This condition can cause blood clots, resulting in a range of possible complications including miscarriage.

Antiphospholipid syndrome is an autoimmune disorder in which the immune system attacks phospholipids.

Phospholipids are fatty substances that are a normal part of all of your body's cells.

But if your immune system mistakes phospholipids in your body's cells as foreign invaders, it sends antibodies to attack and damage them.

This damage encourages the formation of blood clots.

Causes and Risk Factors

Antiphospholipid syndrome – also known as Hughes syndrome – can occur in anyone, at any age.

However, you're at greater risk for antiphospholipid syndrome if you:

  • Are female
  • Have other autoimmune conditions, such as rheumatoid arthritis or lupus
  • Develop infections such as syphilis, Lyme disease, hepatitis C, or HIV/AIDS
  • Take certain medications, such as the antibiotic amoxicillin, the epilepsy drug Dilantin (phenytoin), the blood pressure drug hydralazine, or the heart medicine quinidine
  • Have a family member with the disorder

Symptoms and Complications

Symptoms of antiphospholipid syndrome depend on where the blood clots form (in arteries or in veins).

Antiphospholipid syndrome can cause a variety of medical problems, including:

  • Repeated pregnancy losses (miscarriage and stillbirth)
  • Preeclampsia (a condition in pregnant women that can cause high blood pressure, kidney problems, and swelling)
  • Premature birth
  • Low birth weight
  • Stroke
  • Heart attack
  • Kidney problems
  • Blood clots in the legs (deep vein thrombosis, or DVT) and/or lungs (pulmonary embolism)
  • High blood pressure in the lungs (pulmonary hypertension)
  • Areas of bone death
  • Migraine headaches
  • Seizures
  • Bleeding episodes

Not everyone with the antibodies that cause antiphospholipid syndrome will experience problems with blood clotting.

Some people never have symptoms or medical problems from the disorder.

In other cases, symptoms may begin after certain events or conditions, such as:

  • Pregnancy
  • Surgery
  • Smoking cigarettes
  • Using oral contraceptives
  • Developing high cholesterol or triglycerides
  • Long sedentary periods due to illness, injury, or plane travel


Antiphospholipid syndrome is diagnosed by testing for certain antibodies in the blood.

The disorder is diagnosed if these antibodies are seen in two separate blood tests, done at least 12 weeks apart.

Antiphospholipid Syndrome Treatment

Antiphospholipid syndrome is treated with medications called blood thinners, which can stop more blood clots from forming.

Taking blood thinners requires extreme caution during pregnancy, but these drugs can help women with antiphospholipid syndrome successfully carry a baby.

Blood thinners can also prevent further problems that may result from strokes or other organ damage caused by antiphospholipid syndrome.

Editorial Sources and Fact-Checking

  • Antiphospholipid syndrome; Genetics Home Reference.
  • What Is Antiphospholipid Antibody Syndrome? National Heart, Lung, and Blood Institute.


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