Skin Candid Ingredient Library
Understand the ingredientbefore you buy the product.
Evidence-aware skincare ingredient guides covering useful concentrations, formulation limits, safety and realistic routine decisions.
Popular starting points
Featured ingredient guides.
Begin with the ingredients people most often compare, misunderstand or add too quickly.
Azelaic Acid
Azelaic acid has useful evidence for acne, post-acne marks and inflammatory rosacea, but the strongest studies use 15–20% rather than typical 10% cosmetic products.
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Hyaluronic Acid
Topical hyaluronic acid can improve hydration, but it is not filler in a bottle. Formula, moisturizer and realistic expectations matter more than a huge percentage.
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Niacinamide
Niacinamide can support the skin barrier and gradually improve uneven-looking tone. Learn what the evidence supports, why 2–5% is often enough, and how to use it without overcomplicating your routine.
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Retinol
Retinol can gradually improve fine lines and texture, but stability, irritation and pregnancy limits matter more than chasing the highest percentage.
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Salicylic Acid
Salicylic acid is best for clogged pores and mild comedonal acne. Choose one 0.5–2% format, start slowly and stop escalating when irritation appears.
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Vitamin C
Topical vitamin C can support uneven tone and antioxidant care, but chemical form, stability, packaging and sunscreen matter more than percentage alone.
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Start with the ingredient you are considering.
Each guide explains where the evidence is useful, where it becomes uncertain and how the ingredient fits into a realistic routine.
Azelaic Acid
Azelaic acid has useful evidence for acne, post-acne marks and inflammatory rosacea, but the strongest studies use 15–20% rather than typical 10% cosmetic products.
Read the guide
Centella Asiatica
Centella asiatica, often called cica, is a plant extract used in soothing and barrier-support products. Its triterpenes have biologic activity, but most everyday cosmetic claims are supported by less direct evidence than wound-care research.
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Ceramides
Ceramides are lipids naturally found in the outer skin barrier. In moisturizers, they can support hydration and barrier function—but the complete lipid blend and product texture matter more than the word ‘ceramide’ alone.
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Glycolic Acid
Glycolic acid is an alpha hydroxy acid used to exfoliate the skin surface and improve dullness, uneven texture and some types of visible pigmentation. Concentration and pH both matter.
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Hyaluronic Acid
Topical hyaluronic acid can improve hydration, but it is not filler in a bottle. Formula, moisturizer and realistic expectations matter more than a huge percentage.
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Lactic Acid
Lactic acid is an alpha hydroxy acid used for rough texture, dry body skin and keratosis pilaris. It is often marketed as a hydrating acid, but it can still sting, irritate and increase sun sensitivity.
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Mandelic Acid
Mandelic acid is an alpha hydroxy acid often promoted as a gentler option for acne and dark marks. Most useful clinical evidence, however, comes from professional peels or small formula-specific studies—not ordinary home serums.
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Niacinamide
Niacinamide can support the skin barrier and gradually improve uneven-looking tone. Learn what the evidence supports, why 2–5% is often enough, and how to use it without overcomplicating your routine.
Read the guide
Panthenol
Panthenol is a provitamin B5 ingredient used to support hydration, barrier comfort and recovery from irritation. It is useful, but it is a supportive moisturizer ingredient rather than a cure for eczema or damaged skin.
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Peptides
Peptides are short chains of amino acids used in skincare for hydration, barrier support and visible ageing claims. ‘Peptides’ is a broad category, so evidence for one peptide cannot be transferred to another.
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Retinal
Retinal is a topical vitamin A derivative positioned between retinol and prescription retinoic acid. It may improve visible photoageing and acne-related concerns, but it can still irritate and should be introduced gradually.
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Retinol
Retinol can gradually improve fine lines and texture, but stability, irritation and pregnancy limits matter more than chasing the highest percentage.
Read the guide
Salicylic Acid
Salicylic acid is best for clogged pores and mild comedonal acne. Choose one 0.5–2% format, start slowly and stop escalating when irritation appears.
Read the guide
Tranexamic Acid
Topical tranexamic acid is used for uneven pigmentation and melasma-focused skincare. Evidence is promising but heterogeneous, and it should not be confused with oral tranexamic acid.
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Vitamin C
Topical vitamin C can support uneven tone and antioxidant care, but chemical form, stability, packaging and sunscreen matter more than percentage alone.
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How to use this library
Do not choose an ingredient from reputation alone.
The useful question is whether the studied benefit matches your concern, the formula is tolerable and the routine remains simple enough to follow.
Match the concern
Look for evidence tied to the actual goal: acne, pigmentation, hydration, fine lines or another defined concern.
Read the limitation
Check whether research used a prescription strength, specific vehicle, different population or multi-ingredient formula.
Introduce one change
One new active at a time makes irritation easier to identify and keeps the routine manageable.
Independent editorial standards
Evidence before trends.
Claim-specific evidence
Hydration, acne, pigmentation and visible-ageing claims are assessed separately. One strong claim does not validate every marketing promise.
Concentration in context
A percentage is useful only when the chemical form, vehicle, pH, stability and studied use are also considered.
Safety stays visible
Irritation, allergy potential, pregnancy guidance and professional-help limits are not hidden beneath benefit claims.
Commercial independence
Brands may advertise, but they cannot buy rankings, conclusions, edits or removal of criticism.
Ingredient library FAQ
Common questions before choosing an active.
These answers help you interpret ingredient guides without turning a simple routine into a chemistry project.
Does a higher percentage always work better?
No. Higher concentrations can increase irritation without producing a proportionally better result. Formula stability, vehicle, pH and tolerability often matter as much as the number on the label.
Can I combine several active ingredients?
Sometimes, but introducing one change at a time makes irritation easier to identify. A routine that is simple enough to follow consistently is usually more useful than an aggressive stack of actives.
What does an evidence badge mean?
The badge reflects the overall quality and relevance of evidence for the guide’s central skincare uses. Individual claims inside each guide may still receive different evidence assessments.
Are ingredient guides a substitute for medical advice?
No. They support product decisions and general education. Persistent, severe, painful or rapidly changing skin concerns should be assessed by a qualified healthcare professional.
Continue your research
Move from ingredients to better decisions.
Use the wider Skin Candid library to connect an ingredient with your concern, routine and product choice.