Antiphospholipid syndrome

About antiphospholipid syndrome

Antiphospholipid syndrome is a condition in which your blood is at a higher risk of clotting than usual. Because of the high tendency of your blood to clot, the condition is often referred to as 'sticky blood'.

Antiphospholipid syndrome is an autoimmune disease. This means that it's caused by antibodies from your immune system attacking your own body by mistake.

If you have antiphospholipid syndrome, your antibodies attack proteins and phospholipids (a type of fat) in your blood. When the antibodies bind to these proteins and phospholipids, the consistency of your blood changes and it becomes more likely to clot.

Antiphospholipid syndrome affects adults and children. It's most common in adults aged between 20 and 50.

Types of antiphospholipid syndrome

There are two types of antiphospholipid syndrome.

  • Primary antiphospholipid syndrome. This is when the disease occurs on its own. Six or seven out of every 10 people with the disease have this form of it.
  • Secondary antiphospholipid syndrome. This is when the disease is related to another condition, most commonly another autoimmune disease called systemic lupus erythematosus.

Symptoms of antiphospholipid syndrome

If you have antiphospholipid syndrome, clots are more likely to form in your arteries or veins. Many people do not get any symptoms of antiphospholipid syndrome, and only become aware they have the condition when they get a blood clot. These clots can be associated with serious health problems, which are listed in the complications section below.

If you do notice any symptoms earlier on, they may include the following.

  • Eyesight problems, including double vision and sudden loss of vision.
  • Headaches and migraines.
  • Livedo reticularis. This is when red, blotchy patches appear on your skin.
  • Ulcers and nodules (bumps) on your skin.

Complications of antiphospholipid syndrome

As blood clots can form in arteries and veins in any part of your body, there are a number of problems that can be caused by antiphospholipid syndrome. However, not everybody with antiphospholipid antibodies in their blood will get a blood clot, or any other problems caused by the condition. The following is a list of some of the possible complications.

Deep vein thrombosis (DVT)

  • A DVT is a blood clot that forms in one of your deep veins, most commonly in your leg. Symptoms include pain and swelling.


  • Pulmonary embolism. This is a clot in one of the blood vessels in your lungs. It usually comes from a DVT in your leg and travels in your blood to your lungs. It can cause you to have chest pains, shortness of breath and to cough up blood. A pulmonary embolism can be fatal if the clot is very large.


  • Recurrent miscarriage. Clots can reduce the amount of blood travelling through the placenta to your baby. This means there is a higher risk of you having a miscarriage.
  • Pre-eclampsia. This is a condition that causes high blood pressure during pregnancy. You’re at greater risk of developing pre-eclampsia if you have antiphospholipid syndrome.

Nervous system (brain and spinal cord)

  • Stroke. Stroke is a serious condition, caused when the blood supply to part of your brain is cut off. It can cause weakness or paralysis, usually just on one side of your body, slurred speech and confusion. Your doctor will usually consider antiphospholipid syndrome if you have a stroke and are under the age of 45.
  • Memory loss. This can sometimes develop if you have a clot in a blood vessel to your brain.


  • Heart attack. If a clot blocks an artery that supplies your heart with blood, it causes a heart attack. Symptoms of a heart attack include chest pain, pain in your arms or jaw and shortness of breath.
  • Valve disease. Antiphospholipid syndrome can affect how the valves in your heart work. This means that blood can't flow through your heart properly. Symptoms of this include tiredness, breathlessness and swollen ankles.

Digestive system

  • If the blood supply to your bowel is affected by a clot, it can cause pain in your abdomen (tummy), fever (a high temperature) and blood in your faeces. This may require emergency surgery.


  • Thrombocytopenia. This is when your blood has a low level of platelets (fragments of cells that help the blood clot).

A small number of people with antiphospholipid syndrome develop a very rare, but serious, complication known as catastrophic antiphospholipid syndrome. In catastrophic antiphospholipid syndrome, you develop blood clots in many different organs within days or weeks of each other. It can be fatal, even if you have treatment.

An infection, such as a sore throat or chest infection can trigger catastrophic antiphospholipid syndrome. It can also happen if someone with antiphospholipid syndrome stops taking their medication, but this is rare. Catastrophic antiphospholipid syndrome affects fewer than one in every 100 people with the disease.

Causes of antiphospholipid syndrome

If you have antiphospholipid syndrome, your blood contains antiphospholipid antibodies that make your blood more likely to clot. The exact reasons why some people have these antibodies aren't fully understood at present. Generally, the higher the levels of antiphospholipid antibodies in your blood, the greater your risk of blood clots.

Diagnosis of antiphospholipid syndrome

You will be diagnosed with antiphospholipid syndrome if you have had one of the problems associated with the condition listed above, and blood tests have shown there to be antiphospholipid antibodies in your blood.

If your GP thinks there's a possibility that you could have antiphospholipid syndrome, he or she will ask you to have a blood test. The doctor or nurse will take a sample of your blood and send it to a laboratory for testing. Your blood will undergo a series of tests including a blood count, which measures the amount of different cells in your blood. It will also be tested for three antiphospholipid antibodies – anticardiolipin antibody, lupus anticoagulant and anti-beta2-glycoprotein I antibody. If the tests show you have one or more of these antibodies in your blood, they are usually repeated at least 12 weeks later, to confirm that the antibodies are still there.

