What is the efficacy of allantoin and onion bulb extract on scars?

Efficacy of Allantoin and Onion Bulb Extract on Scars

Microneedling combined with platelet-rich fibrin (PRF) or platelet-rich plasma (PRP) is significantly more effective for scar treatment than products containing allantoin and onion extract, which show only modest efficacy for hypertrophic scars and minimal benefit for atrophic scars. 1

Mechanism of Action

Allantoin and onion bulb extract products (such as Contractubex) work through several mechanisms:

• Onion extract contains quercetin and kaempferol which have anti-inflammatory properties
• Allantoin promotes cell proliferation and wound healing
• When combined with heparin (as in Contractubex), they may help reduce collagen production in hypertrophic scars

Efficacy by Scar Type

Hypertrophic Scars

• Silicone-based products demonstrate superior efficacy compared to onion extract with allantoin 2
• In a comparative study, both silicone gel and silicone sheets showed statistically significant improvement over Contractubex (onion extract with allantoin and heparin) for hypertrophic scars 2
• However, onion extract products do show some efficacy:
  • A 2020 study of overnight intensive patches containing onion extract and allantoin showed:
    • 28.8% decrease in scar height
    • 31.9% reduction in scar volume
    • Reduction in pain and pruritus 3

New Scars (Prophylactic Use)

• A randomized controlled trial showed that proprietary onion extract gel significantly improved the appearance of new scars after 4-8 weeks of application compared to no treatment 4
• For post-cesarean section scars, prophylactic use of gel containing onion extract, allantoin, and heparin effectively reduced scarring in terms of vascularity, pigmentation, and height 5

Atrophic Scars

• Limited evidence supports the use of allantoin and onion extract for atrophic scars
• For atrophic scars (including acne scars), current guidelines strongly recommend:
  • Microneedling combined with PRF or PRP (75% satisfaction rate)
  • This combination shows 3-fold better therapeutic response than other treatments 1

Treatment Protocol

For optimal results when using onion extract and allantoin products:

1. Duration: Treatment should be continued for at least 3-6 months for visible effects 3
2. Application: Once daily application is recommended 4
3. Timing: Early intervention is crucial - start treatment as soon as wound healing occurs 1

Comparative Efficacy

When comparing treatment options for scars:

1. First-line treatments for hypertrophic scars:

   • Silicone-based products (gel or sheets)
   • Tension reduction
   • Wound edge eversion 6

2. Second-line treatments:

   • Onion extract with allantoin (modest efficacy)
   • Pressure garments
   • Scar massage 6

3. For atrophic scars:

   • Microneedling with PRF or PRP (highest efficacy)
   • Laser therapy (pulsed-dye or CO2)
   • Corticosteroids for specific cases 1

Clinical Considerations

• Patient adherence is critical for success with any scar treatment
• Realistic expectations should be set - complete scar resolution is often not achievable
• Multiple treatment sessions are typically required
• Scar maturity affects treatment response - immature scars often respond better to treatment 1
• For resistant cases, combination therapy may be necessary

Conclusion

While products containing allantoin and onion extract show some efficacy for hypertrophic and new scars, they are less effective than silicone-based products and significantly less effective than microneedling with PRF/PRP for atrophic scars. For optimal outcomes, treatment should be continued for at least 3-6 months with consistent daily application.