Allantoin, Onion Extract (Cepalin) vs Silicone: Which Works Best?

Core Education: Scar Biology, Types, and How Scars Form

A scar is your skin’s “patch job” after an injury, procedure, burn, or inflammation like acne. When skin is cut or damaged, your body lays down new collagen to close the gap. Collagen is a structural protein, sort of like scaffolding. The catch is that scar collagen is organized differently than uninjured skin, which is why scars can look raised, shiny, tight, or discolored.

Scar formation follows a fairly predictable timeline, even though your results are individual:

• Inflammatory phase (0–7 days): your body stops bleeding and starts signaling repair. Swelling, warmth, tenderness, and early redness are common.
• Proliferation phase (7–21 days): new tissue fills in. Blood vessels increase, which is why scars often look pink or red.
• Remodeling phase (21 days–2 years): collagen reorganizes. Scars usually flatten, soften, and fade gradually.
• Scar maturation (about 6–24 months): the scar reaches its most stable look and feel.

What most patients overlook is that a scar is not “finished” when the skin looks closed. The visible line is just the surface. Underneath, collagen is still being deposited and remodeled for many months.

Common scar types you might be treating

Surgical scars vary based on incision direction, tension on the wound, how the wound was closed, and genetics. Even a beautifully closed incision can become red or thick while it remodels.

Hypertrophic scars are raised, red, and thick but stay within the original wound edges. They are common after surgery, trauma, and burns, especially when there is tension or delayed healing.

Keloid scars are also raised, but they grow beyond the wound borders. They are more common in people with a personal or family history of keloids and in darker skin tones. Keloids often need medical treatments like steroid injections in addition to topical care.

Atrophic scars are indented or “sunken.” Acne scars are the classic example, including ice pick, boxcar, and rolling scars. These scars often respond best to procedures that stimulate collagen remodeling (like microneedling, lasers, or subcision) rather than topical gels alone.

Contracture scars can occur after burns and may tighten skin, limiting motion. They typically require specialist care and sometimes surgery or physical therapy.

Key Factors That Affect Scar Healing and Appearance

Two people can have the same surgery and end up with very different scars. That is normal, and it is not always a reflection of “doing something wrong.”

1) Genetics and skin type

Your tendency to form hypertrophic scars or keloids is strongly influenced by genetics. If you or close relatives have raised scars, your risk is higher. Melanin-rich skin also has a higher risk of post-inflammatory hyperpigmentation, meaning scars can look brown or gray for longer, especially if they are exposed to sun.

2) Wound tension and location

Scars that sit across high-movement areas (chest, shoulders, joints) or areas under tension tend to widen or thicken more easily. Surgeons often plan incisions along natural skin lines to reduce tension, but movement still matters during recovery.

3) Inflammation, infection, and delayed healing

When a wound takes longer to close, your body stays in an inflammatory state longer. More inflammation often leads to more redness, thicker collagen deposition, and a longer remodeling phase. Signs of possible infection like spreading redness, increasing pain, warmth, drainage, or fever should be evaluated promptly.

4) UV exposure and pigment changes

Sun exposure is one of the most preventable reasons scars stay darker. UV light can trigger excess pigment in healing skin and make redness linger. This matters even for “small” scars because pigment can be harder to fade than texture.

5) Consistency and contact time

Topical scar treatments work best when they are used correctly, on intact skin, and consistently over weeks to months. Skipping days, applying too thickly, or stopping too soon are common reasons patients feel a product “did nothing.” In many clinical settings, the routine that a patient can maintain wins over the routine that looks best on paper.

Treatment Overview: Allantoin vs Cepalin (Onion Extract) vs Silicone

If you are comparing allantoin vs silicone for scars, it helps to separate two goals: improving symptoms (itching, tightness, dryness) and improving long-term appearance (thickness, color, pliability). Different ingredients shine in different ways.

Silicone gel for scars: why it is first-line in many practices

Topical silicone is widely recommended for scar management, especially for new surgical scars and hypertrophic scars. Silicone does not “erase” a scar, but it can improve how raised, red, and firm it becomes during remodeling.

Silicone works mainly by forming a breathable barrier over the scar that helps regulate hydration and reduces excess signaling that can drive abnormal collagen. Many patients notice practical benefits too: less itching and a smoother feel once the gel dries.

