Home / initial_treatment / How does fondaparinux work?

How does fondaparinux work?

Fondaparinux (Arixtra®) differs from standard heparin and LMWH in several ways. In particular, it does not come from animal sources. Instead, this drug is a synthetic version of the active site of the heparin molecule and is an even smaller molecule than LMWH. Heparin blocks both thrombin and factor Xa, whereas LMWH has relatively more activity against factor Xa and relatively less activity against thrombin. By contrast, fondaparinux acts exclusively against factor Xa—it does not affect thrombin. Fondaparinux does not require monitoring.

Current News

Jennifer Luft

Apply for the Jennifer Luft Emerging VTE Clinician Research Award

The Jennifer Luft Emerging VTE Clinician Research Award is named in memory of Jennifer Luft, who suffered from pulmonary emboli…

Get the full story »

candid-seal-platinum-2026

Maintaining Trust: NBCA Earns Candid’s Platinum Seal of Transparency for 2026

Trust and transparency are essential to the work of nonprofit organizations, especially those dedicated to saving lives and supporting patients…

Get the full story »

Get more news »

Follow us on Instagram

stoptheclot

Advancing blood clot awareness, prevention, diagnosis & treatments to #stoptheclot. Submit your story @ link below ⬇️ Our podcast: Taking a Breath 🎙️

🎙️ New Episode Alert! 🎙️Season 3, Episod

🎙️ New Episode Alert! 🎙️Season 3, Episode 5 of Taking a Breath: A Stop the Clot podcast is now available on all major podcast platforms.

In this episode, listeners hear from Florida Senator @shevrinjones, a blood clot survivor who also lost a brother to a pulmonary embolism.

Like many survivors, Jones has lived with the ongoing anxiety and fear of recurrence. This personal experience drove him to become a key proponent of the Emily Adkins Family Prevention Act, which was signed into law in 2025.

It established the Blood Clot and Pulmonary Embolism Policy Workgroup, aimed at reducing preventable deaths from blood clots in Florida through improved screening, awareness, and data collection.

This is a step in the right direction, although much work needs to be done in terms of awareness, he said.

“People are not educated on it,” Jones said.

Thank you, Senator Jones, for sharing your story and helping raise awareness.

Listen to his journey on our website or wherever you get your podcasts: Link in bio.

#StopTheClot #ShevrinJones #FloridaPolitics #BloodClots

A severe headache. Vision changes. Difficulty talk

A severe headache. Vision changes. Difficulty talking. Dizziness and confusion.

These symptoms could be caused by cerebral venous sinus thrombosis (CVST), or a blood clot in the brain. Diagnosis is often delayed because symptoms can be mistaken for migraines, stress, or anxiety.

In our February PEP Talk on Tuesday, Feb. 10 at 7 p.m. ET, we’ll discuss CVST and other uncommon blood clots, including how to recognize red flags and advocate for imaging when symptoms don’t add up.

📅 Feb. 10 | 7 p.m. ET
👉 Register: Link in bio.

#StopTheClot #BloodClots #CVST #PEPTalk

Florida Senate President Ben Albritton is receivin

Florida Senate President Ben Albritton is receiving care for a pulmonary embolism — a powerful reminder that blood clots can happen suddenly and require immediate attention.

Sen. Albritton has been a strong advocate for the Emily Adkins Family Protection Act, advancing lifesaving blood clot awareness and prevention in Florida.

We wish him a full recovery and urge everyone: know the signs, trust your instincts, and seek care immediately.

🔗 Know the signs of blood clots → Link in bio.

🔗 Learn about the Emily Adkins Family Protection Act → Link in bio.

#StopTheClot #PulmonaryEmbolism #BenAlbritton #FloridaPolitics #EmilyAdkinsFamilyProtectionAct

A blood clot diagnosis can turn your world upside

A blood clot diagnosis can turn your world upside down. Questions, fear, and uncertainty are normal, but you don’t have to navigate it alone.

NBCA’s New Patient Guide was created by patients, for patients, to help you understand what comes next after a blood clot diagnosis. It walks through the typical stages of the blood clot journey — diagnosis, treatment, recovery, and prevention — and explains what to expect at each step.

