Keloid injection prescription
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Keloid Intralesional Injection - Prescription Guide
First-Line Agent: Triamcinolone Acetonide (TA)
Standard Prescription
Drug: Triamcinolone acetonide suspension (Kenalog)
| Parameter | Detail |
|---|---|
| Concentration | Start: 10 mg/mL; increase to 20-40 mg/mL if needed |
| Dilution | Dilute 1:3 with normal saline or 1% lidocaine (single-dose vials) → gives 2.5 mg/mL starting solution |
| Syringe | 1 mL tuberculin Luer-Lok syringe |
| Needle | 27- or 30-gauge needle |
| Technique | Inject intralesionally (into the substance of the scar), bevel down; advance through the lesion while injecting; keep injection within the lesion margins |
| Endpoint | Scar should blanch slightly during injection |
| Frequency | Every 4-8 weeks (typically every 6 weeks) |
| Duration | Repeat as needed; reassess after 3-6 sessions |
Locked (Luer-Lok) syringes are preferred to prevent needle disengagement under high injection pressure in dense keloids.
Concentration Titration
- Small, soft, or early keloids: Dilute to 2.5 mg/mL (1:3 dilution with saline or 1% lidocaine)
- Moderate/refractory keloids: 10 mg/mL undiluted or 1:2 with lidocaine
- Dense/old keloids: 40 mg/mL undiluted (Kenalog-40)
- Fitzpatrick's Dermatology recommends starting at 10 mg/mL and titrating up to 40 mg/mL as needed
A common error is being too aggressive too early - go slowly to avoid atrophy.
Pre-injection: Anesthesia
- Inject 1% lidocaine around (not into) the lesion using a 27-31 gauge needle before the TA injection
- Alternatively, mix 1% lidocaine directly into the TA solution for patient comfort
Optional: Cryotherapy Pre-treatment
Before the TA injection, apply liquid nitrogen spray for a 3-5 second burst to the keloid:
- Creates tissue edema, softening the lesion
- Allows better steroid dispersal and penetration
- Reduces injection pressure needed and decreases pain
- Wait 20-60 minutes for edema to develop before injecting
Combination Regimens (for Refractory/Large Keloids)
TA + 5-Fluorouracil (5-FU)
A 2024 meta-analysis (PMID 37337341) showed combination TA + 5-FU is superior to either agent alone.
| Agent | Dose | Notes |
|---|---|---|
| Triamcinolone acetonide | 10-40 mg/mL | As above |
| 5-Fluorouracil | 50 mg/mL | Mix with TA; typical ratio 9:1 (5-FU:TA) |
- 5-FU mechanism: inhibits fibroblast proliferation by blocking DNA synthesis; decreases TGF-β-induced collagen type I expression
- Response rate: up to 95% with 5-FU alone; 75%+ reduction in 40% of cases
- Side effects of 5-FU: pain, hyperpigmentation, ulceration (less frequent with combination)
TA + Verapamil
- Verapamil (calcium channel blocker) decreases IL-6, VEGF, and inhibits keloid fibroblast growth
- Used as an alternative combination agent
Triple Therapy: 5-FU + TA + Pulsed Dye Laser (PDL)
- Average flattening ~79% with maximal triple therapy vs ~50% with TA monotherapy
- PDL sessions coordinated with injection visits
Perioperative Protocol (Post-excision Prophylaxis)
For surgically excised keloids, to prevent recurrence:
- 3 months before surgery: TA injection 2.5-5.0 mg/mL into the keloid-normal skin interface
- 6 weeks before surgery: Repeat TA injection
- Day of surgery: TA mixed with local anesthetic at time of excision
- 4 weeks post-op: Follow-up, inject early if recurrence signs appear
- 8 weeks post-op: Follow-up; continue injections every 3 months for 1-2 years
Post-excision recurrence rate with steroid injection is significantly lower than excision alone (which has >50% recurrence).
Other Intralesional Agents
| Agent | Notes |
|---|---|
| Bleomycin | 66-84% show >75% flattening; risk of hyperpigmentation (esp. darker skin) and local atrophy; no systemic toxicity at keloid doses |
| Interferon-α2b | Less evidence; not clearly superior to TA post-excision |
| Etanercept | Intralesional; some efficacy shown |
Side Effects to Counsel
- Hypopigmentation - most common; often improves over time; reduced by lower concentrations and dilution
- Perilesional skin atrophy
- Perilymphatic linear atrophy (spread along lymphatics from injection site)
- Telangiectasia
- Hyperpigmentation (more with 5-FU)
- Systemic corticosteroid effects - rare; possible with repeated high-dose injections
Key Points
- Intralesional TA flattens and softens keloids and stops itching reliably, but does not narrow the scar - width is not reduced
- Young, small keloids respond better than old, large ones
- Keloids >1-1.5 cm diameter generally resolve more slowly and incompletely
- Hyperpigmentation typically persists even with successful treatment
- Silicone gel sheeting can be used adjunctively between injection sessions
Sources: Andrews' Diseases of the Skin (Clinical Dermatology), p. 449 | Pfenninger and Fowler's Procedures for Primary Care, p. 278 | Fitzpatrick's Dermatology, p. 1138 | Cummings Otolaryngology, p. 3965
Recent evidence (PMID 41860092 - 2026 network meta-analysis) continues to support combination intralesional therapies as superior to TA monotherapy for keloid treatment.
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