026-09-27 with the next review scheduled for 2027-09-27.

Key facts

The essentials at a glance.

The symptoms to recognise, when to seek help, which specialist to see, and what treatment usually involves.

  • Mechanism: autoimmune gastritis eliminates intrinsic factor, the protein essential for B12 absorption - so the deficiency cannot be fixed by diet

  • Symptoms build slowly: fatigue, breathlessness, a sore smooth tongue, pins and needles, unsteadiness, low mood and memory complaints

  • Diagnosis: B12 level, intrinsic factor antibodies (specific but only positive in about half), blood film and clinical picture

  • Specialist: a consultant haematologist; treatment is lifelong hydroxocobalamin injections, and associated autoimmune thyroid disease is worth screening for

Understanding the condition

What it is and what happens next.

What causes it, how it is diagnosed, and the treatment routes available in the UK.

What it is and how it feels

Pernicious anaemia earned its historic name in the era before treatment, when it was uniformly fatal; today it is a manageable autoimmune condition in which the immune system attacks the stomach's parietal cells and their product, intrinsic factor - the escort protein without which dietary B12 passes straight through the gut unabsorbed. Deficiency develops over years as liver stores drain, and its presentation is correspondingly stealthy: fatigue and breathlessness from the anaemia, a characteristically sore beefy tongue, and the neurological creep of tingling feet, subtle unsteadiness in the dark and cognitive dulling that patients often attribute to age or stress - making it a diagnosis that rewards suspicion in unexplained fatigue and neuropathy alike.

Diagnosis and treatment routes

Diagnostic work-up combines the B12 level (interpreted with care, as borderline results are common) with intrinsic factor antibodies - conclusive when positive, but absent in roughly half of true cases - the blood film's oval macrocytes and hypersegmented neutrophils, and response to treatment. Management is simple and lifelong: hydroxocobalamin injections on the standard loading-then-maintenance schedule, with neurological involvement fast-tracking the loading phase; there is no role for stopping injections once the diagnosis is secure. Because autoimmune gastritis raises the long-term risk of gastric neuroendocrine changes and coexists frequently with thyroid autoimmunity and vitiligo, periodic review and a low threshold for thyroid testing round out care - and family members with unexplained fatigue deserve a blood count and B12 check, given the condition's familial clustering. In many parts of the UK, routine NHS referrals for this kind of problem currently take 20-45+ weeks, whereas an initial appointment with a private consultant is typically available within around two weeks.

Seeing a specialist

Who to see, and how quickly you can be seen.

The specialist for this condition is usually a consultant haematologist. Your GP can refer you on the NHS, or you can arrange a private consultation directly.

A quiet reminder

This guide is for information, not medical advice.

Your GP knows your history and can tell you which parts apply to you. If in doubt, see them - and seek urgent care for any of the emergency symptoms described above.

Frequently asked

Common questions about Pernicious anaemia.

Quick, plain-English answers to what people ask us most.

  • What is pernicious anaemia?

    Pernicious anaemia is an autoimmune condition where the body's immune system attacks cells in the stomach needed to absorb vitamin B12, leading to B12 deficiency and, eventually, anaemia and nerve-related symptoms.

  • What causes pernicious anaemia?

    It's caused by autoimmune destruction of stomach cells that produce intrinsic factor, a protein essential for absorbing vitamin B12 from food. Without intrinsic factor, B12 cannot be absorbed even with a normal diet.

  • What are the symptoms?

    Fatigue, pale or slightly yellow skin, breathlessness, pins and needles or numbness in the hands and feet, memory problems, and a sore tongue are common. Symptoms often develop gradually over months.

  • Is pernicious anaemia serious?

    If left untreated, it can cause significant and sometimes irreversible nerve damage alongside worsening anaemia, but with lifelong B12 treatment, most people live entirely normal, healthy lives.

  • Is pernicious anaemia hereditary?

    There is a genetic predisposition, and it can run in families, often alongside other autoimmune conditions such as thyroid disease or vitiligo, though it's not directly inherited in a simple pattern.

  • Can pernicious anaemia be cured?

    It can't be cured, since the underlying autoimmune process persists, but it's very effectively controlled with regular vitamin B12 injections or, in some cases, high-dose oral B12, usually needed for life.

  • How is pernicious anaemia treated?

    Treatment is vitamin B12 replacement, typically by injection initially and then at regular maintenance intervals (often every two to three months) for life, which corrects the deficiency and prevents symptoms returning.

  • How long does it take to feel better after starting treatment?

    Energy levels often improve within a couple of weeks of starting B12 injections, though nerve-related symptoms like numbness can take longer, sometimes several months, to improve, and pre-existing nerve damage may not fully reverse.

  • Pernicious anaemia vs iron-deficiency anaemia — what's the difference?

    Iron-deficiency anaemia is caused by lack of iron, often from blood loss or poor dietary intake, and is treated with iron supplements, while pernicious anaemia is an autoimmune B12 absorption problem treated with B12 injections. Blood tests distinguish clearly between the two.

  • When should I see a doctor, and how quickly can I be seen privately?

    See a doctor if you have persistent fatigue, numbness or tingling, or unexplained pallor, as blood tests can quickly identify B12 deficiency. Private specialist assessment is usually available within about two weeks, faster than typical NHS routine referral waits.