What is the onset and duration of action of Kenalog (triamcinolone) after intralesional injection into a scar?

Onset and Duration of Action of Kenalog (Triamcinolone) in Scar Treatment

Intralesional triamcinolone acetonide (Kenalog) begins to work within 3 days of injection into a scar, with more significant effects observed by 7 days, and typically requires 3-4 weeks between treatments for optimal results. 1, 2

Mechanism of Action and Timeline

• Initial effects (3 days):

  • Triamcinolone begins inhibiting both type I and type III procollagen mRNA expression within 3 days of injection 2
  • Anti-inflammatory effects begin to reduce scar inflammation

• Early visible effects (7 days):

  • By day 7, type I collagen proteins are significantly reduced (p < 0.05) 2
  • Type III collagen proteins show some reduction, though not statistically significant at this timepoint 2
  • Procollagen mRNA expression continues to decrease further by day 7 2

• Full therapeutic effect:

  • The American Academy of Dermatology recommends treatments every 3-4 weeks until the keloid flattens 1
  • Complete flattening typically requires 4-6 treatment sessions 1

Dosing and Administration

• Standard concentration: 40 mg/mL for most keloid treatments 1
• Reduced concentration: 10-20 mg/mL for facial or thin-skinned areas to minimize atrophy risk 1
• Treatment interval: Every 3-4 weeks until desired flattening is achieved 1
• Maximum sessions: Typically 4-6 sessions are needed for optimal results 1

Factors Affecting Response Time

1. Scar characteristics:

   • Newer scars typically respond faster than older, more established ones
   • Thinner scars generally show more rapid improvement than thicker ones

2. Treatment combinations:

   • Combining triamcinolone with other agents may accelerate response
   • TAC combined with 5-fluorouracil (5-FU) shows faster and more effective results than TAC alone 3
   • Adding pulsed dye laser treatments simultaneously with injections appears to be most effective 4

3. Injection frequency:

   • More frequent initial injections (once to thrice weekly) followed by decreasing frequency (weekly to monthly) during stabilization may be more efficacious 4

Common Pitfalls and Considerations

• Avoid overtreatment: Using too high a concentration (especially in facial areas) can lead to atrophy and pigmentary changes 1
• Monitor for side effects: Fat/dermal atrophy, pigmentary changes, and folliculitis are possible complications 1
• Manage expectations: Inform patients that multiple treatments are typically required, with full results not immediate
• Consider adjunctive therapy: For resistant scars, combining triamcinolone with 5-FU or laser therapy may provide superior outcomes 4, 3

For optimal results, patients should be evaluated at 3-4 week intervals to assess response and determine the need for additional treatments, with most patients requiring multiple sessions to achieve maximal scar flattening.