The Power of Vitamin C in Skincare: A 2025 Guide to Radiant Skin
Introduction
In 2025, the popularity of Vitamin C in skincare continues to soar. This powerhouse ingredient has become a staple in skincare routines worldwide, promising brighter, healthier skin. From serums to moisturizers, Vitamin C is now infused into countless products, thanks to its ability to fight dullness, hyperpigmentation, and fine lines.
With the rise of social media beauty trends and scientific advancements, more people are turning to evidence-based skincare. Dermatologists, estheticians, and beauty influencers consistently praise Vitamin C for its ability to enhance skin health, boost collagen production, and combat environmental damage. Whether you’re a skincare beginner or a seasoned beauty enthusiast, understanding the benefits and science behind Vitamin C can help you achieve radiant, youthful skin.
The Rise of Vitamin C as a Must-Have Skincare Ingredient in 2025
The demand for Vitamin C in skincare has skyrocketed, making it one of the most sought-after ingredients in the beauty industry. Several factors contribute to its growing popularity:
-
Social Media Influence—Platforms like TikTok, Instagram, and YouTube have amplified the conversation around Vitamin C. Skincare experts and influencers share before-and-after results, convincing more people to incorporate it into their routines.
-
Scientific Backing—Research on Vitamin C’s effectiveness continues to expand, reinforcing its reputation as a top-tier skincare ingredient. Dermatologists increasingly recommend it for improving skin texture, reducing dark spots, and protecting against premature aging.
-
Sustainable and Natural Beauty Trends – Consumers are shifting toward clean, plant-based skincare, and Vitamin C, often derived from natural sources like citrus fruits, fits the trend perfectly.
-
Advanced Formulations—Skincare brands have improved Vitamin C formulas, making them more stable and effective. Newer innovations prevent oxidation, ensuring maximum potency for better results.
From high-end luxury brands to affordable drugstore options, nearly every skincare line now features a Vitamin C product, proving its dominance in the industry.Why Dermatologists and Beauty Experts Recommend Vitamin C for All Skin Types
Vitamin C is universally beneficial, making it suitable for all skin types, from oily and acne-prone to dry and sensitive. Here’s why skincare professionals swear by it:
1. Brightens and Evens Out Skin Tone
Hyperpigmentation, dark spots, and dull skin are common concerns that Vitamin C effectively addresses. It inhibits melanin production, helping to fade discoloration and create a radiant complexion.
2. Boosts Collagen Production
Collagen is essential for firm, youthful skin, but its production declines with age. Vitamin C stimulates collagen synthesis, reducing the appearance of fine lines and wrinkles.
3. Provides Antioxidant Protection
Exposure to UV rays, pollution, and free radicals can damage skin cells, leading to premature aging. Vitamin C acts as a powerful antioxidant, neutralizing these harmful effects and preventing oxidative stress.
4. Hydrates and Strengthens the Skin Barrier
While primarily known for brightening, vitamin C also supports skin hydration. Some formulations include additional humectants like hyaluronic acid to enhance moisture retention.
5. Reduces Inflammation and Redness
For those with sensitive or acne-prone skin, Vitamin C helps calm irritation and reduce redness. It supports skin healing and minimizes post-acne marks.
With benefits that cater to various skin concerns, it’s no wonder dermatologists recommend Vitamin C as a key ingredient in any skincare regimen.
The Science Behind Vitamin C’s Brightening and Anti-Aging Effects
Understanding the science behind vitamin C reveals why it is so effective in skincare.
How Vitamin C Brightens the Skin
Tyrosinase is an enzyme responsible for melanin production. Vitamin C, especially in its purest form (L-ascorbic acid), inhibits its activity. By blocking excess melanin formation, vitamin C helps fade dark spots and promotes an even skin tone.
Additionally, Vitamin C enhances skin cell turnover, allowing fresher, brighter skin to emerge. This process helps combat dullness and gives the skin a natural glow.
How Vitamin C Fights Aging
Aging skin loses elasticity due to decreased collagen levels. Vitamin C stimulates fibroblasts, the cells responsible for collagen production, ensuring firmer, plumper skin. Regular use can improve skin texture and minimize fine lines.
Furthermore, vitamin C neutralizes free radicals, which accelerate aging by breaking down collagen and elastin. By preventing oxidative stress, vitamin C keeps the skin looking youthful and resilient.
