APS Awareness Month 2026: Patients, science, and clinical trials

Antiphospholipid syndrome, known as APS, is a chronic autoimmune condition that makes the blood far more likely to form clots than it should. The condition does not affect everyone equally. Most people who learn they have APS are women, often in their twenties, thirties, or forties, and the diagnosis usually arrives after a frightening event: a sudden blood clot in the leg or lung, a stroke in a young adult who had no other risk factors, or a series of pregnancy losses with no clear explanation. Men develop APS too, though less often and frequently later, because they do not have pregnancy-related warning signs that prompt earlier testing. APS can be quietly present for years before the first serious problem appears, which is one reason it is so often diagnosed late. Each June, APS Awareness Month draws attention to a disease that is more common than many assume and more manageable than many fear, and to the APS clinical trials working to improve diagnosis, anticoagulation, and pregnancy outcomes for the people who live with it.

What APS Awareness Month is about

APS Awareness Month is observed each June in the United States and in several other countries. The observance is anchored by a US patient advocacy foundation focused on antiphospholipid syndrome, which has worked for two decades to raise public understanding of the condition and to support patients who are often diagnosed only after a serious health event. The color associated with the month is burgundy, and patients, families, and clinicians often wear it during June to show solidarity.

The month exists for one main reason: APS is widely under-recognized, even by some healthcare professionals. Many people who carry the antibodies that cause APS do not know they have them until a clot or pregnancy complication forces a workup. Awareness efforts during June focus on the warning signs to ask a doctor about, the testing process that confirms a diagnosis, and the research that is gradually expanding what is known about who is most at risk and how the condition can be managed.

For a wider view of how research attention can change the pace of progress for less common diseases, Hope in Research: How Clinical Trials Are Transforming Rare Disease Treatment describes how visibility for an under-recognized condition can move research forward.

Antiphospholipid syndrome explained

Antiphospholipid syndrome is an autoimmune condition. In an autoimmune condition, the immune system makes a mistake. Instead of attacking only threats from outside the body, like viruses or bacteria, it produces antibodies (the proteins the immune system makes to fight invaders) that mistakenly target some of the body's own normal proteins. In APS, those antibodies attach to proteins on the surface of blood cells and the inner lining of blood vessels. The result is that the blood is far more likely to form clots than it would in a person without the antibodies.

A common misconception is that APS damages organs directly, the way some autoimmune conditions like lupus or rheumatoid arthritis do. APS does not work that way. The harm comes from the clots themselves. When clots form in the veins of the legs, they can cause swelling and pain; if they travel to the lungs, the result is a pulmonary embolism, which can be life-threatening. When clots form in arteries that supply the brain, the result is often a stroke, sometimes in a person young enough that no one was looking for one. During pregnancy, clots in the small blood vessels of the placenta can cut off the developing baby's supply of nutrients and oxygen, leading to repeated miscarriage, stillbirth, or preeclampsia (a serious blood-pressure complication that can develop during pregnancy).

A diagnosis takes time. Two separate blood tests, drawn at least 12 weeks apart, must both show the same antibodies. Because that waiting period is built into the diagnostic criteria, and because the symptoms can look like other conditions, many people live with APS for years before it is named.

For a plain-language overview of how clinical trials are designed and what they are for, Clinical Trials Explained: Simple Guide for Beginners covers the basics that the rest of this article builds on.

Who APS affects

APS is not evenly distributed across the population. It is more common in women than in men, and it often appears in adults who are still in their reproductive years. That pattern matters, because it shapes who is most likely to encounter the disease and how it tends to present.

A young woman who has an unexpected stroke, a middle-aged person with a deep vein thrombosis (a blood clot in a deep leg vein, often shortened to DVT) and no clear risk factors, and an expectant mother who has had two or three early miscarriages without a known cause are all people whose doctors should consider APS testing. The condition can also be present in people who already have another autoimmune disease, especially lupus; this is called secondary APS. When APS appears without any other autoimmune condition, it is called primary APS.

Men with APS are sometimes overlooked because the awareness conversation and many of the diagnostic pathways are organized around pregnancy. A man who has a deep vein thrombosis, a pulmonary embolism, or a stroke at a younger age than expected can also have APS, and the same antibody testing applies. Some research suggests that men diagnosed with APS have a higher proportion of arterial events, such as strokes and heart attacks, than women, partly because they are often diagnosed later. APS testing should be on the table whenever an unexplained clotting event happens at a young age, regardless of sex.

