Glycerin is a naturally derived humectant—a ingredient that draws moisture from the air into your skin. It's one of the most widely used and well-studied moisturizing agents in skincare, helping skin feel softer and more hydrated.
Benefits
Attracts and retains moisture in the skin
Improves skin hydration and softness
Helps strengthen skin barrier function
Suitable for most skin types, including sensitive skin
Science: The Cosmetic Ingredient Review Expert Panel concluded glycerin is safe as used in cosmetics across all concentrations. Research shows glycerin effectively improves skin hydration and is well-tolerated with minimal irritation risk. It is also referenced in clinical guidelines for managing inflammatory skin conditions and maintaining skin integrity.
Citric acid is a naturally occurring organic acid commonly used in skincare products as an exfoliant and pH balancer. It belongs to a group of ingredients called alpha-hydroxy acids (AHAs) that help remove dead skin cells from the surface.
Benefits
Gentle exfoliation to improve skin texture and appearance
Helps reduce the appearance of keratosis and acne
Balances product pH to maintain skin compatibility
Potential concerns
Can cause irritation, redness, or sensitivity in some users, especially with prolonged or frequent use
May increase sun sensitivity — sunscreen use is recommended when using AHA products
Not suitable for very sensitive or compromised skin without caution
Science: Citric acid is an established AHA used in cosmetics for superficial peeling and skin appearance improvement, though research emphasizes that caution should be exercised due to potential adverse reactions. It is widely produced industrially and well-established in skincare formulations.
Potassium sorbate is a preservative used in skincare products to prevent the growth of mold, yeast, and some bacteria, helping extend shelf life. It's a salt derived from sorbic acid and is commonly used as a gentler alternative to stronger chemical preservatives.
Benefits
Prevents microbial contamination and mold growth
Generally considered milder than some other preservatives like benzalkonium chloride
Allows products to remain effective longer without refrigeration
Potential concerns
May cause irritation or allergic contact dermatitis in sensitive individuals
Not suitable for preservative-free formulations
Limited effectiveness against some bacteria compared to stronger preservatives
Science: Clinical research suggests potassium sorbate is less damaging to delicate tissues than benzalkonium chloride, making it a preferred alternative preservative in sensitive applications like eye products. However, peer-reviewed safety data specific to topical skincare use in the general population is limited.
Sodium benzoate is a preservative used in skincare products to prevent bacterial and fungal growth, extending shelf life. It's a salt derived from benzoic acid and is one of the most widely used preservatives in cosmetics, skincare, and food products.
Benefits
Prevents microbial contamination and extends product shelf life
Generally effective at low concentrations (0.1-0.5%)
Approved for cosmetic use by major regulatory bodies
Potential concerns
Can cause allergic contact dermatitis in sensitive individuals; identified as an allergen in medical hand cleansers
Recent research suggests long-term oral intake may affect bone health and increase osteoporosis risk, though topical skincare exposure is minimal
Science: Sodium benzoate is well-established as a safe preservative in cosmetics at typical use levels. However, emerging research indicates that chronic systemic intake may interfere with bone metabolism through the FGF2/p38/RUNX2 pathway. For topical skincare use, the exposure and absorption are minimal compared to dietary intake, but individuals with known sensitivities should avoid it.
Pentylene glycol is a lightweight humectant—a ingredient that draws water into the skin to improve hydration and texture. It's commonly used in serums, sunscreens, and moisturizers as a preservative booster and skin-conditioning agent.
Benefits
Improves skin hydration by attracting moisture
Lightweight feel, absorbs quickly without heaviness
Helps preserve product stability and extends shelf life
Potential concerns
Rare contact allergy reported in sensitive individuals
Emerging evidence suggests it may be an uncommon cosmetic allergen—if you have sensitive or reactive skin, patch test first
Science: Safety studies show a high margin of safety at standard use levels (87–671 in adults), with minimal skin penetration due to the ingredient's volatility. However, recent dermatological reports flag pentylene glycol as an emerging contact allergen in some individuals, warranting attention for those with sensitive skin.
Propylene glycol is a lightweight humectant and solvent commonly used in skincare formulations. It helps draw moisture into the skin and improves the texture and spreadability of products.
Benefits
Hydrates skin by attracting and retaining moisture
Enhances product texture and makes formulas easier to apply
Helps active ingredients penetrate the skin more effectively
Improves stability and shelf life of formulations
Potential concerns
May cause contact dermatitis or irritation in sensitive individuals
Can occasionally trigger allergic reactions in susceptible people
High concentrations may feel sticky or heavy on some skin types
Science: Research confirms propylene glycol acts as a penetration enhancer in topical formulations, improving skin uptake of active ingredients. The ingredient is widely studied and considered safe at typical cosmetic concentrations, though individual sensitivity varies.