Optimal Forms of Vitamin C for Skincare
There are several forms of vitamin C used in skincare, each with varying levels of stability and effectiveness:
-
L-Ascorbic Acid—The purest and most potent form, but it can be unstable and prone to oxidation.
-
Sodium Ascorbyl Phosphate—A stable, water-soluble derivative that is gentle on sensitive skin.
-
Magnesium Ascorbyl Phosphate—A milder form with excellent hydrating properties.
-
Tetrahexyldecyl Ascorbate—An oil-soluble form that penetrates deeply into the skin for long-lasting benefits.
Choosing the right formulation depends on skin type and concerns, but all forms contribute to Vitamin C’s brightening and anti-aging effects.
What is Vitamin C, and How Does It Benefit Your Skin?
An Overview of Vitamin C as an Antioxidant
Vitamin C, also known as ascorbic acid, is a powerful antioxidant that plays a crucial role in skin health. Found naturally in citrus fruits, berries, and leafy greens, this essential vitamin is widely used in skincare for its ability to protect, repair, and rejuvenate the skin.
As an antioxidant, Vitamin C neutralizes free radicals—unstable molecules that damage skin cells due to environmental factors like UV radiation, pollution, and stress. These free radicals accelerate aging, leading to fine lines, wrinkles, and dullness. By reducing oxidative stress, Vitamin C helps maintain a youthful and radiant complexion.
Moreover, Vitamin C enhances the skin’s natural defense mechanisms. It strengthens the skin barrier, reducing moisture loss and improving overall hydration. This benefit makes it an essential ingredient for all skin types, including dry, sensitive, and acne-prone skin.
How Vitamin C Boosts Collagen Production and Reduces Wrinkles
Collagen: The Foundation of Youthful Skin
Collagen is the most abundant protein in our skin, responsible for its structure, firmness, and elasticity. However, as we age, collagen production declines, leading to sagging skin and the formation of wrinkles. This is where vitamin C plays a crucial role.
1. Stimulating Collagen Synthesis
Vitamin C is essential for collagen synthesis. It activates fibroblasts, the cells responsible for producing collagen and elastin. By stimulating these cells, vitamin C helps maintain skin firmness and prevent the formation of fine lines.
2. Preventing Collagen Breakdown
Apart from boosting collagen production, Vitamin C also prevents its degradation. Free radicals and environmental aggressors break down collagen fibers, leading to premature aging. Vitamin C neutralizes these harmful molecules, preserving the skin’s elasticity.
3. Improving Skin Texture and Firmness
Regular use of Vitamin C in skincare enhances skin texture, making it smoother and more resilient. It plumps up the skin, reducing the depth of wrinkles and giving the face a youthful appearance.
To maximize these anti-aging benefits, dermatologists recommend using a vitamin C serum daily, preferably in the morning, followed by sunscreen to protect against UV-induced collagen damage.
Vitamin C’s Role in Fading Dark Spots and Evening Out Skin Tone
Hyperpigmentation, dark spots, and an uneven skin tone are common concerns for many people. Vitamin C is widely recognized for its ability to brighten the skin and reduce discoloration.
1. Inhibiting Melanin Production
Melanin is the pigment responsible for skin color. Overproduction of melanin, triggered by sun exposure, inflammation, or hormonal changes, leads to dark spots and uneven skin tone. Vitamin C inhibits tyrosinase, the enzyme responsible for melanin production, preventing excessive pigmentation.
2. Fading Existing Dark Spots
Vitamin C accelerates skin cell turnover, allowing new, healthier skin cells to replace pigmented ones. Over time, this process results in a more even complexion and a natural glow.
3. Reducing Post-Inflammatory Hyperpigmentation
For those with acne-prone skin, Vitamin C helps fade post-inflammatory marks left behind by breakouts. Its anti-inflammatory properties calm redness and irritation while promoting healing.
4. Enhancing the Effects of Sunscreen
While Vitamin C does not replace sunscreen, it works synergistically with SPF to prevent UV-induced pigmentation. Applying a vitamin C serum in the morning enhances the skin’s ability to fight sun damage, reducing the risk of dark spots.
For best results, look for stabilized Vitamin C formulations combined with other skin-brightening ingredients like niacinamide or ferulic acid. The combination ensures maximum efficacy in achieving a clear, radiant complexion.