Whether you’ve been diagnosed with a DVT, PE, or another type of blood clot — or you’re caring for someone who has — this guide is here to support you every step of the way.

Download or order copies in English or Spanish: Link in bio.

#StopTheClot #BloodClots #NewPatientGuide #PulmonaryEmbolism #DeepVeinThrombosis #CVST

Did you know blood clots don’t only happen in th

Did you know blood clots don’t only happen in the lungs or legs?

When clots form in uncommon locations, symptoms are often overlooked, and diagnosis can be dangerously delayed.

In our February PEP Talk, we’re joined by Dr. Stephan Moll, internationally recognized VTE expert, and professor of medicine and hematologist at the University of North Carolina School of Medicine.

Dr. Moll — whose work has shaped how clinicians worldwide diagnose and manage blood clots— will break down what patients and caregivers need to know about clots that don’t fit the “classic” picture.

We’ll cover:

• Where uncommon blood clots most often occur

• Symptoms that are frequently misdiagnosed or dismissed

• When imaging matters and which tests to ask about

• Risk factors for atypical clots

• How to advocate for yourself when something doesn’t feel right

📅 Tuesday, February 10 | 7 p.m. ET

🔗 Register: Link in bio.

#StopTheClot #BloodClots #CVST #AtypicalBloodClots

Calling early-career VTE researchers 📣 The Nati

Calling early-career VTE researchers 📣 The National Blood Clot Alliance is now accepting applications for the 2026 Jennifer Luft Emerging VTE Clinician Research Award.

This $20,000 award supports early-career scientists and clinicians working to advance patient-centered research in venous thromboembolism (VTE). Eligible projects may span basic, translational, clinical, epidemiologic, bioengineering, or related fields, with a focus on improving care, access, quality of life, shared decision-making, or health equity for people affected by blood clots.

This award honors the life of Jennifer Luft, who suffered pulmonary emboli at age 23, resulting in a severe anoxic brain injury. Inspired by Jennifer’s strength and the devotion of her family, NBCA established this award to support the next generation of researchers committed to advancing the understanding and treatment of VTE through patient-oriented research.

👉 Application deadline: February 27, 2026 at 11 p.m. ET

🔗 Learn more about eligibility and apply: Link in bio.

#StopTheClot #BloodClots #VTEResearch #VTEClinician #BloodClotResearch #JenniferLuft

We’re proud to share that the National Blood Clo

We’re proud to share that the National Blood Clot Alliance has once again earned Candid’s Platinum Seal of Transparency.

This marks our second consecutive year receiving Candid’s highest level of recognition, placing NBCA among fewer than 1% of U.S. nonprofits that meet the most rigorous standards for transparency and accountability.

For our supporters, this seal reflects our commitment to openly sharing how we operate, how we use donor support, and the impact of our lifesaving blood clot awareness and education programs.

Transparency isn’t a one-time achievement, it’s a responsibility we take seriously, year after year.

Read more: Link in bio.

#StopTheClot #BloodClots #VTE #CandidPlatinumSeal #NonprofitExcellence

@CandidDotOrg

As told by Justin’s mother, Lauren:

“Justin’s experience with blood clots started as back pain after a hockey tournament. We went to the ER and were told it was spasms and to follow up with an orthopedic doctor.

Justin was diagnosed with a bulging disk and started physical therapy. In a month, we went to two ERs, an orthopedic specialist, two chiropractors, and a physical therapist to find answers.

By week four, we expressed concern to his strength coach because his legs felt tired, heavy, and swollen. He suggested pushing for another scan and blood work.

We took Justin to the hospital, where scans showed clots that began in his inferior vena cava vein in the abdomen and went down to the knees. He was admitted and started on heparin.

The next three days consisted of three surgeries. But after eight hours into the second surgery, his surgeon said that the clots turned into scar tissue and couldn’t be removed. But after eight more hours in the OR, they were able to remove the majority of the clots.

With no definitive reason why this happened, we went home on enoxaparin shots twice per day. He tested negative for genetic clotting disorders. It’s assumed that the clots were caused by dehydration and the long car ride, and turned into scar tissue because they were present for about four weeks. If a simple blood test been done, the clots would’ve been found earlier and wouldn’t have progressed.