Sodium Cocoyl Glutamate is a gentle, plant-derived cleanser made from coconut oil and the amino acid glutamate. It removes dirt and oil from skin while maintaining a mild pH, making it suitable for sensitive skin types.
Benefits
Gentle cleansing action
Mild and non-stripping
Suitable for sensitive or reactive skin
Science: Limited peer-reviewed data available for this ingredient. As an amino acid-derived surfactant, it belongs to a class of mild cleansers generally recognized as safe by regulatory bodies and well-tolerated in cosmetic formulations.
Dihydroxyacetone (DHA) is a 3-carbon sugar approved by the FDA as a color additive for sunless tanning products. When applied to skin, it reacts with proteins in the outer layer to produce a temporary brown tan-like color that develops over a few hours.
Benefits
Creates a tan appearance without sun exposure
Temporary effect that washes off with soap and water
Allows customization of tan depth depending on product concentration
Potential concerns
Should not contact eyes, lips, or mucous membranes
Inhalation of spray-tan mist is not FDA-approved and should be avoided
May cause streaking or uneven coloring if not applied evenly
Science: DHA has been used safely in topical tanning products since the 1960s. It works by binding to free amino groups in skin proteins, particularly arginine, to create the brown color. Current research suggests DHA staining may have diagnostic applications in dermatology for identifying skin lesions.
PEG-40 Hydrogenated Castor Oil is a synthetic ingredient made by chemically modifying castor oil with polyethylene glycol. It functions as an emulsifier and solubilizer, helping to blend oils and water-based ingredients together and improve the texture and stability of skincare formulations.
Benefits
Helps create smooth, stable product textures
Improves ingredient mixing in formulations
Enhances absorption of other active ingredients
Science: Scientific review data confirm PEG-40 hydrogenated castor oil is safe for cosmetic use at concentrations up to 100%, with no documented toxicity concerns for topical application. The ingredient has a well-established safety profile supported by multiple regulatory and peer-reviewed assessments.
Hydroxypropyl Methylcellulose (HPMC) is a plant-derived thickening and film-forming agent commonly used in skincare products to improve texture and create a smooth application. It helps products spread evenly on skin and can form a protective layer on the surface.
Benefits
Improves product texture and spreadability
Creates a lightweight, non-greasy feel
Forms a protective moisture barrier on skin
Science: Limited peer-reviewed data available specifically for HPMC in topical skincare applications. The ingredient is widely used in pharmaceutical and cosmetic formulations and has a strong safety history. The provided research focuses on oral and injectable delivery systems rather than topical skincare use.
Erythrulose is a naturally derived sugar that works as a self-tanning agent. Like DHA (dihydroxyacetone), it reacts with amino acids in your skin to create a brown color, but it typically develops more slowly and may last slightly longer than DHA alone.
Benefits
Creates a gradual, natural-looking tan without sun exposure
Often used alongside DHA to extend tan duration and improve color evenness
Generally well-tolerated with low irritation potential
Semi-permanent color that fades as skin naturally sheds dead cells
Potential concerns
May cause contact dermatitis or allergic reactions in sensitive individuals
Can cause unwanted pigmentary changes or streaking if not applied evenly
Provides no UV protection—sunscreen use is still essential
Science: Erythrulose is used in approximately 38% of commercial self-tanning products, typically combined with DHA. It works through the same Maillard reaction mechanism as DHA, producing brown pigments (melanoidins) that deposit in the outer skin layer. Clinical data on adverse effects show self-tanners overall have a low incidence of skin reactions (roughly 2%), though contact dermatitis remains a possible concern in susceptible individuals.
Sodium metabisulfite is a preservative and antioxidant used in skincare to prevent product spoilage and oxidation. It helps extend shelf life by protecting formulations from degradation caused by air and light exposure.
Benefits
Preserves product stability and extends shelf life
Prevents oxidation of other ingredients
Approved for cosmetic use at standard concentrations
Potential concerns
May cause irritation or allergic reactions in sensitive individuals, particularly those with sulfite sensitivities
Can trigger reactions in people with asthma or sulfite allergies
Not typically recommended for products applied to sensitive facial skin
Science: The Cosmetic Ingredient Review Expert Panel confirmed sodium metabisulfite is safe in cosmetic formulations at typical use concentrations (2023). However, research indicates it can affect cellular ion channels at higher concentrations; safety depends on the low levels used in skincare products.