Vitamin C revolutionizes skincare by providing numerous benefits that address aging, pigmentation, and overall skin health. Incorporating this antioxidant into your daily routine can lead to visibly brighter, firmer, and more youthful-looking skin.
Types of Vitamin C Used in Skincare
L-Ascorbic Acid—The Most Potent Form of Vitamin C
L-Ascorbic Acid (LAA) is the purest and most powerful form of Vitamin C used in skincare. It is highly effective at brightening the skin, reducing dark spots, and stimulating collagen production. However, its potency comes with a drawback—it is unstable and can easily degrade when exposed to air, light, or heat.
Benefits of L-Ascorbic Acid in Skincare
- Powerful Antioxidant Protection – Neutralizes free radicals, preventing premature aging and sun damage.
- Brightening and Even Skin Tone—Fades hyperpigmentation, dark spots, and post-inflammatory acne marks.
- Collagen Boosting—Stimulates collagen synthesis, making skin firmer and reducing fine lines.
Challenges of Using L-Ascorbic Acid
- Highly Unstable—Oxidizes quickly and loses effectiveness over time.
- Can Be Irritating—Higher concentrations (15–20%) may cause redness or sensitivity, especially for dry or sensitive skin.
- Requires Proper Storage—Must be stored in airtight, dark bottles to prevent oxidation.
Best Practices for Using L-Ascorbic Acid
- Look for serums with ferulic acid and vitamin E, as these ingredients stabilize LAA and enhance its potency.
- Use in the morning routine, followed by sunscreen to maximize UV protection.
- Start with a lower concentration (10%) if you have sensitive skin, then gradually increase.
Sodium Ascorbyl Phosphate—Stable and Gentle for Sensitive Skin
Sodium Ascorbyl Phosphate (SAP) is a water-soluble derivative of Vitamin C that is much more stable than L-Ascorbic Acid. It is an excellent option for those with sensitive or acne-prone skin, as it provides Vitamin C benefits without irritation.
Benefits of Sodium Ascorbyl Phosphate
- Stable and Long-Lasting—Unlike LAA, it does not oxidize quickly, making it more shelf-stable.
- Gentle and Non-Irritating—Ideal for those with sensitive skin, as it is less likely to cause redness or burning.
- Antibacterial Properties – Reduces acne breakouts by inhibiting acne-causing bacteria.
- Brightening Effects—Gradually improves skin tone and reduces pigmentation.
Best Practices for Using Sodium Ascorbyl Phosphate
- Works well in lightweight serums or moisturizers that can be used daily.
- Can be combined with niacinamide for enhanced skin-brightening effects.
- Suitable for both morning and evening use without causing any irritation.
Magnesium Ascorbyl Phosphate—Best for Hydration & Skin Barrier Support
Magnesium Ascorbyl Phosphate (MAP) is another water-soluble Vitamin C derivative that stands out for its hydrating and skin-soothing properties. Unlike LAA, it does not require a low pH to be effective, making it a great option for dry or dehydrated skin.
Benefits of Magnesium Ascorbyl Phosphate
- Hydrating and Moisturizing—Helps the skin retain moisture, making it an excellent choice for dry skin.
- Supports the Skin Barrier—Strengthens the skin’s natural defense, reducing water loss and irritation.
- Mild Yet Effective—Provides antioxidant protection and brightening effects without the harshness of LAA.
- Collagen Production—Plays a crucial role in maintaining skin elasticity and firmness.
Best Practices for Using Magnesium Ascorbyl Phosphate
- Look for creams and lotions with MAP for added hydration.
- Ideal for sensitive skin types who cannot tolerate LAA.
- Can be used alongside retinol or exfoliating acids without causing irritation.
Tetrahexyldecyl Ascorbate (THD Ascorbate)—Oil-Soluble for Deep Penetration
Tetrahexyldecyl Ascorbate (THD Ascorbate) is a highly stable, oil-soluble vitamin C derivative that penetrates deep into the skin. It is one of the most effective forms for reducing hyperpigmentation and promoting long-term anti-aging benefits.
Benefits of Tetrahexyldecyl Ascorbate
- Deep Skin Penetration—Due to its oil-soluble nature, it penetrates deeper layers of the skin than its water-based counterparts.
- Highly Stable—Unlike LAA, it does not oxidize quickly, ensuring long-lasting effectiveness.