Determined to return to the ice, his amazing hematologist agreed to learn from other doctors who work with athletes who have had clots. He looked at the whole child. Without hockey, Justin was susceptible to depression and anxiety; a return to normal life was imperative.

Justin returned to the ice three months later, on his 16th birthday. After his diagnosis, I found the National Blood Clot Alliance online. Advocating for your child and yourself is extremely important. Doctors told us he'd never play hockey again, but I knew there were alternatives because of NBCA’s website.

Find doctors who will listen. Justin’s clots progressed because he didn't fit the criteria. We are forever thankful to his coaches, doctors, and nurses who listened and saved him.”

❤️‍🩹 Life after a blood clot isn’t just

❤️‍🩹 Life after a blood clot isn’t just physical, it can take a real mental and emotional toll, too.

Our private Facebook support group connects more than 11,000 survivors and caregivers who get it—the fears, questions, and feelings that can be hard to explain to anyone who hasn’t lived it. It’s a space to be honest, feel understood, and learn from others who’ve walked the same path.

If you’re navigating life after a blood clot, you don’t have to do it alone.

💬 Join the community: Link in bio.

#StopTheClot #BloodClots #BloodClotSupportGroup #PeerSupport

January 23 is Maternal Health Awareness Day, and w

January 23 is Maternal Health Awareness Day, and we want to bring attention to one of the most common causes of pregnancy-related death in the United States: pulmonary embolism, a blood clot in the lung.

Pregnancy and the postpartum period significantly increase the risk of blood clots. Women are five times more likely to experience a pulmonary embolism during pregnancy and in the three months after delivery. The risk is even higher after surgical delivery — a cesarean section doubles a woman’s risk of developing a PE.

Symptoms of pulmonary embolism, such as shortness of breath, chest pain, a rapid heart rate, or feeling faint, are often mistaken for normal pregnancy changes. When warning signs are missed or dismissed, diagnosis and treatment can be dangerously delayed.

This year’s theme, holding ground on maternal health, reinforces the fact that pregnant and postpartum patients need to be taken seriously, evaluated promptly, and given access to lifesaving care.

If you are pregnant or planning to become pregnant, talk with your healthcare provider about your blood clot risk and a personalized blood clot prevention plan. Early recognition, prevention, and action can save lives.

Learn more: Link in bio.

#StopTheClot #MaternalHealthAwarenessDay #Pregnancy

“I am a 24-year-old first-year medical student.

“I am a 24-year-old first-year medical student. On December 18, 2025, I was diagnosed with a pulmonary embolism, a life-threatening condition that requires prompt recognition and treatment.

That day, I initially presented the emergency department with severe shortness of breath, near-syncope (fainting), and a rapid heart rate (tachycardia). I explicitly expressed that I felt like I was going to pass out, was unable to breathe normally, and needed immediate assistance. Despite these classic red-flag symptoms, the triage nurse dismissed my concerns.

Because of this dismissal and lack of appropriate response, I made the decision to leave and seek care elsewhere. I went to another hospital, where I was immediately evaluated. The medical team there promptly recognized the severity of my condition, diagnosed a pulmonary embolism, and performed an emergent thrombectomy, which ultimately saved my life. I was explicitly told by physicians that had I not advocated for myself and left the first hospital, I would likely not have survived.

My experience with a blood clot has had a lasting emotional and physical impact. I continue to struggle with medical trauma, and as a medical student, I am experiencing moral injury due to feeling dismissed, a lack of empathy, and a lack of accountability within the healthcare system.

Since this experience, I have learned the importance of patient self-advocacy, listening to bodily warning signs, and recognizing how profoundly medical trauma can affect recovery. The NBCA resources have been helpful in better understanding my diagnosis and what recovery entails.

My advice is to advocate for yourself relentlessly and listen to your body. Trust your instincts, seek care elsewhere if needed, and never hesitate to ask for help.”

More stories: Link in bio.

#StopTheClot #StopTheClotStory #Gaslighting #MedicalTrauma #PE

Thank you to everyone who joined us for our journa

Thank you to everyone who joined us for our journal club session this week!

