Sodium Hydroxide is a strong alkaline chemical used in skincare products primarily as a pH buffer to neutralize acids and adjust the product's pH to safe levels for skin. It is not an active skincare ingredient and appears only in trace amounts in finished products.
Potential concerns
In concentrated form, sodium hydroxide is caustic and can cause severe chemical burns; however, in cosmetic products it is diluted and pH-buffered to safe levels
Undiluted or highly concentrated sodium hydroxide should never contact skin directly
Science: The provided research discusses sodium hydroxide only in a specialized medical context (10% solution for surgical cauterization of ingrown toenails), which is not relevant to cosmetic skincare use. In properly formulated skincare products, sodium hydroxide is used in minimal concentrations solely for pH adjustment and is considered safe by regulatory bodies including the FDA and EU.
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.
Purified water is water that has been filtered and processed to remove impurities, minerals, and contaminants. In skincare products, it serves as the primary base ingredient that delivers active compounds to your skin and helps maintain hydration.
Benefits
Acts as a hydrating base for skincare formulations
Helps dissolve and deliver active ingredients
Provides a clean, neutral foundation free from tap water impurities
Science: Purified water is a well-established, inert ingredient with an excellent safety profile in topical skincare. Research referenced here examined enhanced water formulations (oxygen nano-bubble water and ozone water) rather than standard purified water itself, but found purified water to be safe as a control baseline.
Methylparaben is a preservative used in skincare and cosmetic products to prevent bacterial and fungal growth, extending shelf life. It's one of the most commonly used preservatives in the beauty industry and has been approved for use in cosmetics across most regulatory regions.
Benefits
Prevents microbial contamination and product spoilage
Allows products to remain safe and effective throughout their shelf life
Cost-effective preservation at low concentrations
Potential concerns
Classified as a potential carcinogen in recent literature reviews; however, regulatory bodies consider approved concentrations safe
Some studies suggest parabens may have weak estrogenic activity, though real-world risk at cosmetic-use levels remains debated
May cause contact sensitivity or allergic reactions in individuals with paraben sensitivity
Science: A 2023 review identified methylparaben among potential carcinogenic substances in analyzed cosmetics, though the authors note these are used 'within allowable range of established concentrations.' Current EU and regulatory approval suggests approved concentrations are considered safe for consumers, but long-term exposure studies at cosmetic levels remain limited.
