Within-Patient, Quasi-Experimental Clinical Trial to Assess the Immediate Effects of Paraffin Wax on Adult, Post-Burn Hypertrophic Scar

Paraffin wax is applied to scar tissue for its proposed benefits of increasing skin pliability and relieving pain. However, limited studies have objectively assessed hypertrophic scar (HSc) response. This study examined immediate HSc changes after paraffin treatment compared with intra-individual controls. A quasi-experimental, within-subject, evaluator-blinded, pre-post design was used. Two homogeneous HSc were identified per participant: one treated with paraffin wax and one with mineral oil for 20 minutes. Normal skin also received paraffin to assess scar-specific effects. Objective measures included elasticity (Cutometer), erythema and melanin (Mexameter), transepidermal water loss (TEWL) (Tewameter), thickness (High-frequency Ultrasound), and self-reported pain, itch, stiffness, and overall scar impression. Thirty-nine burn survivors were recruited; 35 completed the study. Paired t-tests showed increased elasticity and erythema in paraffin-treated HSc and normal skin, decreased pigmentation in paraffin-treated normal skin, and decreased TEWL in the mineral oil-treated control scars. ANCOVA of post-treatment values, controlling for baseline, revealed significant increases in erythema and TEWL in paraffin-treated versus control scars. Participants perceived greater improvement in paraffin-treated HSc than controls, though controls improved across all items. Although paraffin significantly increased elasticity in both HSc and normal skin, it did not significantly differ from mineral oil-treated scars, suggesting that some of theeffect may be attributable to mineral oil, as there was a slight increase in skin elasticity within the mineral oil group. However, paraffin improved self-reported outcomes, highlighting its potential clinical value in relieving pain and itch rather than increasing scar elasticity. As mineral oil also improved self-reported items, its benefits need further investigation. Future studies should recruit participants with baseline pain and itch to ensure adequate power.