This is why BIOCORNEUM developed patented SiliShield® technology. The crosslinked silicone creates a flexible, breathable barrier that hydrates scar tissue while protecting against UV damage that can darken healing scars. Because it includes broad-spectrum SPF 30, it also addresses one of the biggest day-to-day scar risks: sun exposure during the months your scar is actively remodeling.

If you want to see the product details, visit BIOCORNEUM silicone scar gel with SPF 30.

Allantoin scar gel: what it can do, and what it cannot

Allantoin is a common skincare ingredient used to soothe and soften skin. In scar products, it is often included to support comfort by reducing dryness and rough texture. If your scar feels tight, flaky, or irritated, an allantoin scar gel can feel calming.

Now, when it comes to changing scar thickness or preventing raised scars, allantoin alone has less robust evidence than silicone. Many formulas pair allantoin with other ingredients, so improvements can be hard to attribute to allantoin specifically. Consider this: scar remodeling is driven by collagen organization and inflammation signaling over time. Hydrating and soothing ingredients can help the surface feel better, but they may not provide the same barrier effect and collagen regulation support associated with silicone.

Onion extract (cepalin botanical extract): how it is used

Cepalin is a botanical extract derived from onion (Allium cepa). It appears in several over-the-counter scar gels and is often marketed for scar discoloration and texture. Onion extract contains compounds with anti-inflammatory and antioxidant properties in laboratory settings, which is part of the rationale for using it on scars.

The reality is that human studies on onion extract gels show mixed results. Some trials suggest modest improvements in scar softness or redness for certain scars, while others show little difference compared with basic moisturizers. Many onion-extract products also include other ingredients such as allantoin, which can improve feel and hydration but does not necessarily equal stronger scar remodeling results.

Mederma vs silicone gel: what “better” usually means clinically

Patients often ask about “silicone scar gel vs Mederma.” Mederma is commonly associated with onion extract based formulas and may include supporting ingredients like allantoin depending on the version. Silicone gels are typically evaluated as a category with stronger clinical consensus for preventing and treating hypertrophic scars.

From clinical experience, when the primary goal is to reduce the chance of a scar becoming thick and persistently red, silicone is usually the first choice. Onion extract or allantoin-based products may be reasonable when your main issue is dryness, mild irritation, or when you cannot tolerate a silicone product, but expectations should stay realistic.

Clinical evidence and what it realistically supports

Clinical studies demonstrate BIOCORNEUM's effectiveness in reducing scar redness, thickness, and discoloration. The dual-action formula addresses the two most critical factors in optimal scar healing: a consistent silicone barrier for scar remodeling support, and built-in sun protection to help reduce UV-related darkening during healing.

If you want a broader overview of what treatments exist and how they compare, see Introduction to Scars Treatments 2025.

When topical treatment is not enough

Topicals can help many scars, but some scar types respond best to in-office care. Raised scars and keloids may require steroid injections, pressure therapy, or lasers. Atrophic acne scars often improve more with microneedling, resurfacing lasers, chemical peels, or subcision. For context on what “scar removal” can truly mean, read Can Scars Be Permanently Removed? A Complete Guide to Scar Removal.

Prevention Strategies: Why Early Intervention Matters

Scar prevention is not about perfection. It is about stacking small advantages early, when the scar is biologically active and most responsive.

Start at the right time

Only start topical scar products once the skin surface is fully closed and your surgeon or dermatologist confirms it is safe. Using gels on open skin can irritate the area and increase infection risk. If you had stitches removed, a graft, or a complication, your “start date” may be later than someone else’s.

Protect your scar from sun, even when it looks “fine”

UV exposure can darken healing skin and prolong redness. This is especially important for scars on the chest, face, arms, and any area that sees regular daylight. Physical coverage like clothing helps, but many scars are still exposed in daily life.

If you use a silicone gel that includes sun protection, it simplifies your routine. You apply one layer and you know you are addressing both scar barrier support and daily UV risk.

Support the incision during early remodeling

Follow your surgeon’s instructions on activity restrictions, stretching, and massage. Excess pulling early on can widen scars. Once your provider clears massage, gentle scar massage can help soften tightness for some patients by improving pliability. It should never be painful or cause the scar to reopen.

Do the basics that keep inflammation down

• Keep the area clean and avoid picking at scabs or peeling skin.
• Avoid nicotine exposure, which can impair wound healing.
• Prioritize protein, hydration, and sleep, since repair is energy-intensive.
• Contact your clinician if you notice increasing pain, drainage, spreading redness, or a rapidly thickening scar.

