Burn scars can sometimes heal in a way that causes them to become thick, raised, and stiff. These scars may itch, feel uncomfortable, limit movement, and affect how the skin looks. Because of this, many burn survivors look for treatments that can help improve both the appearance and the symptoms of their scars.

One treatment that has shown promise is fractional CO₂ laser therapy. This laser creates tiny openings in the scar tissue that help soften the scar and stimulate the skin to remodel itself. These openings can also help medications applied to the skin reach deeper into the scar where they may work better.

A steroid medication called triamcinolone is commonly used to treat these scars. Another medication, called 5-fluorouracil (5-FU), has been shown in prior studies to work well when combined with steroids, but it is usually given by injection, which can be painful and sometimes causes side effects.

In this study, we will look at whether delivering these medications through the laser openings can improve scars more effectively. Each participant's scar will be divided into two halves. One side will receive both medications, and the other side will receive the steroid alone. By comparing the two sides of the same scar, we hope to better understand whether adding 5-FU provides additional benefit.

Inclusion Criteria:

• Patient with hypertrophic scarring secondary to burn injury
• Ages 18-89

Exclusion Criteria:

• Pregnant patients or patients of childbearing age, sexually active, and unwilling to utilize contraception
• Children
• Individuals that are cognitively impaired and unable to provide consent
• Currently breastfeeding
• Has taken oral retinoids within 6 months of study initiation
• Prior laser or intralesional TAC/5-FU treatments for their hypertrophic scars
• Active infection
• Active malignancy
• Known hypersensitivity to CO2 laser, TAC, or 5-FU
• Known dihydropyrimidine dehydrogenase (DPD) deficiency (complete or partial), due to risk of systemic 5-FU toxicity
• Systemic corticosteroid or immunosuppressive medication use
• Intolerance to anesthesia
• Known connective tissue disease

Individual participant data will not be shared. Deidentified aggregate results will be reported in future publications and presentations; however, participant-level data will not be made available due to privacy considerations, the potential identifiability of scar images and clinical characteristics, and limitations of the current IRB-approved protocol.

Participants, treating clinicians, and outcome assessors will be masked to treatment allocation. Study medications will be prepared and labeled in a manner that does not reveal group assignment. Treatment segments will be identified using coded allocation records, and outcome assessments will be performed using standardized evaluations without disclosure of the assigned treatment condition.