What Works
Ultrasound scan of both legs High
Not a treatment, but it outranks every treatment because it decides all of them. It is the step that finds the 18.1% who already have a deep vein clot (95% CI 13.9 to 23.3) and the 6.9% who already have one in the lung (95% CI 3.9 to 11.8). Both legs, not just the sore one.
Expected timeline: within days of noticing it, sooner with any red flag below.
Fondaparinux 2.5 mg daily for 45 days High
For a clot at least 5 cm long and at least 3 cm away from the groin junction. It cut the combined rate of death, clot in the lung, deep vein clot, extension to the junction or recurrence from 5.9% to 0.9%, a relative reduction of 85% (95% CI 74 to 92), p<0.001. Clot in the lung or deep veins alone fell from 1.3% to 0.2%.
The honest other side of that number: 88 people need treating to prevent one lung or deep vein clot, because the underlying risk is low to begin with. Major bleeding happened to one patient in each group of roughly 1,500.
This is a prescription. It is not something a physical therapist can provide, and it is the only thing in this list shown to reduce the outcome that matters.
Tier 2 and Tier 3 options
Rivaroxaban 10 mg daily for 45 days Moderate
The tablet alternative where an injection is unacceptable. Non-inferior to fondaparinux, 3% against 2%. Read the caveat with the result: the trial was open-label, it turned on 11 events in total, and its non-inferiority margin was 4.5% absolute against an event rate of 2 to 3%. It has never been shown better than placebo in an adequately sized trial, because the placebo-controlled attempt stopped at 85 of 600 planned patients.
Direct oral anticoagulants, on safety grounds Moderate
65% less major or clinically relevant bleeding than fondaparinux or heparin (RR 0.35, 95% CI 0.15 to 0.83), with no statistical heterogeneity between studies. The review's authors rate the safety evidence high certainty and the efficacy evidence moderate.
Therapeutic or intermediate-dose low molecular weight heparin Moderate
Reduces the clot spreading and coming back. Does not reduce deep vein clots or lung clots, and the apparent benefit in older trials had disappeared by three months. In real-world follow-up it performed worst of the three drug classes, 22.4% at 12 months against fondaparinux's 10.4%.
Keep walking, avoid bed rest Opinion
The single retrieved source on activity is an expert opinion document that advises against bed rest and reduced mobility. It fits the mechanism, since sluggish blood flow is part of what causes clots, and nothing contradicts it. No trial has tested it, and none ever will, because no one would randomise patients to bed rest. It should be labelled opinion permanently rather than provisionally.
Topical anti-inflammatory or heparinoid Opinion
Reported to control local symptoms and shorten how long the redness lasts. Symptom relief only, with no shown effect on the clot spreading or travelling.
Exercise Prescription
An honest note before the table. No study has ever tested an exercise, a number of sets, a number of repetitions, or an amount of walking in this condition. Every number below is marked consensus because that is exactly what it is: sensible practice, not a proven dose. Nobody has shown that doing these changes the course of your clot. They exist to keep you moving, because staying still is part of what causes clots in the first place.
| Movement | How | Dose | Frequency | Guide |
|---|---|---|---|---|
| Walking | Normal walking on the flat at a comfortable pace. This is the main one | 10 to 20 min consensus | 3 to 4× daily consensus | Mild ache over the sore vein is expected. Stop if the whole leg swells |
| Ankle pumps | Sitting or lying, point the toes away then pull them back | 2 × 20 consensus | Every hour of sitting consensus | Should not hurt at all |
| Calf raises | Stand holding a worktop, rise onto the toes, lower slowly | 2 × 15 consensus | Twice daily consensus | Mild effort, not sharp pain over the vein |
| Leg elevation | Lie down with the leg supported above hip height | 15 min consensus | 2 to 3× daily consensus | Eases aching. Relieves symptoms, does not treat the clot |
Your treating clinicians' instructions override this table. It is mobility, not rehabilitation, because this condition's actual treatment is a prescription and a scan.
What Doesn't Work
- Compression stockings for stopping the clot spreading. This is the one intervention a physical therapist owns, and the only randomised comparison that tested it found significantly more clot extension in the compression-only group (p<0.05), with no difference in deep vein clots at three months. That trial is from 1999, it tested compression as the sole treatment rather than alongside medication, and it excluded obesity, cancer, heart disease and everyone over 70, so it does not establish harm. What it does remove is any basis for claiming a stocking stops this clot spreading. Wear one for comfort and for the varicose veins underneath, once someone has checked the pulses in your foot, and be clear that the medication is doing the actual work.
- Reassurance and discharge without a scan. The commonest failure in this condition, and the one that misses an 18.1% concurrent deep vein clot rate.
- Treating one normal scan as the end of it. Six of 20 extensions into the deep system were found only on a second scan, not the first.
- Bed rest. No evidence supports it, and sluggish blood flow is the mechanism that caused the problem.
- Surgery to prevent a clot travelling. In real-world comparison, serious clot events occurred in 6.3% of surgically treated against 5.8% of conservatively treated patients, recurrence in 5.3% against 4.7%, and bleeding in 2.1% against 1.4%. Every difference was non-significant. Surgery here treats the varicose veins that caused the clot, timed after the acute episode, not the clot itself.
- Deep tissue work, vigorous massage or manipulation over an acute clot. No evidence exists in either direction and no plausible benefit does either. This is a reasoning position rather than a trial finding, and it is labelled as one.
