Health condition
Antiphospholipid syndrome
Antiphospholipid syndrome is an acquired autoimmune condition causing clots in veins and arteries and pregnancy complications; it is one thrombophilia diagnosis that genuinely changes treatment - usually warfarin rather than newer anticoagulants.
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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Clinical picture: unprovoked DVT and pulmonary embolism, strokes in younger people, and pregnancy morbidity - recurrent early miscarriage, later losses, severe early pre-eclampsia
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Diagnosis requires both events AND persistent antibodies (lupus anticoagulant, anticardiolipin, anti-beta-2-glycoprotein) confirmed at least 12 weeks apart
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Treatment specifics: warfarin outperforms DOACs for thrombotic APS (especially arterial and triple-positive disease); pregnancy care uses aspirin plus heparin with high success rates
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Specialist: a consultant haematologist or rheumatologist; APS can occur alone or with lupus, and triple-positive patients need the most attentive management
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
Antiphospholipid syndrome sits at the junction of immunology and coagulation: autoantibodies against phospholipid-binding proteins create a persistent prothrombotic state capable of clotting veins and - unusually among thrombophilias - arteries, making it a cause worth seeking in unprovoked thromboses, strokes and heart attacks in the young, and in a distinctive pattern of pregnancy complications spanning recurrent early miscarriage, unexplained later fetal loss and severe early-onset pre-eclampsia. The diagnosis deliberately demands persistence: transient antibodies follow infections commonly, so laboratory criteria require positivity on two occasions at least twelve weeks apart, across three antibody tests whose combined positivity (triple-positive status) marks the highest-risk patients.
Diagnosis and treatment routes
APS rewrites treatment rules that apply elsewhere: after thrombosis, anticoagulation is generally indefinite, and trial evidence shows warfarin protects better than direct oral anticoagulants in significant subgroups - particularly arterial and triple-positive disease - a distinction patients switched to newer agents for convenience deserve to have revisited. Obstetric APS is one of medicine's quiet success stories: low-dose aspirin plus prophylactic heparin through pregnancy converts high loss rates into live-birth rates most patients find transformative, under joint haematology-obstetric care. Living with APS otherwise centres on vascular housekeeping - blood pressure, lipids, smoking abstinence - awareness that the syndrome may accompany lupus, INR discipline for those on warfarin, and specialist review of any new neurological, cardiac or pregnancy plans; a rare accelerated form involving multiple organs is an emergency patients need only know exists so that severe multi-system illness prompts immediate care. 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 or rheumatologist. 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 Antiphospholipid syndrome.
Quick, plain-English answers to what people ask us most.
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What is antiphospholipid syndrome?
Antiphospholipid syndrome is an autoimmune condition causing the blood to clot more easily than normal, due to specific antibodies, which can lead to blood clots and pregnancy complications.
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What causes antiphospholipid syndrome?
It is caused by the immune system producing antiphospholipid antibodies that disrupt normal blood clotting regulation; it can occur on its own or alongside other autoimmune conditions such as lupus.
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What are the symptoms of antiphospholipid syndrome?
Symptoms include blood clots such as deep vein thrombosis or stroke, recurrent miscarriages, and sometimes a mottled skin appearance, particularly on the legs.
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Is antiphospholipid syndrome serious?
Yes, it significantly raises the risk of serious clotting events like stroke or pulmonary embolism and recurrent pregnancy loss, but with appropriate treatment, many people manage the condition well.
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Can antiphospholipid syndrome be cured?
There is no cure, but long-term blood-thinning treatment can very effectively reduce the risk of future clots and, with specialist care, significantly improve pregnancy outcomes.
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How is antiphospholipid syndrome treated?
Treatment typically involves long-term blood-thinning medication such as aspirin or warfarin, with specific treatment adjustments and closer monitoring recommended during pregnancy.
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How is antiphospholipid syndrome managed during pregnancy?
Pregnancy management typically involves specific blood-thinning medication (often a different regimen than usual) and closer monitoring by a specialist team experienced in high-risk pregnancy care.
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Antiphospholipid syndrome vs Factor V Leiden — what's the difference?
Factor V Leiden is an inherited genetic clotting disorder caused by a specific gene mutation, while antiphospholipid syndrome is an acquired autoimmune condition caused by antibodies; both increase clotting risk but are diagnosed and sometimes managed somewhat differently.
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Does antiphospholipid syndrome always cause symptoms?
No, some people have positive antibody tests without ever developing clots or pregnancy complications, though ongoing monitoring is generally still recommended given the increased risk.
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When should I see a doctor about possible antiphospholipid syndrome, and how quickly can I be seen privately?
See a doctor for unexplained blood clots or recurrent miscarriage. NHS haematology or rheumatology referral can take several weeks, while private specialist assessment is often available within about two weeks.