Knee Osteoarthritis
Off-label use; several small RCTs in knee OA report pain and function improvement with leeches versus NSAID gel, sham leech or TENS, though results against sham and TENS are mixed, and a 2022 trial against physiotherapy found no therapeutic effect.
Patient Summary
- Is this FDA-cleared for this use?
- No — investigated off-label. The FDA cleared medicinal leeches in 2004 only for venous congestion in microsurgical reconstruction (K040187). Use for knee osteoarthritis is supported by published research but not FDA-evaluated.
- What evidence exists?
- Several published randomized trials (Michalsen 2003, Stange 2012, Andereya 2008, İşık 2017) and a 2014 meta-analysis (Lauche et al.) suggest a short-term reduction in knee pain compared with a topical NSAID gel, TENS, or a sham leech, although the İşık 2017 trial found leeches about as effective as TENS and a 2022 trial (Talebi, 98 patients) found no benefit and better results with physiotherapy. Effects have been measured out to about 3 to 6 months. The trials are mostly from research groups in Germany, all are small (under 130 patients), and longer-term outcomes (12+ months) are not well studied. This is not a substitute for proven treatments such as exercise therapy, weight management, or surgery when indicated.
- Main risks
- Bleeding and oozing from each bite site for several hours, sometimes up to 24 hours
- Itching, redness, and irritation at the bite sites lasting days to weeks (15 to 20 percent of patients)
- Mild anemia if many leeches are used (uncommon with a single session)
- Local skin infection or, rarely, Aeromonas infection from leech gut bacteria
- Allergic reaction to leech saliva (uncommon)
- Small permanent scars at the bite sites
- Who should not consider this
- Patients taking blood thinners such as warfarin, apixaban, rivaroxaban, dabigatran, or heparin
- Patients with hemophilia or other inherited bleeding disorders
- Patients with severe anemia (hemoglobin under 10 g/dL)
- Patients with a weakened immune system, especially severe neutropenia
- Patients with an active joint infection (septic arthritis) or skin infection at the planned bite area
- Patients within 6 months of a knee replacement surgery
- Pregnant patients (relative caution, especially first and third trimester)
- What to ask your clinician
- Have I tried first-line treatments such as exercise therapy, weight loss, and topical or oral pain medicines, and what does my orthopedist think?
- What is the realistic chance leech therapy will help me, and for how long?
- What evidence does the practitioner rely on, and have they treated patients like me before?
- Are leeches from an FDA-registered supplier and used only once?
- What antibiotic, if any, will I be given for Aeromonas prevention?
- What is the cost and is it covered by insurance? (typically not covered as it is off-label)
- What is the plan if symptoms come back — repeat session, escalation to injections, or surgery referral?
- When to seek urgent care
- Bleeding from a bite site lasting more than 24 hours or soaking through dressings
- Spreading redness, warmth, pus, red streaks, or increasing pain around the bite sites
- Fever above 38.0 C / 100.4 F or chills
- Sudden severe knee pain, swelling, or inability to bear weight
- Hives, facial or tongue swelling, throat tightness, or breathing difficulty
What this does NOT mean
- It does not mean leech therapy is FDA-cleared for knee osteoarthritis — it is not.
- It does not mean leeches cure osteoarthritis — the underlying cartilage wear continues; treatment may only reduce symptoms temporarily.
- It does not mean leech therapy is better than exercise therapy, weight management, physiotherapy, or surgery for appropriate candidates — those remain the standards.
- It does not mean every patient improves — most trials show improvement on average, but one found none, and individual responses vary widely.
- It does not mean a single session is enough forever — the controlled trials followed patients for no longer than about 6 months.
Safety cross-references
Clinical Profile
- Category
- Musculoskeletal
- ICD-10
- M17.0, M17.10, M17.11, M17.12, M17.5
- Safety tier
- Low
Evidence Summary
Randomized trials of leech therapy in knee OA are mostly positive but small, short-term and heterogeneous, and one is negative. Michalsen 2003 (n=51) showed WOMAC pain reduction of ~64% at day 7 vs. ~18% for topical diclofenac (P<0.001); the pain difference was no longer significant after day 7, but function, stiffness and total-symptom scores stayed better with leeches through day 91. Stange 2012 (n=52, unblinded crossover) found leeches superior to TENS in the first period (days 0-21); Andereya 2008 (n=113, blinded, with an artificial-leech control) found improvement in all three groups, significant throughout the 26-week follow-up only in the two leech groups, and could not separate a specific effect from placebo; İşık 2017 (n=90) found leeches about as effective as TENS; and Talebi 2022 (n=98, leeches vs physiotherapy) found no therapeutic effect of leeches, with physiotherapy performing better at 90 days. A 2014 systematic review and meta-analysis (Lauche et al., Clin J Pain; 3 RCTs + 1 controlled trial, 237 patients) found strong evidence for immediate pain reduction (SMD -1.05, P<0.01) and moderate evidence for long-term pain effects (SMD -0.45); a 2018 meta-analysis of 4 RCTs (Wang et al., 264 patients) also favoured leeches at 1 to 7 weeks, rated the evidence quality moderate, and reported more adverse events with leeches. Lauche et al. found no serious adverse events, whereas Wang et al. reported a higher overall incidence of adverse events with leeches. Controlled trials followed patients for up to about 6 months; the only 12-month data identified come from a retrospective series of 24 patients with mixed arthritic joints (Loeser 2020).