If you want a step-by-step routine that covers timing and realistic expectations, see Guide to Scar Care 101.

Expert Tips: How Dermatology Teams Think About Scar Products

Standing in the aisle comparing tubes, it can feel like you are supposed to choose the “perfect” product. A better approach is to choose the product that best matches your scar type, your skin, and your ability to stay consistent.

Match the product to your scar goal

If your scar is new, pink, and starting to feel firm or raised, silicone is often the most evidence-aligned option. If your scar mainly feels dry or itchy but is flat and fading normally, soothing ingredients such as allantoin can be helpful for comfort.

Look for a wearable texture

Many people stop using scar gel because it feels sticky or pills under sunscreen or makeup. The best scar routine is the one you can keep up for 8 to 12 weeks for new scars, and longer for older scars. A fast-drying silicone gel can make daily use more realistic.

Be cautious with fragrance and irritants

Healing skin is reactive. Fragrance and harsh actives can trigger irritation that makes redness last longer. If you develop burning, rash, or significant itching after applying any scar product, stop and check in with your clinician.

Track progress like a clinician would

Take a photo every 2 to 4 weeks in the same lighting. Pay attention to thickness, redness, and how the scar feels, not just color alone. If you feel stuck, your dermatologist can tell whether you are seeing normal remodeling or early hypertrophic change that might benefit from procedures.

For patients who want a simplified routine, many surgeons recommend a silicone gel that also helps protect scars from sun. If that fits your situation, you can review BIOCORNEUM SPF 30 silicone scar gel as one example of a dual-purpose option used in post-procedure care.

How to Apply Scar Gel Correctly (Timing, Amount, Layering)

One of the biggest real-world gaps between “this ingredient works” and “this worked for me” is application technique. Topical scar products are designed for intact, healed skin. They need consistent contact time, and they need the right thickness to form a smooth film rather than a tacky layer.

Step 1: Confirm your scar is ready

Only begin once the incision is fully closed: no scabs, no drainage, no open areas, and no signs of infection. Many patients are cleared around 2 to 4 weeks after surgery, but the safest timing is the timing your surgeon confirms based on your closure method, location, and healing.

Step 2: Clean, then fully dry

Wash gently with mild soap and water if your clinician has cleared you to do so, then pat dry. Scar gels adhere and dry best when the skin is completely dry. Applying to damp skin can lead to pilling and uneven coverage.

Step 3: Apply a thin, even layer

With silicone gels, more is not better. A thin film is the goal. If you can see a thick, wet layer sitting on the scar several minutes later, you likely used too much. Over-application can feel sticky, transfer to clothing, and make some people give up on treatment early.

Step 4: Let it dry before layering anything on top

Let the product dry completely before dressing, putting on compression garments, or applying cosmetics. In general, if you are using a silicone gel with SPF, you also want to allow it to dry before sun exposure. If you are using other skincare or makeup, apply them only after the silicone film has set.

Step 5: Aim for consistent daily contact time

In scar care, consistency beats intensity. Many clinical protocols for silicone-based scar care use daily application for several months, because the remodeling phase is long. If you are only able to be consistent once per day, talk with your clinician about how to build the most realistic routine for your scar and lifestyle.

Step 6: Add massage only when your clinician clears it

Scar massage can help some people with pliability and tightness, especially when the scar feels firm. However, massage should never be started on an incision that is still fragile. Once cleared, use gentle pressure and stop if you notice pain, bleeding, skin breakdown, or increasing inflammation.

What “layering with sunscreen” really means

Many scars need sun protection for months, especially on the face, chest, shoulders, and arms. If your silicone gel already includes broad-spectrum SPF 30, that simplifies the routine and reduces missed days of protection. If you use a separate sunscreen, allow each layer to set to reduce pilling, and remember that sunscreen generally needs reapplication with prolonged outdoor exposure.

For general prevention guidance, the American Academy of Dermatology emphasizes sun protection after a wound has healed to help reduce red or brown discoloration and support better fading over time.

Silicone Gel vs Silicone Sheets: Which Is Better for Your Scar?

“Silicone” is the best-studied topical category for scar management, but patients still have to choose a format: gel or sheets. Clinically, both can be effective. The best choice is usually the one that you can wear consistently on your specific scar location.