- Strong Anti-Aging Effects—Stimulates collagen and elastin production for firmer, smoother skin.
- Works Well with Other Skincare Ingredients—Can be combined with retinoids, peptides, and other antioxidants.
How to Choose the Right Vitamin C Product
Which One Works Best: Serums, Creams, or Powders?
Vitamin C comes in various formulations, each offering unique benefits. Choosing between serums, creams, and powders depends on your skin type, concerns, and how you prefer to apply skincare products.
1. Vitamin C Serums—The Most Effective Choice
Serums are the most popular and potent form of vitamin C in skincare. They are lightweight, fast-absorbing, and formulated with high concentrations of active ingredients.
Best For:
✔ All skin types, especially normal, combination, and oily skin.
✔ Targeting hyperpigmentation, fine lines, and dullness.
Pros:
✔ Penetrates deeply into the skin for maximum efficacy.
✔ Delivers a high concentration of Vitamin C (typically 10% to 20%).
✔ Easily layered with other skincare products.
Cons:
✖ Can be unstable and oxidize quickly if not stored properly.
✖ Some formulas may irritate sensitive skin, especially at higher concentrations.
How to Use:
✔ Apply in the morning after cleansing but before moisturizer and sunscreen.
✔ Look for serums with ferulic acid and vitamin E, as these ingredients stabilize vitamin C and enhance absorption.
2. Vitamin C Creams—Best for Hydration and Gentle Effects
Cream-based vitamin C products are ideal for those who need hydration along with antioxidant benefits. Typically, they combine moisturizing ingredients with a lower concentration of Vitamin C.
Best For:
✔ Dry, sensitive, or mature skin types.
✔ Those who prefer a simpler skincare routine without layering multiple products.
Pros:
✔ Provides hydration while delivering Vitamin C benefits.
✔ Less likely to cause irritation than high-concentration serums.
✔ More stable than serums, reducing the risk of oxidation.
Cons:
✖ Lower potency compared to serums, meaning slower results.
✖ May not penetrate as deeply into the skin.
How to Use:
✔ Apply as the final step in your skincare routine (before sunscreen in the morning).
✔ Works well when paired with hyaluronic acid or peptides for added anti-aging benefits.
3. Vitamin C Powders—Highly Stable & Customizable
Vitamin C powders are a relatively new innovation in skincare. These powders must be mixed with a liquid (like a serum or moisturizer) before application.
Best For:
✔ Skincare enthusiasts who want to customize their Vitamin C concentration.
✔ Those who need a stable option that won’t degrade quickly.
Pros:
✔ Highly stable, meaning it won’t oxidize easily.
✔ Allows you to control the concentration of Vitamin C.
✔ More affordable because a small amount lasts a long time.
Cons:
✖ Requires mixing before each use, which may be inconvenient.
✖ Improper dilution can make it too potent and cause irritation.
How to Use:
✔ Mix a small amount (a pinch or ¼ teaspoon) into your favorite serum or moisturizer before applying.
✔ Use at night if you experience irritation with daytime use.
The Importance of Vitamin C Concentration Levels (10% to 20%)
The effectiveness of vitamin C largely depends on its concentration. Using the right percentage ensures you get the maximum benefits without causing irritation.
1. Low Concentrations (5% to 10%)—Best for Beginners & Sensitive Skin
✔ Provides antioxidant protection without irritation.
✔ Helps with mild hyperpigmentation and early signs of aging.
✔ Ideal for people with rosacea or easily reactive skin.
2. Medium Concentrations (10% to 15%)—Balanced for Most Skin Types
✔ Effectively brightens skin and reduces dark spots.
✔ Boosts collagen production while being gentle enough for daily use.
✔ Works well when combined with niacinamide or hyaluronic acid.
3. High Concentrations (15%–20%)—Most Effective for Hyperpigmentation and Wrinkles
✔ Fades stubborn hyperpigmentation and acne scars.
✔ Provides strong antioxidant protection against environmental damage.
✔ Stimulates collagen production for firmer, more youthful skin.
Caution:
✖ Higher concentrations can be irritating, especially for sensitive skin.
✖ If you experience stinging or redness, reduce usage to every other day or switch to a lower percentage.
How to Check for Stabilized Formulas to Prevent Oxidation
Vitamin C is notoriously unstable, meaning it can degrade when exposed to air, light, and heat. Using a stabilized formula ensures you get the maximum benefits without losing potency.
