Blood Clot Risk After Achilles Rupture: DVT and PE

When you rupture your Achilles tendon, the focus is naturally on the tendon itself. But there’s a second risk that gets far less attention: blood clots. Being immobilised in a walking boot switches off your calf muscle pump — the mechanism that pushes blood back up to your heart — and this significantly increases your risk of a clot forming in the deep veins of your leg.

This isn’t rare. Research shows that blood clots after Achilles rupture are far more common than most patients realise.

Contents

• Key Takeaways
• Why Achilles Rupture Increases Clot Risk
• DVT vs PE: What’s the Difference?
• How Common Are Blood Clots?
• Warning Signs You Must Know
• Blood Thinners During Recovery
• What You Can Do to Reduce Your Risk
• Frequently Asked Questions
• References

Key Takeaways

• Blood clots are common after Achilles rupture — research finds DVT (deep vein thrombosis) in up to 48% of patients when screened
• Most clots are small and below the knee, but some can travel to the lungs (pulmonary embolism) — a medical emergency
• Blood thinners are typically prescribed for 4–6 weeks during the boot phase, with oral tablets preferred for compliance
• New calf pain, one-leg swelling, breathlessness, or chest pain are red flags that need immediate medical attention
• Walking in your boot and staying as active as your protocol allows helps keep blood flowing

Why Achilles Rupture Increases Clot Risk

Your calf muscles act as a pump. Every time you walk, the muscles contract and squeeze blood upwards through your veins and back towards your heart. When your leg is immobilised in a walking boot, this pump is largely switched off.

At the same time, your body’s natural inflammatory response to the ruptured tendon makes your blood more prone to clotting. This combination — reduced blood flow plus increased clotting tendency — is exactly what creates the conditions for a blood clot to form.

The medical term for this is Virchow’s triad: blood stasis (slow flow), endothelial injury (vessel wall damage), and hypercoagulability (blood that clots more easily). An Achilles rupture ticks at least two of these boxes.

DVT vs PE: What’s the Difference?

These are two stages of the same problem:

Deep Vein Thrombosis (DVT) is a blood clot that forms in the deep veins of your leg, usually in the calf. On its own, a DVT can cause pain, swelling, and long-term damage to the vein (called post-thrombotic syndrome). Many small DVTs, however, cause no symptoms at all.

Pulmonary Embolism (PE) is what happens if part of that clot breaks free and travels through your bloodstream — via the heart — to your lungs. A PE blocks blood flow in the lungs and can be life-threatening. It requires emergency medical treatment.

	DVT (leg clot)	PE (lung clot)
Where	Deep veins of the calf or thigh	Arteries of the lungs
Severity	Painful but treatable	Medical emergency
Key signs	Calf pain, one-leg swelling, warmth	Breathlessness, chest pain, fainting
Action	Contact your clinician urgently	Call emergency services immediately

How Common Are Blood Clots?

More common than you’d expect. A randomised controlled trial by Barfod et al. (2020) screened 130 non-operative Achilles rupture patients with ultrasound at 2 and 8 weeks:

• 48% developed DVT (62 of 130 patients)
• The vast majority were below-knee clots in the calf muscle veins
• Only 3 patients (2.3%) had above-knee DVT
• 1 patient had symptoms — the rest were picked up on screening only
• No patients developed pulmonary embolism

That headline figure — 1 in 2 patients — sounds alarming, but context matters. Most of these were small, asymptomatic clots in the calf. The clinical significance of small, below-knee DVTs remains debated among specialists.

A systematic review by Hashem et al. (2025) pooled data from 8 studies covering 1,199 Achilles rupture patients and found symptomatic DVT rates ranging from 0.4% to 34% depending on screening method, treatment (surgical vs non-operative), and whether blood thinners were used.

The key point: you almost certainly won’t be screened with ultrasound unless you have symptoms, so knowing the warning signs matters.

Warning Signs You Must Know

DVT Warning Signs (Leg)

• New calf pain that feels different from your Achilles injury — often a deep, cramping ache
• Swelling in one leg only, particularly above the rupture site towards the knee
• Warmth or redness in the calf area
• Heavy or tight feeling in the affected leg

The tricky part: your injured leg will already be swollen and uncomfortable from the rupture itself. What you’re looking for is a change — new pain, increased swelling, or symptoms that don’t match your normal post-rupture discomfort.

PE Warning Signs (Lungs) — Call Emergency Services

• Sudden breathlessness that you can’t explain
• Sharp chest pain, especially when breathing in
• Feeling faint or lightheaded
• Coughing up blood (rare but serious)
• Rapid heartbeat

If you experience any combination of these lung symptoms, call emergency services immediately. Do not wait to see if it passes. A PE is treatable, but only if caught quickly.

Blood Thinners During Recovery

Most hospitals will assess your blood clot risk after an Achilles rupture and prescribe blood thinners (anticoagulants) if appropriate. The clinical positions file recommends 4–6 weeks duration, covering the full equinus (toes-down) phase of recovery, with oral tablets preferred for compliance.

