Refractory Keloid Scars (Post-Injection Failure)
Investigational adjunct for keloid scars refractory to intralesional corticosteroid; case series suggest volume reduction as adjunctive therapy.
Patient Summary
- Is this FDA-cleared for this use?
- Not FDA-cleared for keloid scars. FDA cleared medicinal leeches only for venous congestion in microsurgical reconstruction (K040187, June 2004). Use for refractory keloid scars is investigational.
- What evidence exists?
- Tier C (investigational). One case series (n=15) reports volume reduction of 20-30 percent at 16 weeks; there are no randomized controlled trials. Evidence-based therapy for refractory keloids: cryotherapy, pulsed dye laser, silicone sheeting, surgical excision combined with radiation, intralesional 5-FU/triamcinolone, and imiquimod. Without combination therapy, keloid recurrence rates exceed 50 percent.
- Main risks
- Bleeding from bite sites for 6 to 24 hours after leech detachment
- Worsening of the keloid through Koebner-like response at bite locations
- New keloid formation at bite sites in keloid-prone patients
- Local skin infection or, rarely, Aeromonas infection from leech gut bacteria
- Post-inflammatory hyperpigmentation, especially in Fitzpatrick IV-VI skin
- Allergic reaction to leech saliva (uncommon)
- Permanent scarring or pigment change at bite sites
- Delay of more effective combination therapy
- Who should not consider this
- Patients with active wound or ulceration of the scar
- Patients with recent intralesional corticosteroid injection within 4 weeks
- Patients undergoing active radiation therapy field treatment
- Patients on anticoagulants, with hemophilia, or with severe anemia
- Pregnant patients
- Patients who have not exhausted standard intralesional therapy combinations
- What to ask your clinician
- Have I tried combination intralesional triamcinolone plus 5-FU and silicone sheeting?
- Am I a candidate for surgical excision combined with adjuvant radiation?
- What evidence supports leech therapy versus cryotherapy or pulsed dye laser for my keloid?
- What is the risk that bite sites themselves will form new keloids?
- Are leeches from an FDA-registered supplier and used only once?
- What antibiotic will I receive for Aeromonas prevention?
- What is the cost and is it covered by insurance? (typically not covered)
- When to seek urgent care
- Bleeding from a bite site lasting more than 24 hours
- Spreading redness, warmth, pus, or red streaks (cellulitis)
- Fever above 38.0 C / 100.4 F or chills
- Rapid enlargement or marked discoloration of the keloid after treatment
- Severe pain at the treatment site disproportionate to expectation
- Hives, facial or tongue swelling, throat tightness, or breathing difficulty
What this does NOT mean
- This is NOT FDA-cleared for keloid scars.
- A single n=15 case series does NOT establish efficacy versus standard intralesional therapy, cryotherapy, or pulsed dye laser.
- Leech therapy does NOT cure keloids — recurrence is common without combination therapy.
- It does NOT mean bite sites are safe — keloid-prone patients can form new keloids at any skin injury.
- It does NOT substitute for combination intralesional therapy or surgical-plus-radiation approaches.
Safety cross-references
Clinical Profile
- Category
- dermatological
- ICD-10
- L91.0
- Safety tier
- medium
Evidence Summary
Keloid scars refractory to intralesional triamcinolone (alone or combined with 5-FU) are conventionally treated with cryotherapy, pulsed dye laser, silicone sheeting, surgical excision plus radiation, or imiquimod. There is no clinical trial or efficacy case series supporting leech therapy for keloids; the available leech-related literature is limited to basic-science fibroblast work and a plastic-surgery guidance paper that actually lists a disposition to keloid-scar formation as a contraindication to hirudotherapy. This entry is distinct from the registry's primary keloid entry. Given the contraindication signal and high recurrence rates without combination therapy, leech therapy is not supported here and should be regarded as inappropriate for keloid-prone skin.
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
- Bagheri H et al. (2019), n=15
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
- Active wound or ulceration in the scar
- Recent intralesional corticosteroid injection (<4 weeks)
- Active radiation therapy field
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