1. Look for Dark or Airtight Packaging
✔ Amber or opaque glass bottles protect Vitamin C from light exposure.
✔ Airless pumps help prevent oxidation by limiting air exposure.
✖ Avoid products in clear bottles or jars, as they allow light and air to degrade vitamin C faster.
2. Check for Added Stabilizer Ingredients
Certain compounds help prevent oxidation and extend the shelf life of Vitamin C:
✔ Ferulic Acid—Enhances stability and doubles antioxidant power.
✔ Vitamin E (tocopherol)—Works with Vitamin C to boost effectiveness and longevity.
✔ Hyaluronic Acid—Maintains moisture and prevents breakdown.
A well-formulated product with these stabilizers will last longer and perform better.
3. Choose Vitamin C Derivatives if You Have Sensitive Skin
Pure L-ascorbic acid is the most effective form, but it is also the least stable. If you have sensitive skin or want a more long-lasting option, consider derivatives like:
✔ Sodium Ascorbyl Phosphate—Gentle, stable, and effective against acne.
✔ Tetrahexyldecyl Ascorbate (THD Ascorbate) – Oil-soluble and penetrates deeply.
✔ Magnesium Ascorbyl Phosphate—Hydrating and supports the skin barrier.
4. Check for Expiration Dates and Signs of Oxidation
✔ Fresh vitamin C products should be clear or pale yellow in color.
✔ If your vitamin C turns orange or brown, it has oxidized and is no longer effective.
✔ Always store your vitamin C in a cool, dark place to extend its shelf life.
How to Maintain Results and Prevent Skin Irritation
Using Vitamin C in your skincare routine delivers brightening, anti-aging, and protective benefits, but maintaining these results requires proper application and care. Follow these essential tips to ensure long-term improvements in skin tone, texture, and overall radiance.
1. Keep Using Vitamin C Regularly
To maintain your skin’s glow and anti-aging benefits, daily application is crucial. Stopping use can slow down collagen production and allow pigmentation to return.
2. Choose the Right Concentration
Vitamin C comes in different strengths, and selecting the right concentration ensures maximum benefits without irritation:
✔ 10–15% Vitamin C—Ideal for beginners and sensitive skin.
✔ 15–20% Vitamin C—More potent for stubborn dark spots and deep wrinkles.
✔ Above 20%—May cause irritation without providing extra benefits.
3. Store Your Vitamin C Properly
Vitamin C is sensitive to light, heat, and air, making proper storage essential to prevent oxidation.
✔ Store it in a dark, airtight bottle.
✔ Keep it in a cool, dry place (not in direct sunlight).
✔ Look for stabilized formulas containing ferulic acid or vitamin E to enhance longevity.
4. Avoid Mixing with Harsh Ingredients
To prevent irritation, do not combine Vitamin C with:
✖ Retinol—Can increase sensitivity when layered together.
✖ Benzoyl Peroxide—Oxidizes Vitamin C, making it ineffective.
✖ AHAs/BHAs—Increase the risk of over-exfoliation and irritation.
5. Always Wear Sunscreen
Vitamin C enhances sun protection, but it does not replace SPF. Always apply a broad-spectrum sunscreen (SPF 30+) every morning to prevent UV damage and maintain bright, healthy skin.
By following these steps, you can maximize the benefits of Vitamin C and keep your skin looking radiant and youthful for years to come.
Common Mistakes to Avoid When Using Vitamin C
Even though Vitamin C is a powerful ingredient, many people make mistakes that reduce its effectiveness or cause irritation. Avoid these common pitfalls to get the best results.
Using Expired or Oxidized Vitamin C (Turns Yellow or Brown)
One of the most common mistakes people make is using an expired or oxidized product. Vitamin C, especially in its purest form (L-ascorbic acid), is highly unstable and degrades quickly when exposed to air, light, or heat. When this happens, vitamin C loses its effectiveness and may even cause skin irritation.
How to Identify Oxidized Vitamin C
✔ Fresh Vitamin C serum is usually clear or light-milky in color.
✔ Oxidized vitamin C turns yellow, orange, or brown—a sign that it has broken down.
✔ If you notice any change in color or an unusual odor, stop using the product immediately.
