What is the protocol for denatured (deactivated) injections into hypertrophic scars?

Protocol for Intralesional Injections into Hypertrophic Scars

For hypertrophic scars, inject triamcinolone acetonide 40 mg/mL intralesionally, with treatment frequency ranging from once weekly to monthly depending on scar response, avoiding injection into active infections or areas with previous hypersensitivity to triamcinolone. 1

Standard Intralesional Corticosteroid Protocol

Medication and Dosing

• Triamcinolone acetonide 40 mg/mL is the standard concentration for hypertrophic scars 1
• For nodular acne scars (different indication), triamcinolone 10 mg/mL may be diluted to 5 or 3.3 mg/mL with sterile normal saline 1
• The higher concentration (40 mg/mL) is specifically indicated for hypertrophic scars and keloids 1

Injection Technique

• Inject directly into the hypertrophic scar tissue intralesionally 1
• Avoid injecting into healthy surrounding tissue 1
• Mark the borders of the scar with skin-safe single-use markers before treatment 1
• Use appropriate needle gauge (typically 25-27 gauge based on injection principles) 1

Treatment Frequency

• Initial phase: More frequent injections (once to thrice weekly) are more efficacious 2
• Stabilization phase: Decrease frequency to weekly or monthly as the scar responds 2
• Continue treatment until scar stabilization or resolution 2

Expected Response Timeline

• Most hypertrophic scars flatten within 48 to 72 hours after injection 1
• Monitor and record scar evolution at each visit, potentially using photography with patient consent 1

Absolute Contraindications

The following are strict contraindications for intralesional corticosteroid injection 1:

• Active infections at the injection site (impetigo, herpes simplex) 1
• Previous hypersensitivity to triamcinolone 1
• Active tuberculosis or systemic fungal infection (for large injections) 1
• Extensive plaque psoriasis, pustular psoriasis, or erythrodermic psoriasis 1
• Active peptic ulcer disease 1
• Uncontrolled diabetes, heart failure, or severe hypertension 1
• Severe depression or psychosis 1

Combination Therapy Options

Triamcinolone + 5-Fluorouracil (5-FU)

• Combination protocol: Triamcinolone 1 mg/cc mixed with 5-FU 50 mg/cc appears more effective and less painful than either agent alone 2
• High-quality evidence supports intralesional triamcinolone + fluorouracil injections for significant improvements in scar height, pliability, and pigmentation 3
• This combination represents the best-supported option based on systematic review of level 1 evidence 3

Addition of Pulsed Dye Laser

• Simultaneous pulsed dye laser treatments with injection therapy were found most effective in one long-term study 2
• This triple combination (5-FU + triamcinolone + laser) may optimize outcomes 2

Monitoring and Safety

Adverse Effects to Monitor

Local complications from intralesional corticosteroids include 1:

• Atrophy (from local overdose)
• Pigmentary changes
• Telangiectasias
• Hypertrichosis
• Impaired wound healing
• Sterile abscess formation
• Steroid acne
• Contact allergic dermatitis from benzyl alcohol preservative

Systemic Concerns

• Repeated injections can suppress the hypothalamic-pituitary-adrenal axis 1
• Rare anaphylaxis, angioedema, and urticaria 1

Documentation Requirements

• Check injection sites at every regular visit, or at least annually 1
• Record scar evolution using photography (with consent), body maps with size/shape/texture descriptors, or transparent graduated recording sheets 1

Clinical Efficacy Context

Intralesional injection appears to be the best option for hypertrophic scar treatment based on systematic review of high-quality evidence. 3 While many treatment modalities exist (pressure therapy, silicone, topical agents, cryotherapy, laser), intralesional corticosteroid therapy—particularly when combined with 5-FU—has the strongest evidence base from level 1 studies 3, 2.

Important Caveats

• This treatment is efficacious for occasional or particularly stubborn lesions but is not an effective strategy for patients with multiple widespread lesions 1
• Simple surgical excision of hypertrophic scars usually results in recurrence unless adjunct therapies like intralesional injections are employed 4
• Prevention remains the best strategy; patients predisposed to excessive scarring should avoid nonessential surgery 4
• No universally accepted treatment protocol exists despite extensive literature, and treatment selection should consider the specific clinical presentation 4, 5