When silicone gel can be the better fit

• High-movement or contoured areas: joints, the face, and areas where a sheet lifts or wrinkles.
• Scars you want to keep discreet: gel dries clear and can be easier to use under clothing or makeup.
• Multiple small scars: gel can be more practical than cutting multiple pieces of sheeting.

When silicone sheets can be the better fit

• Broad, flatter areas: areas where a sheet can sit smoothly for long wear time.
• Patients who prefer longer wear: some people find it easier to put on a sheet and leave it rather than remember applications.
• When your clinician recommends a combined approach: a common strategy is gel during the day (especially if you need a clear finish) and sheeting at night for extended contact time.

What studies suggest about silicone formats

Randomized and comparative studies in scars, including hypertrophic scars after burns, suggest silicone therapy improves scar quality over time. One randomized trial in the journal Burns (2009) compared silicone gel, silicone gel sheeting, and a topical onion extract formulation that included heparin and allantoin in post-burn hypertrophic scars. Improvements were seen across groups, but silicone treatments (gel or sheeting) performed better than the onion extract formulation on Vancouver Scar Scale outcomes. This is one reason many clinicians treat silicone as first-line for raised scars.

In practice, gel vs sheets is rarely about “which is stronger” and more about which format you can keep on the scar reliably.

Safety and Who Should Check With a Clinician First

Scar care is generally straightforward, but there are a few safety points that matter. The biggest risks are starting too early, trapping irritation under a barrier, or missing signs that a scar is not healing normally.

Do not apply scar products on open or infected skin

Any scar gel, whether it is silicone-based or contains soothing ingredients like allantoin, should be used only on intact skin. If you have drainage, open areas, increasing warmth, spreading redness, or fever, your clinician should evaluate the wound before you apply topical products.

Watch for irritation and allergic contact dermatitis

Even gentle products can trigger a reaction in healing skin. If you notice burning, a new rash, swelling, or worsening itch that is not typical healing itch, stop the product and contact your clinician. This can be especially important if a product includes fragrance or botanical extracts, which are more likely to irritate sensitive skin.

Extra caution for keloid-prone patients

If you have a personal or family history of keloids, do not wait months to ask for help if a scar becomes rapidly raised, itchy, or expands beyond the incision. Topical care can be supportive, but keloids often require in-office treatment plans (commonly injections and sometimes lasers) to control growth.

Pregnancy and breastfeeding

Many patients ask about scar care after pregnancy-related procedures such as C-section. In general, topical silicone is widely used on healed skin, but individual product ingredients can vary, especially when sun protection filters are included. If you are pregnant or breastfeeding, it is reasonable to review the ingredient list with your obstetric clinician or dermatologist, especially for scars on large surface areas or if you have a history of skin sensitivity.

Children and sensitive skin

Pediatric scars can behave differently, and some children are prone to irritation. If you are treating a child’s scar, discuss timing and product choice with the child’s clinician, and choose simple routines that prioritize tolerance and consistency.

When to seek evaluation for a scar

• The scar becomes raised and firm quickly, especially within the first 1 to 2 months.
• The scar grows beyond the wound border.
• You have significant pain, persistent burning, or worsening redness.
• The scar crosses a joint and starts limiting motion.
• You feel “stuck” with redness and thickness that is not improving over several months.

Early evaluation can open the door to options like laser therapy for redness, injections for raised scars, or structured silicone plus pressure strategies for high-risk scars. It also helps you avoid unnecessary product switching that delays consistent care.

Frequently Asked Questions

Which is better: allantoin vs silicone for scars?

It depends on your goal. Allantoin is mainly a soothing, skin-softening ingredient that can help with dryness and comfort. Silicone has stronger clinical support for improving scar thickness, redness, and overall appearance, especially for newer surgical scars and hypertrophic scars. If your scar is raised or staying very red, silicone is usually the more evidence-based first choice. If your scar is flat but irritated, an allantoin-containing product may help you tolerate a routine. Ask your surgeon or dermatologist which option matches your scar type.

What is cepalin, and is cepalin botanical extract proven for scars?

Cepalin botanical extract is derived from onion (Allium cepa) and is included in some over-the-counter scar gels. Research results are mixed. Some studies show modest improvements in scar texture or redness for select scars, while others show minimal difference compared with simple moisturizers. Cepalin may help some patients, but it is not considered as consistently supported as silicone for preventing and treating raised scars. If you choose a cepalin product, be prepared to use it consistently for several months and track changes objectively.