Why Using Oxidized Vitamin C is Bad for Your Skin
✖ Reduced Effectiveness—An oxidized formula no longer brightens skin or reduces wrinkles.
✖ Potential Skin Damage—Instead of neutralizing free radicals, oxidized Vitamin C may generate free radicals, leading to irritation, redness, and breakouts.
How to Avoid This Mistake
✅ Buy small bottles that you can finish within 3 months.
✅ Choose stabilized Vitamin C formulas (e.g., those containing ferulic acid or Vitamin E).
✅ Always close the bottle tightly after each use to prevent oxidation.
Not Applying Sunscreen After Vitamin C (It Enhances Sun Protection!)
Many people assume vitamin C replaces sunscreen—but that’s a big mistake. While vitamin C offers antioxidant protection, it does not block UV rays like sunscreen does.
Why Sunscreen is Essential After Vitamin C
✔ UV Exposure Breaks Down Vitamin C—Without sunscreen, your Vitamin C serum loses its effectiveness faster.
✔ Vitamin C Enhances SPF Protection—When paired with sunscreen, Vitamin C boosts your skin’s defense against UV rays, reducing sun damage and hyperpigmentation.
✔ Skipping Sunscreen Increases Skin Damage—Unprotected sun exposure can reverse the brightening effects of Vitamin C, leading to more dark spots and premature aging.
How to Apply Sunscreen with Vitamin C
✔ Apply Vitamin C serum in the morning on clean skin.
✔ Follow with a moisturizer to lock in hydration.
✔ Finish with a broad-spectrum SPF 30+ sunscreen to shield your skin from UV damage.
Skipping sunscreen undoes the benefits of Vitamin C, so always use SPF to maximize its effects!
Storing Vitamin C Incorrectly—Best in Dark, Airtight Containers
Improper storage is another common mistake that leads to vitamin C degradation. Since vitamin C is sensitive to light, air, and heat, storing it incorrectly can cause it to oxidize faster.
Best Practices for Storing Vitamin C
✅ Keep it in a dark, airtight bottle—look for amber or opaque packaging to prevent light exposure.
✅ Store it in a cool, dry place—avoid keeping it in direct sunlight or humid environments like the bathroom.
✅ Refrigeration Can Help—Some vitamin C serums last longer when stored in the fridge, especially L-ascorbic acid formulas.
By avoiding these mistakes and handling vitamin C correctly, you can maximize its potency and achieve brighter, healthier skin!
Conclusion
Vitamin C is undeniably a powerhouse ingredient in skincare, offering a wide range of benefits for all skin types. From brightening dull skin and fading dark spots to boosting collagen production and protecting against environmental damage, this potent antioxidant is a must-have in any skincare routine. Its ability to fight free radicals, reduce fine lines, and even out skin tone makes it one of the most sought-after ingredients in the beauty industry.
However, to get the most out of Vitamin C, it’s essential to choose the right formulation based on your skin type and concerns. Whether it’s:
✔ L-Ascorbic Acid for maximum potency,
✔ Sodium Ascorbyl Phosphate for sensitive skin, or
✔ Tetrahexyldecyl Ascorbate for deep penetration,
Selecting the right version ensures optimal results.
By incorporating Vitamin C correctly—using it in the morning, storing it properly, pairing it with sunscreen, and avoiding oxidation—you can enjoy brighter, healthier, and more youthful skin.
FAQ
1. Can I use Vitamin C every day?
Yes! Vitamin C should be used daily, preferably in the morning, to protect against environmental stressors and enhance skin radiance.
2. What percentage of Vitamin C is best for beginners?
For beginners, start with a 10–15% concentration to allow your skin to adjust. Higher concentrations (15–20%) are more potent but can be irritating for sensitive skin.
3. Can I use vitamin C with retinol?
It’s best not to use Vitamin C and retinol together in the same routine, as both are potent actives. Use vitamin C in the morning and retinol at night to avoid irritation.
4. Why is my vitamin C serum turning yellow or brown?
This means the vitamin C has oxidized and lost its effectiveness. To prevent this:
✔ Store it in a dark, airtight bottle.
✔ Keep it in a cool, dry place.
✔ Replace it if it changes color.
5. How long does it take to see results from Vitamin C?
With consistent use, you should start seeing brighter skin within 4 weeks and noticeable improvements in dark spots and wrinkles within 8–12 weeks.