Common Options

Medication	Type	How it’s taken	Typical duration
Enoxaparin / Dalteparin	Low molecular weight heparin (LMWH)	Daily injection (self-administered)	4–6 weeks
Rivaroxaban	Direct oral anticoagulant (DOAC)	Oral tablet	4–6 weeks

Research from Saragas et al. (2017) found that switching from injections to oral rivaroxaban resulted in just 1 DVT event in 28 patients (3.6%) — and that patient admitted to not taking the medication. Oral tablets tend to have better compliance because patients find daily injections difficult to maintain.

Who Gets Blood Thinners?

Not every patient needs them. Your clinician will consider:

• Age (risk increases over 35–40)
• Body weight (BMI over 25–30 increases risk)
• Previous blood clots (personal or family history)
• Whether you had surgery (surgical repair roughly triples the risk compared to non-operative treatment)
• Mobility level (non-weight-bearing carries higher risk than early weight-bearing)
• Other risk factors (smoking, hormonal contraception, cancer, pregnancy)

Some hospitals use a scoring system called the TRiP(cast) score to systematically assess who needs medication and who can manage with movement alone.

No-one really knows the ideal duration for blood thinners after Achilles rupture. The 4–6 week recommendation is based on the best available evidence, but practice varies between hospitals and countries. Follow your clinician’s advice.

What You Can Do to Reduce Your Risk

You can’t eliminate the risk entirely, but you can reduce it:

1. Walk in your boot as much as your protocol allows. Early weight-bearing activates the calf pump. Lee et al. (2023) reported lower VTE rates in patients on early weight-bearing protocols (1.3%) versus non-weight-bearing (2.9%).

2. Take your blood thinners exactly as prescribed. If you’re on injections and struggling, ask your clinician about switching to oral tablets.

3. Stay hydrated. Dehydration thickens the blood and increases clotting risk.

4. Move your toes and ankle within the limits your protocol allows. Even small movements help blood flow.

5. Elevate your leg when resting to assist venous return.

6. Don’t sit or lie still for long periods. If you’re watching TV or working from home, get up and move every hour.

7. Wear your boot (or night splint) as instructed — but don’t use immobilisation as an excuse to stay sedentary.

8. Know the warning signs listed above. Early detection makes all the difference.

Frequently Asked Questions

How common are blood clots after an Achilles rupture?

Very common when actively screened with ultrasound — up to 48% of patients in research studies. Most of these are small, below-knee clots with no symptoms. Symptomatic DVT rates are lower, around 1–9%, depending on whether blood thinners were used and whether the patient had surgery.

Will I be given blood thinners after my Achilles rupture?

It depends on your individual risk. Many hospitals prescribe blood thinners (usually low molecular weight heparin injections or oral tablets like rivaroxaban) for 4–6 weeks during the boot phase. Your clinician will assess factors including your age, weight, clot history, and whether you had surgery. If you haven’t been offered a risk assessment, ask for one.

What are the signs of a blood clot in the leg after Achilles rupture?

Watch for new calf pain that feels different from your Achilles injury, swelling in just one leg (especially above the rupture site towards the knee), warmth or redness in the calf, or a heavy, aching feeling. If in doubt, contact your clinician — an ultrasound scan can confirm or rule out a clot quickly.

Can I get a blood clot even if I’m taking blood thinners?

Yes. Blood thinners significantly reduce the risk but don’t eliminate it. One study found a 34% DVT rate even with dalteparin prophylaxis. Stay alert to the warning signs regardless of whether you’re on medication.

Does walking in the boot help prevent blood clots?

Yes. Early weight-bearing helps activate the calf muscle pump, which pushes blood back up to the heart. Walk as much as your rehabilitation protocol allows.

How long does the blood clot risk last?

The highest risk period is the first 3 months, particularly while you’re immobilised in a boot. The risk drops significantly once you’re walking freely. Blood thinners are typically prescribed for 4–6 weeks — through the full equinus (toes-down) phase of your recovery timeline.

References

1. Barfod KW, Nielsen EG, Olsen BH, et al. Risk of Deep Vein Thrombosis After Acute Achilles Tendon Rupture: A Secondary Analysis of a Randomized Controlled Trial. Orthop J Sports Med. 2020;8(4). PMC
2. Hashem M, Elbeshbeshy M, Khalafallah M, et al. Optimizing Venous Thromboembolism Prophylaxis in Achilles Tendon Rupture: A Systematic Review. Cureus. 2025;17(10):e95184. PMC
3. Nilsson-Helander K, Thurin A, Karlsson J, Eriksson BI. High incidence of deep venous thrombosis after Achilles tendon rupture: a prospective study. Knee Surg Sports Traumatol Arthrosc. 2009;17(10):1234-1238. PubMed
4. Lee C, Haarer F, Titheradge R, Iliopoulos E. Thromboembolic events during weightbearing vs nonweightbearing accelerated rehabilitation protocols for complete Achilles tendon ruptures. Foot Ankle Orthop. 2023;8. PMC
5. Saragas NP, Ferrao PN, Jacobson BF, et al. The benefit of pharmacological venous thromboprophylaxis in foot and ankle surgery. S Afr Med J. 2017;107:327-330. PubMed
6. Calder JDF, Freeman R, Domeij-Arverud E, et al. Meta-analysis and suggested guidelines for prevention of venous thromboembolism (VTE) in foot and ankle surgery. Knee Surg Sports Traumatol Arthrosc. 2016;24(4):1409-1420. PMC