Your GP may refer you to another doctor, depending on what type of symptoms you have. For example, you may need to see a haematologist (a doctor who specialises in blood disorders) or an obstetrician (a doctor who specialises in pregnancy and childbirth).

Treatment of antiphospholipid syndrome

Not everyone who has antiphospholipid antibodies in their blood will have health problems associated with them. So some people do not need treatment for the condition.

Your doctor will usually prescribe an anticoagulant (anti-clotting) medication for you to take if he or she thinks you need treatment. This will thin your blood and reduce the likelihood of it clotting. There are three drugs you may be prescribed – aspirin, heparin and warfarin.

If you have antiphospholipid syndrome but haven't had a blood clot, you may be prescribed a low dose of aspirin to take every day. More research needs to be done to know for sure whether low-dose aspirin is helpful at preventing symptoms in people with antiphospholipid syndrome who have no history of blood clots.

If you have had a clot in one of your blood vessels, you will usually be prescribed either heparin or warfarin. You can only have heparin as an injection and it isn't usually prescribed long-term. Most people take warfarin in a tablet form. You will often need to take anticoagulation drugs for the rest of your life.

If you're pregnant, you will be prescribed aspirin or heparin, or often both. This is because warfarin could harm your unborn baby.

If you're taking warfarin, your blood will be regularly monitored with a clotting test. This can be done at your GP surgery or at a hospital clinic. Sometimes, people can test their blood themselves using a special self-testing machine.

Prevention of blood clots

There are several things you can do to reduce your risk of getting blood clots if you have antiphospholipid syndrome.

  • If you smoke, try to stop.
  • Maintain a healthy weight and exercise regularly.
  • If you are a woman, talk to your GP about the most suitable contraception for you. The contraceptive pill can increase your risk of blood clots, so you may prefer to use another form of contraception.

With the right treatment and lifestyle changes, most people with antiphospholipid syndrome can live a normal, healthy life.

What type of doctor will I need to see to be treated for antiphospholipid syndrome?


Your GP may refer you to a number of different doctors, depending on the symptoms you have, and which parts of your body are affected.


Antiphospholipid syndrome can cause many different symptoms, depending on which of your organs are affected. You may need to see:

  • a rheumatologist – a doctor who specialises in conditions affecting your musculoskeletal system
  • an obstetrician – a doctor who specialises in pregnancy and childbirth; you may need to see an obstetrician who has special experience in high-risk pregnancies
  • a neurologist – a doctor who specialises in disorders of the nervous system
  • a cardiologist – a doctor who specialises in conditions of the heart
  • a respiratory physician – a doctor who specialises in conditions of the lungs
  • an ophthalmologist – a doctor who specialises in eye health
  • a haematologist – a doctor who specialises in blood disorders
  • a hepatologist – a doctor who specialises in conditions of the liver

Your GP will tell you the most appropriate type of doctor to see and will need to refer you.

Do medicines for antiphospholipid syndrome have any side-effects?


Yes, it's possible that you may get some side-effects while taking medicines for antiphospholipid syndrome. However, you will be monitored to try and reduce the risk of any serious side-effects.


There are three drugs that are commonly prescribed to treat antiphospholipid syndrome. Two of these are anticoagulant (anticlotting) drugs – heparin and warfarin. The other is aspirin, an antiplatelet agent.

The main side-effect of warfarin is internal bleeding or excessive bleeding from broken skin. Side-effects are less common if you're regularly monitoring your blood with clotting tests. To make sure you're taking the right dose, you will need to have regular blood tests. These tests can be done at your GP surgery or a hospital clinic. You may also be able to test your blood yourself using a self-testing machine.

Heparin can also cause internal and external bleeding. If used for long periods of time at high doses, it can increase your risk of getting osteoporosis. This is a condition that gradually causes your bones to become more fragile. Usually, you will only be prescribed heparin for a short period of time, for example when a clot is first diagnosed or if you're pregnant and have suffered from complications during pregnancy in the past.

Taking heparin can lead to thrombocytopenia. This is when your blood has a low level of platelets (molecules that help the blood clot). However, this is rare. If you develop thrombocytopenia while taking heparin, you must stop taking it immediately. If you're taking heparin for a longer than a week, your doctor will check your platelet count five to seven days after you start taking the drug.

Aspirin can have some side-effects that affect your stomach and bowel, including indigestion. People with asthma may be allergic to aspirin, so make sure you tell your GP or specialist if you have asthma.

How long will I need to take anticoagulation medication for?


If you have had a blood clot caused by antiphospholipid syndrome, you will probably need long-term anticoagulant treatment.


Treatment of antiphospholipid syndrome is aimed at thinning your blood, to reduce the likelihood of it clotting.

If you have antiphospholipid syndrome and have had a blood clot, there is a high risk of you developing another one if you stop taking your medication. Therefore, you will probably need to take medication for the rest of your life.