If you missed it, we discussed a paper published in Thrombosis Research titled, “Antithrombin Testing and Treatment in Pregnancy: Their Real-World Relationship to Clinical Outcomes.”

The discussion included the paper’s author, Dr. Jerome (Jeff) Federspiel of Duke University Medical Center, as well as Dr. Emily Nagler of Scripps Health, and Drs. Zachary Schoepflin and Ishan Tatake of Beth Israel Deaconess Medical Center.

Watch the recording at the link in bio.

#StopTheClot #AntithrombinTesting #Pregnancy #BloodClots #JournalClub

Blood clots don’t always show up where you expec

Blood clots don’t always show up where you expect them.

Beyond the legs and lungs, blood clots can form in less common—and often overlooked—areas of the body. This can lead to delayed treatment, confusing symptoms, and serious complications if not recognized early.

In this upcoming PEP Talk, expert guest Dr. Stephan Moll of the University of North Carolina will break down what patients and caregivers need to know, including:

- The most frequent uncommon clot locations
- Symptoms that are often misdiagnosed or overlooked
- When to push for imaging and which tests are needed
- Risk factors that raise your chances of an atypical clot

This session will help you recognize warning signs, ask the right questions, and feel more confident navigating the diagnostic process, even when symptoms don’t fit the “typical” picture.

🔗 Register: Link in bio.

#StopTheClot #BloodClots #CVST #AtypicalBloodClots

HAPPENING TODAY: Antithrombin deficiency carries s

HAPPENING TODAY: Antithrombin deficiency carries serious risk in pregnancy, yet real-world testing and treatment remain inconsistent.

Join NBCA’s Journal Club today (3–4 p.m. ET) as Drs. Jerome (Jeff) Federspiel, Emily Nagler, Zachary Schoepflin, and Ishan Tatake discuss a 2024 study published in Thrombosis Research examining real-world patterns of antithrombin testing, treatment, and outcomes in pregnancy.

👉 Register: Link in bio.

@dukeuniversity
@scrippshealth
@bethisraellaheyhealth

#StopTheClot #AntithrombinTesting #Pregnancy #BloodClots #JournalClub

⏱️Thanks to supporters like you, we’re less

⏱️Thanks to supporters like you, we’re less than $20,000 from our $100,000 goal.

Every gift made today is matched dollar-for-dollar, but the opportunity ends tonight.

Plus, donate any amount today and you’ll be entered to win 1 of 5 Stop the Clot® dog bandanas 🐾

Blood clots don’t wait, and awareness only saves lives if it reaches people in time. If you’ve been considering a gift, today is the day it matters most.

👉 Donate now and double your impact before midnight: Link in bio.

#StopTheClot #BloodClotAdvocacy #BloodClotAwareness

How are antithrombin testing and treatment actuall

How are antithrombin testing and treatment actually being used in pregnancy, and what does that mean for patient outcomes?

Our next NBCA Journal Club session on Tuesday, Jan. 21 from 3-4 p.m. ET will examine a 2024 Thrombosis Research article that analyzes real-world patterns of antithrombin testing and treatment in pregnant patients, and how these practices relate to VTE risk, maternal outcomes, and gaps in care.

This panel discussion, with clinicians from Duke University Medical Center, Beth Israel Deaconess Medical Center, and Scripps Health, looks at what’s happening in real clinical settings where earlier testing or intervention may change outcomes.

We hope you’ll join us!

🗓 Wednesday, January 21

⏰ 3–4 p.m. ET | Zoom

REGISTER: Link in bio.

#StopTheClot #AntithrombinTesting #Pregnancy #BloodClots #JournalClub

The National Blood Clot Alliance honors the many a

The National Blood Clot Alliance honors the many accomplishments of Dr. Martin Luther King Jr. on this special day.

His words resonate deeply as we strive for a healthier, more just world: "Of all forms of discrimination and inequalities, injustice in health is the most shocking and inhuman."

Let's unite in the fight against health disparities.

Blood clots happen most often in the legs or lungs

Blood clots happen most often in the legs or lungs, but Tiffani's were in the abdominal veins. Our next PEP Talk on Feb. 10 is focused on blood clots in less common locations and how patients can recognize warning signs.👉 We hope you’ll join us. Register at the link in bio.

