Same range. Different strengths and formulas. Compare the two 1 oz serums before choosing.
1.0 oz / 30 ml
A daily facial serum with 15% pure vitamin C, designed to brighten dull skin and help even skin tone. This is the lower-strength option of the two, recommended by Obagi for normal to combination skin.
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1.0 oz / 30 ml
A daily facial serum with 20% pure vitamin C, designed to brighten dull skin and help even skin tone. Obagi recommends it for normal to oily skin; it also contains sodium hyaluronate, a form of hyaluronic acid.
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Both contain vitamin C, fragrance and alcohol. The 20% formula also contains sodium hyaluronate and sorbitol.
14 of 14 ingredients shown
Vitamin C antioxidant
The main vitamin C active: an antioxidant that helps defend skin against oxidative stress.
L-ascorbic acid is pure vitamin C. You get a higher concentration in the 20% serum, but more does not automatically mean better results. How the serum is formulated also affects how much vitamin C reaches your skin. The study below looked at absorption, not which of these two Obagi serums works better.
Vitamin C derivative
A second form of vitamin C, which skin can convert into ascorbic acid.
Both serums contain this vitamin C derivative as well as pure vitamin C. Research in human skin models shows it can be converted into ascorbic acid. Obagi does not say how much is in either serum; the 15% and 20% on the bottles refer to L-ascorbic acid.
Source: Ascorbyl glucoside skin-delivery study (Jacques et al.)
Solvent and humectant
Helps dissolve other ingredients and retain moisture in a formula.
This ingredient does two jobs: it helps other ingredients dissolve and helps retain moisture. Both serums contain it, so moisture-supporting ingredients are not exclusive to the 20% version.
Source: COSMILE Europe: Propylene Glycol
Solvent
Provides a liquid base and dissolves ingredients that mix with water.
Water carries ingredients that dissolve in it. Both serums use it as part of their base. A water-based formula is not necessarily more hydrating; that depends on the other ingredients too.
Source: COSMILE Europe: Aqua
Solvent
Denatured ethanol helps dissolve ingredients and evaporates readily.
If you avoid denatured alcohol, neither serum is alcohol-free. Obagi does not give its concentration, so the ingredients alone cannot tell us which serum will feel more drying or comfortable.
Source: COSMILE Europe: Alcohol Denat.
Botanical extract; fragrance and skin conditioning
An orange-peel extract with cosmetic uses that include scent and skin conditioning.
You will find it under the name Citrus aurantium dulcis peel extract. Both serums contain it. An orange extract is not the same thing as a measured dose of vitamin C; compare the L-ascorbic acid percentages for that.
Source: COSMILE Europe: Citrus Aurantium Dulcis Peel Extract
Botanical skin-conditioning ingredient
An extract of grapefruit fruit pulp used for skin conditioning in cosmetics.
You will find it under the name Citrus paradisi fruit extract. Both serums contain it, so it is not an extra you get by choosing 20%. Obagi does not say how much either formula contains.
Fragrance
Adds scent. Neither serum is fragrance-free.
If you prefer fragrance-free skincare, neither is the right match. Parfum is the label name for fragrance and can cover a mixture of scent ingredients, rather than just one substance.
Source: COSMILE Europe: Parfum
Skin-conditioning ingredient
A salt form of hyaluronic acid, the water-retaining ingredient used in skincare.
Found in 20%, not 15%. If you look for hyaluronic acid in your skincare, this is the ingredient to notice. Its amount is not disclosed, so its presence alone does not show that the 20% serum is more hydrating.
Humectant
A water-attracting ingredient that helps a formula retain moisture.
A humectant is an ingredient that attracts and holds water. Only the 20% serum contains sorbitol. Alongside sodium hyaluronate, it is a useful reminder that 20% is a different formula, not simply the same serum with more vitamin C.
Source: Cosmetic Ingredient Review: Mannitol, Sorbitol and Xylitol
Solvent
Helps dissolve or carry other ingredients in a usable formula.
Only the 20% serum contains it. Think of it as part of the carrier for other ingredients, rather than an extra skincare benefit. Its presence does not tell us that the 20% serum delivers vitamin C better.
Source: Cosmetic Ingredient Review: Glycols, including Ethoxydiglycol
Preservative
Helps stop bacteria and other microbes growing in the product.
Only the 20% serum contains this preservative. That does not mean the 15% serum is unprotected: products can use different combinations of ingredients to stay preserved. One preservative is not enough to judge a whole formula's safety.
Source: Cosmetics Info: Phenoxyethanol
pH-control ingredient
Can help control how acidic or alkaline a cosmetic formula is.
Only the 20% serum contains it. It can help adjust pH during formulation, but it does not tell you the finished serum's pH. We cannot use it to say which serum is more acidic.
Astringent or antimicrobial ingredient
Has several cosmetic uses, including astringent and antimicrobial functions.
Only the 20% serum contains it. Obagi does not say why it is included or in what amount. Do not read it as an acne-treatment or oil-control claim for the serum.
Source: COSMILE Europe: Zinc Chloride
No ingredients match.
These 14 key ingredients are compared using Obagi's US ingredient lists. Formulas can change. Check the bottle before buying if you need to avoid a particular ingredient.
Obagi recommends 15% for normal to combination skin and 20% for normal to oily skin, including combination skin. That is a starting point, not a promise that either will suit you. Both contain fragrance and denatured alcohol.
If you are happy with 15%, the bigger number alone is not a reason to switch. The 20% serum has more vitamin C and a different formula, but we found no direct test showing it works better than 15%. Compare current prices for the same 1 oz size before deciding.
We found no direct test comparing these two serums. Obagi's research on 20% does not show that it beats 15%. We have not tested either product ourselves, and neither replaces sunscreen.
Obagi directs 5-7 drops in the morning after cleansing and toning, followed by moisturizer and SPF. Avoid eyes, nose, mouth and lips. Stop and consult a doctor if tingling becomes severe. Cap tightly, keep cool and dark at or below 77 F / 25 C, and use within 3-6 months after opening.
Based on Obagi's US product information, checked 20 October 2026. This is not a hands-on product test. Photos are from Obagi; ingredient explanations link to their sources.