Mederma Advanced Scar Gel
The best-known over-the-counter scar treatment in the US. Widely available, affordable, and mechanistically different from silicone — but the evidence is modest at best.
Current listing on Amazon Associates. Price and availability change — confirm on the product page.
Last verified: 2026-04-24
Overview
Mederma Advanced Scar Gel is the flagship product from the Mederma line, built around Cepalin (an onion bulb extract, Allium cepa) combined with allantoin and other emollients. It's been on the market for decades and is the highest-volume scar product in US pharmacies. Most people starting scar research try Mederma first, often before they've heard of silicone.
The mechanism is separate from silicone: the onion extract is proposed to have anti-inflammatory and fibroblast-modulating effects, while allantoin softens the stratum corneum. Unlike silicone, Mederma doesn't occlude the scar or trap moisture — it absorbs in as a leave-on cosmetic gel.
We list Mederma because people ask about it constantly and it's worth giving an honest answer. For minor flat scars and redness, daily Mederma for several months can produce modest cosmetic improvement. For hypertrophic scars and keloids, the evidence base is much weaker than silicone, and we'd recommend silicone first in almost every case.
Research and evidence
Published trials on onion extract for scar management show mixed and often modest results. Several comparative studies have found silicone gels outperforming Mederma on thickness and pliability endpoints, though Mederma sometimes shows improvements on redness and cosmetic appearance versus placebo. Dermatology consensus guidelines for keloid and hypertrophic scar management consistently rank silicone as first-line and onion extract products as adjunct or optional.
Pros and cons
Pros
- • Widely available, low-cost entry point to scar care
- • Onion extract (Cepalin) and allantoin formulation with decades of consumer use
- • Non-greasy gel, easy to apply under clothing and makeup
Cons
- • Clinical evidence is mixed — several studies show modest or no benefit vs. vehicle
- • Silicone-based products have stronger research backing for keloids and hypertrophic scars
- • Requires 3-6 months of daily use to see any effect
Best for
- • Minor flat scars and discoloration where cosmetic appearance is the goal
- • Users who can't tolerate silicone sheets or gels for adherence reasons
- • Early-stage scars as a low-cost trial before stepping up to silicone
How to use it
- 1Start once the wound has fully closed — not on open or weeping scars.
- 2Apply a pea-sized amount to the scar and massage in until fully absorbed.
- 3Use three to four times daily on new scars (under 2 months old).
- 4Use once daily for the newer once-daily formulation — check the product label you receive.
- 5Continue for a minimum of 8 weeks on new scars and 3-6 months on older scars.
- 6Avoid layering Mederma and silicone at the same time — silicone needs a clean, cream-free surface. Pick one.
Alternatives to consider
Choose this when: You're dealing with a hypertrophic scar, keloid, or any raised or thickened scar. Silicone has substantially stronger evidence and should be the first choice.
Choose this when: You want a leave-on gel format but with better evidence — Kelo-cote is silicone-based and gives you the wearability of a gel with the mechanism of medical silicone.
Frequently asked questions
Is Mederma as good as silicone sheets or silicone gel for keloids?
No. For keloids and hypertrophic scars specifically, silicone-based products have significantly stronger clinical evidence. Mederma may help with flat scar appearance and redness, but it's not the right primary treatment for raised scars.
How long does Mederma take to work?
Expect a minimum of 8 weeks on newer scars and 3-6 months on older scars before judging results. Inconsistent daily use is the most common reason people feel it isn't working.
Can I use Mederma on old scars?
You can, and it's one of the scenarios where Mederma performs best relative to its strong claim — cosmetic improvement on flat, pigmented older scars. But improvements are typically modest and cumulative over months of daily use.
Are there side effects?
Most users tolerate it well. The most common reaction is mild contact irritation or burning, which usually resolves on discontinuation. Stop use if a rash develops.
Sources
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Medical disclaimer
ScarInsight provides educational information about scar and keloid treatments based on published research. This content is not intended to diagnose, treat, or prevent any medical condition. Individual results vary. Treatment decisions should be made in consultation with a qualified dermatologist or healthcare provider who can evaluate your specific situation. ScarInsight is not a healthcare provider and does not offer medical advice.
Last reviewed: 2026-04-24