Health condition
Factor XI deficiency
Factor XI deficiency causes an unpredictable, usually mild bleeding tendency, most evident after surgery on tissues with high clot-dissolving activity such as the mouth, nose and urinary tract; it is common in people of Ashkenazi Jewish ancestry.
Why trust this guide
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Editorial team
Written by our editorial team from the UK sources listed on each page.
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Sourced from guidance
Checked against current NHS and UK specialist society guidance at the time of review.
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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.
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Bleeding correlates poorly with factor level - some with low levels never bleed
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Risk concentrates around surgery in the mouth, nose, throat and urological sites
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Tranexamic acid alone covers many procedures safely
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Plasma or factor concentrate is reserved for higher-risk surgery, used cautiously
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
Factor XI reinforces clots rather than initiating them, which explains the disorder’s odd personality: spontaneous bleeds are rare, joints are spared, and trouble surfaces mainly where clots face strong natural dissolving activity - dental extractions, tonsillectomy, prostate and nasal surgery - or with heavy periods and after childbirth. Even within one family, bleeding tendency varies widely.
Diagnosis and treatment routes
Planning beats prediction. A careful bleeding history and procedure-specific risk assessment decide cover: tranexamic acid suffices for many operations, while major or high-risk surgery may justify factor XI concentrate or plasma, tempered by a recognised thrombosis risk with concentrates in older patients. An anaesthetic and obstetric plan noting the deficiency prevents most difficulties before they arise. In many parts of the UK, routine NHS referrals for this kind of problem can take months, 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 Factor XI deficiency.
Quick, plain-English answers to what people ask us most.
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What is factor XI deficiency?
Factor XI deficiency is a diagnosis used by clinicians to describe a specific pattern of symptoms or findings. It's usually confirmed after a proper assessment, since several conditions can look similar at first.
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Why does factor XI deficiency happen?
The exact cause of factor XI deficiency can involve a mix of genetic, environmental and lifestyle factors, and it isn't always possible to pin down a single trigger. A specialist assessment can help identify any modifiable risk factors relevant to you.
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How would I know if I have factor XI deficiency?
Symptoms of factor XI deficiency vary from person to person and can range from mild and easily missed to significant enough to affect daily life. Because overlapping conditions can produce similar symptoms, a clinical assessment is the most reliable way to confirm what's actually going on.
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Is factor XI deficiency serious or dangerous?
Most cases of factor XI deficiency are manageable with appropriate care, though, like many conditions, it can occasionally lead to complications if left unassessed or untreated. Your clinician can give you a realistic sense of the risks based on your specific presentation.
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Does factor XI deficiency run in families?
Many forms of factor XI deficiency have a genetic or inherited component, and some are linked to specific gene changes that can run in families. If there's a family history, genetic counselling can help clarify the pattern of inheritance and whether relatives might benefit from testing.
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Can factor XI deficiency be treated or prevented?
Factor XI deficiency can often be managed effectively, and in some cases prevented or reversed, with the right combination of lifestyle changes, medication or other targeted treatment. A specialist will tailor the approach to your circumstances rather than applying a one-size-fits-all plan.
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What treatment options are available for factor XI deficiency?
Management of factor XI deficiency is individualised, ranging from conservative measures and monitoring through to more active medical or surgical treatment depending on how it's affecting you. A clear diagnosis is the first step towards choosing the right approach.
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How long does factor XI deficiency last?
The outlook for factor XI deficiency varies widely depending on the underlying cause, how early it's diagnosed, and how it responds to treatment. Many people see significant improvement with appropriate care, and your specialist can give you a more personalised timeframe once they've reviewed your case.
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What else could factor XI deficiency be mistaken for?
Because several conditions can share similar symptoms to factor XI deficiency, clinicians often consider a short list of possibilities before confirming a diagnosis. This is one of the main reasons a proper assessment, and sometimes targeted tests, matters more than relying on symptoms alone.
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When should I see a doctor about factor XI deficiency, and how quickly can I be seen privately?
It's worth seeking medical advice if symptoms of factor XI deficiency are persistent, worsening, or affecting your daily life, rather than waiting for them to resolve on their own. NHS routine referrals for this kind of assessment can take anywhere from around 20 to 45+ weeks, whereas private consultants typically offer an appointment within about two weeks.