⬇️ Read Tiffani’s full story ⬇️

“When I developed my first clot, I was undergoing immunotherapy for stage 4 metastatic melanoma. My regimen was four infusions, five weeks apart, to boost the immune system and help fight the cancer. After that, I received additional infusions at a lower dosage.

At first, I had no side effects other than fatigue, then I was hit with horrible abdominal pain, and was taken to the ER. The diagnosis was mesenteric eschemia, in which where blood flow in the superior mesenteric vein in the intestine is blocked by a blood clot.

I was told to call my family because I would never leave the ICU. But I’m a fighter and told them to just watch me. Somehow, I was discharged a week later and given a prescription for warfarin.

My hematologist tested me for everything, as did a genetics specialist. I carry not a single gene that could explain the clots. (I also carry no cancer genres and yet this was my fourth primary cancer).

I also have long QT syndrome, a heart rhythm disorder, and needed an ablation on my heart. The plan was to go off of enoxaparin for 48 hours prior and then resume the morning after the ablation. Two weeks later, I was back in the ER with a new clot.

My right portal vein is completely occluded, which has caused stage 4 scarring on my liver. My superior mesenteric vein is also occluded. I underwent a procedure where a coil was placed in an attempt to restore blood flow, but it failed within six hours, so I had emergency surgery to remove it. At this point, the doctors tell me the most we can hope for is to prevent new blood clots.

The good news is that I am in remission from the cancer. Now if we could just restore some blood flow. The current plan is enoxaparin for life.

My advice to others: don’t ever miss a dose of medication. And be the squeaky wheel. Fight for yourself, and don’t ever give up!”

More stories: Link in bio.

Most people associate venous blood clots with the

Most people associate venous blood clots with the legs or lungs, but they can form in other parts of the body, too, including the brain, arm, kidneys, and more.

When they do, symptoms are often missed or misdiagnosed, delaying treatment and increasing risk.

In our next PEP Talk on Tuesday, February 10 at 7 p.m. ET, expert guest Dr. Stephan Moll of the University of North Carolina breaks down:

• Where uncommon clots most often occur
• Symptoms that are easy to overlook
• When to push for imaging and which tests matter
• Risk factors for atypical clots
• How to advocate for yourself when something doesn’t feel right

This session will help you recognize warning signs, ask better questions, and feel more confident navigating diagnosis when symptoms don’t fit the typical picture.

👉 Register: Link in bio.

#StopTheClot #BloodClots #DVT #PE #CVST #PEPTalk

“In February 2022, when I was 16 years old, I wo

“In February 2022, when I was 16 years old, I woke up with intense chest pain, shortness of breath, and pain in my left leg. At first, I thought I had COVID-19, as I had no idea what a blood clot was. However, after visiting my pediatrician, I was told to go to the emergency room immediately because she suspected blood clots in both my leg and lungs.

I was admitted to the hospital, but it remained a mystery why an otherwise healthy and active teenager would develop blood clots. After further testing, I was diagnosed with May-Thurner syndrome and triple-positive antiphospholipid syndrome. I later underwent a procedure to place a stent in my left iliac vein, resolving the compression caused by May-Thurner syndrome.

I was also started on twice-daily enoxaparin injections, which I continue to take today, as I require lifelong anticoagulation due to my antiphospholipid syndrome.

I am extremely grateful that nearly four years later, I have remained blood clot–free thanks to the excellent care I have received and continue to receive from my healthcare team.

I have had to avoid participating in contact sports and other risky activities, but still participate in the sports that I love with necessary modifications.

I have learned that anybody can get a blood clot, as blood clots do not discriminate. NBCA has helped in my recovery process, as I have been able to read about blood clot survivors who share similar stories to mine. NBCA has also provided resources to help share the signs of blood clots.

Everyone’s recovery process looks different. My advice is to be patient with yourself and listen to what your body needs.”

More stories: Link in bio.

#StopTheClot #StopTheClotStory #APS #AntiphospholipidSyndrome #MTS #MayThurnerSyndrome #BloodClots

Load More Follow on Instagram