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Antiphospholipid syndrome

Also called: Antiphospholipid syndrome, APS, sticky blood

An immune condition that makes blood clot too easily, causing blood clots, strokes, and pregnancy losses.

TreatmentBlood thinners

Overview

APS is often found after an unexplained clot or several miscarriages.

It can happen alone or with lupus.

Symptoms

Common signs:

  • Blood clots

Less common

  • Pregnancy loss
  • Stroke

When to get medical care

Call 911Sudden face drooping, arm weakness, trouble speaking, or vision loss: call 911.
Get care todayLeg swelling.
See a doctor soonPregnancy planning.

Causes

Immune.

Does it spread or run in families?

  • It isn't contagious. You can't catch it from someone else.

Who is more likely to get it

  • Lupus

Possible complications

Diagnosis

A clinician asks about your symptoms and may order tests.

The exam

A physical exam.

Tests

Tests, if needed:

  • Antibody tests:

Treatment

Treatment depends on the cause and how severe it is.

Self-care

  • Take blood thinners
  • Don't smoke

Prevention

To lower your risk or prevent problems:

  • Don't smoke

Which doctor treats this

  • Start with your primary care provider (family doctor or internist).
  • They may send you to a rheumatologist (joint and immune system doctor).

Living with it

Support groups and helplines

Children, pregnancy, and older adults

  • Pregnancy: Needs special care with blood thinners.

Pregnancy and breastfeeding

  • If you're pregnant or planning to be, tell your prenatal provider about this condition.
  • Don't start or stop any medicine on your own. Some are safe in pregnancy and some need to be changed.
  • Ask before taking any pain reliever. The FDA advises avoiding ibuprofen and naproxen after 20 weeks unless your doctor says to.
  • Breastfeeding: Most medicines are fine, but ask. The NIH LactMed database lists what's known about each one.

Outlook

Treatment lowers clot risk.

Blood thinners help.

Getting ready for your visit

Bring a list of your symptoms and medicines.

What to bring

  • A list of your medicines and supplements
  • Notes on when symptoms started and what makes them better or worse

Questions to ask

  • What's causing this?
  • What treatment do you recommend?
  • How long will I take blood thinners?

Research studies

Research studies test new ways to find and treat health problems. Some are looking for volunteers. Talk with your doctor before joining one.

Search ClinicalTrials.gov for studies on Antiphospholipid syndrome

Sources

Last updated 2026-11-12.