Is “silicone scar gel vs Mederma” an equal comparison?

Not exactly. Silicone scar gels are a category with broad clinical acceptance for scar management. Mederma is a brand often associated with onion extract based formulas, and some versions include other ingredients such as allantoin. Both can be used on closed, healed skin, but they do not work the same way. If your top priority is reducing the risk of a thick, raised scar, silicone is more commonly recommended. If comfort and surface softness are your main issues, onion extract or allantoin-based gels may feel beneficial.

When should I start using scar gel after surgery?

Start only after the skin is fully closed and your surgeon confirms it is safe. For many patients, that is after stitches are removed or once scabs are gone and there is no drainage. Starting too early can irritate healing tissue or increase infection risk. Once you start, consistency matters more than using a thick layer. Apply as directed and give it time. If your incision had complications, your start date may be later, so follow your post-op instructions closely.

How long does it take to see results from scar gel?

Most scars change slowly. Newer scars often show visible improvements in redness, comfort, and early thickness over about 8 to 12 weeks of consistent use, with continued remodeling for many months. Older scars can take longer and may improve more gradually. Your scar’s final appearance typically evolves over 6 to 24 months. For a timeline-focused guide, see How Long Do Scars Take to Fade?. If a scar is rapidly thickening or becoming very itchy, consider an early dermatology visit.

Will scar gel help with dark scars or hyperpigmentation?

Scar gels may help indirectly by supporting a healthy healing environment, but pigment changes have multiple causes. Sun exposure is a major driver of post-inflammatory hyperpigmentation in scars, especially in darker skin tones. Daily broad-spectrum sun protection is one of the most practical ways to reduce lingering discoloration. If pigment is your biggest concern, consider a routine that includes UV protection plus a scar-supporting barrier. Your dermatologist may also recommend targeted pigment treatments once the scar is stable.

Do silicone gels work on old scars?

Silicone gels can still help some older scars feel softer and look more even, but results are usually more modest than with newer scars. Older scars have completed more of their collagen remodeling, so they are less “active” biologically. Consistent use over several months can be worth trying, especially if the scar is still firm, itchy, or uneven. If an old scar is significantly raised or limiting motion, talk with your clinician about in-office options such as injections, lasers, or other procedural treatments.

What if my scar is raised and itchy? Is that a keloid?

Raised, itchy scars can be hypertrophic scars or keloids. A hypertrophic scar stays within the original incision or wound edges, while a keloid grows beyond them. Both can itch or feel tender. Early evaluation is helpful because treatments like silicone, pressure strategies, steroid injections, or lasers may work better when started sooner. If your scar is expanding beyond the original wound, or if you have a history of keloids, do not wait it out on your own. Your dermatologist can confirm the scar type and guide next steps.

Can topical products fix acne scars?

Topicals may help with color and overall skin comfort, but most indented acne scars (atrophic scars) usually need collagen-stimulating procedures for meaningful texture change. That can include microneedling, lasers, chemical peels, or subcision, depending on scar type and skin tone. If you are dealing with acne-related scarring, you may find it helpful to read Acne Scars: Understanding and Treatment Options and then talk with a dermatologist about a personalized plan.

How much scar gel should I apply?

Use the thinnest layer that fully covers the scar. The goal is a smooth film, not a thick coating. If the product stays wet, feels very sticky, or transfers easily to clothing long after application, that often means too much was applied.

Can I wear makeup over silicone scar gel?

Often, yes, once the silicone gel has fully dried. Let the film set completely first, then apply cosmetics gently to reduce pilling. If you are treating a facial scar and notice irritation from makeup or removal wipes, consider simplifying products while the scar is still pink and reactive.

Is silicone gel or silicone sheeting better for raised scars?

Both formats are used in clinical scar care. The “better” option is usually the one you can keep on consistently. Sheeting can provide prolonged contact time, while gel can be easier to use on contoured or high-movement areas. Some clinicians use a combination approach for extended daily coverage.

What if I get a rash from my scar product?

Stop the product and contact your clinician, especially if you have swelling, blistering, worsening redness, or burning. A rash can be a sign of contact dermatitis (skin inflammation triggered by irritation or allergy). Your clinician can help you identify whether it is the product, an adhesive, or another factor, and suggest a safer plan.