Treatment specifics
How many leeches, where they are placed, how long a session lasts, and whether to repeat are clinical decisions made by a qualified provider under institutional protocol — not something to self-administer. Discuss the specifics with a clinician experienced in medicinal leech therapy. (Clinicians: switch the audience selector in the top bar to “Clinician” to view protocol detail.)
Key Trials
- Michalsen A et al. (2003), n=51 · Ann Intern Med · PMID 14597456 · ASH analysis →
- Stange R et al. (2012), n=52 · Complement Ther Med · PMID 22305242 · ASH analysis →
- Lauche R et al. (2014), n=237 · Clin J Pain · PMID 23446069 · ASH analysis →
- Michalsen A et al. 200351
- Stange R et al. 201252
- Lauche R et al. 2014237
- RCT: 2 (67%)
- Meta Analysis: 1 (33%)
Detailed Trial Entries
10 trials indexed in the ASH RCT Library with full Study Profile, GRADE rating, and clinical implications:
- Effectiveness of leech therapy in osteoarthritis of the knee: a randomized, controlled trial
Michalsen A, Klotz S, Lüdtke R, Moebus S, Spahn G, Dobos GJ (2003) · Annals of Internal Medicine · n=51 · GRADE moderate
- Leech therapy for symptomatic treatment of knee osteoarthritis: results and implications of a pilot study
Michalsen A, Moebus S, Spahn G, Esch T, Langhorst J, Dobos GJ (2002) · Alternative Therapies in Health and Medicine · n=16 · GRADE very-low
- Effectiveness of topical gel of medical leech (Hirudo medicinalis) saliva extract on patients with knee osteoarthritis: a randomized clinical trial
Shakouri A, Adljouy N, Balkani S, Mohamadi M, Hamishehkar H, Abdolalizadeh J, Kazem Shakouri S (2017) · Complementary Therapies in Clinical Practice · n=60 · GRADE very-low
- Randomised controlled trial with medical leeches for osteoarthritis of the knee
Stange R, Moser C, Hopfenmueller W, Mansmann U, Buehring M, Uehleke B (2012) · Complementary Therapies in Medicine · n=52 · GRADE low
- Efficacy of leech therapy in the management of osteoarthritis (Sandhivata)
Rai PK, Singh AK, Singh OP, Rai NP, Dwivedi AK (2011) · Ayu · n=25 · GRADE very-low
- Assessment of leech therapy for knee osteoarthritis: a randomized study
Andereya S, Stanzel S, Maus U, Mueller-Rath R, Mumme T, Siebert CH, Stock F, Schneider U (2008) · Acta Orthopaedica · n=113 · GRADE moderate
- A systematic review and meta-analysis of medical leech therapy for osteoarthritis of the knee
Lauche R, Cramer H, Langhorst J, Dobos G (2014) · The Clinical Journal of Pain · n=237 · GRADE moderate
- The efficacy and safety of medical leech therapy for osteoarthritis of the knee: A meta-analysis of randomized controlled trials
Wang H, Zhang J, Chen L (2018) · International Journal of Surgery · n=264 · GRADE moderate
- Controversy: hirudotherapy (leech therapy) as an alternative treatment for osteoarthritis
Gunawan F, Wibowo YR, Bunawan NC, Turner JH (2015) · Acta Medica Indonesiana · n=0 · GRADE very-low
- Comparison of the effectiveness of medicinal leech and TENS therapy in the treatment of primary osteoarthritis of the knee: a randomized controlled trial
Isik M, Ugur M, Yakisan RS, Sari T, Yilmaz N (2017) · Zeitschrift für Rheumatologie · n=90 · GRADE low
Contraindications
- Active anticoagulant therapy (warfarin INR >2.0, DOACs, heparin)
- Hemophilia or other bleeding disorder
- Severe anemia (Hb <10 g/dL)
- Active bacteremia or sepsis
- Known hypersensitivity to leech salivary proteins
- Pregnancy (relative — first/third trimester)
- Immunocompromised state with severe neutropenia
- Acute septic arthritis
- Knee replacement (within 6 months)
Related Conditions
Thumb Carpometacarpal (CMC-1) Osteoarthritis
Off-label use with one small RCT (Michalsen 2008, 32 women) in which single-session leech therapy reduced pain and improved hand function more than topical diclofenac for about 2 months.
Lateral Epicondylitis (Tennis Elbow)
Off-label use with one small RCT (Bäcker 2011, n=40) in which a single leech session reduced pain more than topical diclofenac at day 7; the pain difference was no longer significant at day 45.
Plantar Fasciitis
Investigational use; no clinical study of leech therapy for plantar fasciitis was identified, and the rationale is mechanistic only.
Fibromyalgia
Investigational use only: no clinical study of leech therapy for fibromyalgia was identified, and it is not a primary treatment.