Estimates suggest that some level of antiphospholipid antibodies can be found in roughly 1 to 5 out of every 100 people in the United States, though far fewer go on to develop the full syndrome with clots or pregnancy complications. The gap between how many people carry the antibodies and how many actually develop disease is one of the open questions current research is working to answer.

For a closer look at how clinical research engages communities that are often under-represented or under-diagnosed, Maximizing Diversity: Engaging Underrepresented Communities explores the work that goes into reaching the patients who most need access to studies.

How research is advancing care

Most people with APS will need to take medications that prevent blood clots, called anticoagulants (commonly known as blood thinners), often for life. Standard care has long centered on older blood thinners that work well but require frequent blood testing to make sure the dose is right. A great deal of recent research has focused on whether newer blood thinners that do not need that ongoing monitoring can be used safely in APS, or whether some patients are better off staying with the older medication. The answer turns out to be different for different groups of patients, which is one of the reasons clinical trials in APS continue to be needed.

Research has also focused on pregnancy. For decades, the standard approach to pregnancy in APS has been a combination of low-dose aspirin and a specific kind of blood thinner during pregnancy and after delivery. Active studies are looking at whether targeted immune therapies can further reduce the risk of pregnancy loss in patients whose APS does not respond well to the standard approach. Other studies are following patients over time to understand what predicts who will have a smooth pregnancy and who will need closer monitoring.

Based on a search of public trial registries in June 2026, roughly 36 APS clinical trials are actively recruiting participants worldwide, with about 7 in the United States. Eight of these globally are in Phase 2 or Phase 3, which means they are far enough along to test how well a new approach actually works rather than just check that it is safe to give. These counts shift as trials open and close, so the exact numbers will look different a few months from now. They describe a research field that is consistent and active, even if smaller in scale than oncology or cardiovascular research. For comparison, the broader field of recruiting autoimmune disease studies in the United States runs to roughly 650 trials, placing APS research as one focused part of a much larger autoimmune effort.

For a wider perspective on how research moves from study to standard of care, How Clinical Trials Advance Medicine and Change Lives walks through that journey.

Clinical trials in APS today

APS clinical trials currently recruiting fall into a few broad categories. Some are testing whether newer blood thinners can match or improve on older ones for specific kinds of APS patients. Some are studying how to prevent pregnancy complications in patients who are planning or already in a pregnancy. Some are looking at the immune system itself and asking whether quieting the autoimmune process at its source can change the long-term course of the disease. And some are observational, following large groups of patients over time to learn what predicts who does well, who needs more intensive care, and what factors raise the risk of catastrophic antiphospholipid syndrome (CAPS), a rare but life-threatening form in which clots form rapidly in many small blood vessels at once.

A few concerns come up often when people start thinking about whether a study could be right for them. One concern is that joining a study means giving up current blood thinners. In most modern APS trials, the design is built around standard of care, not against it; new approaches are tested in addition to, or in direct comparison with, the medications a patient is already on, not by stopping them. Another concern is that clinical trials are only for advanced or severe cases. In APS, research includes patients across the spectrum, including people who carry the antibodies but have not yet had a clot, and pregnant patients with a history of pregnancy loss. A third concern is uncertainty about the unknowns of a study. Every clinical trial follows a written plan, called a protocol (the document that defines how a study is run), and every participant goes through a careful consent conversation with the research team before agreeing to take part.

DecenTrialz helps people in the United States find clinical trials that may fit their situation. After someone shares basic information about themselves and the conditions they are interested in, the platform may identify trial options that appear to match their profile. A registered nurse then completes an initial pre-screening review before the person is referred to the research site running the study. The research site and study team handle the walk-through of study details, the final eligibility check, the consent conversation, and enrollment, since they are the ones responsible for the participant's care during the trial. You can start a search at decentrialz.com.

For a step-by-step look at how the path from interest to enrollment usually unfolds, How to Find and Enroll in a Clinical Trial: A Step-by-Step Guide walks through what to expect.

What June asks of everyone involved

For patients and the people who love them, APS Awareness Month is an invitation to take warning signs seriously and to ask about testing when a clot, a stroke at a young age, or a pattern of pregnancy loss is part of the picture. Early diagnosis changes outcomes, and the path to a diagnosis often begins with a question asked at the right time.

For doctors and the wider clinical research community, the month is a reminder that APS sits in the category of under-recognized autoimmune disease that benefits from research participation, even when the field is smaller than higher-profile areas of medicine. Each enrolled participant moves the science forward.

And for anyone exploring whether a current APS study fits their situation, June is a good time to look at what is recruiting. You can begin a search at decentrialz.com to see what is currently available.