Lactulose is a gentle sugar-derived humectant that also acts as a prebiotic, helping to support a balanced skin microbiome without irritation.
Irritation
low
Source
semi-synthetic
Beauty ingredient research
Browse the review database to understand what an ingredient is, what it does in a beauty formula, when it is useful, and when it deserves caution across skincare, haircare, bodycare, makeup, and more.
20769
Reviewed ingredients
524
Low-concern standouts
2884
Need usage caution
Lactulose is a gentle sugar-derived humectant that also acts as a prebiotic, helping to support a balanced skin microbiome without irritation.
Irritation
low
Source
semi-synthetic
A gentle, mineral-rich seaweed extract that helps hydrate and calm the skin without clogging pores.
Irritation
low
Source
natural
A nutrient-rich seaweed extract that hydrates, soothes, and protects the skin with antioxidants, ideal for dry or sensitive skin types.
Irritation
low
Source
natural
A gentle seaweed powder that helps hydrate and calm the skin while providing antioxidant protection.
Irritation
low
Source
natural
A gentle, mineral-rich seaweed extract that hydrates and soothes the skin, ideal for sensitive or dry types.
Irritation
low
Source
natural
A gentle seaweed extract that hydrates and soothes skin, but its benefits are mostly backed by traditional use and limited clinical studies.
Irritation
low
Source
natural
A gentle, mineral-rich seaweed extract that hydrates and soothes skin, ideal for sensitive or dry types.
Irritation
low
Source
natural
A gentle, nutrient-rich seaweed extract that hydrates and soothes the skin, with antioxidant benefits to help protect against environmental stress.
Irritation
low
Source
natural
A gentle, synthetic amino-acid derivative that helps reinforce the skin’s moisture barrier and improve hydration.
Irritation
low
Source
synthetic
A gentle, plant-based humectant that helps hydrate and soothe the skin, with antioxidant benefits.
Irritation
low
Source
natural
A gentle seaweed powder that helps hydrate and calm the skin, suitable for most skin types.
Irritation
low
Source
natural
Leucine is a gentle amino acid that supports skin hydration and barrier health, making it a safe addition to most routines.
Irritation
low
Source
natural
A gentle, probiotic-based ingredient that helps hydrate and strengthen the skin barrier.
Irritation
low
Source
biotech
Levan is a gentle, biotech-derived humectant that helps hydrate and soothe skin while forming a lightweight protective film.
Irritation
low
Source
biotech
A gentle sugar-based blend that hydrates and helps form a protective layer on skin, suitable for most skin types.
Irritation
low
Source
natural
A gentle, hydrating botanical water that can replace plain water in formulas, offering mild soothing and antioxidant benefits.
Irritation
low
Source
natural
Lithium chloride is a synthetic salt with humectant properties, but it is rarely used in mainstream skincare due to potential irritation and limited research on cosmetic benefits.
Irritation
moderate
Source
synthetic
Lotus flower water is a mild, hydrating botanical water that soothes skin and adds a subtle floral scent, but its benefits beyond basic moisture are not strongly backed by research.
Irritation
low
Source
natural
A gentle, antioxidant-rich water that hydrates and soothes the skin, ideal for sensitive or dry types.
Irritation
low
Source
natural
A gentle, plant-derived humectant that helps hydrate and calm the skin, though research is still emerging.
Irritation
low
Source
natural
Luffa fruit water is a mild, plant-derived hydrator that can soothe and refresh skin, but it has limited research and is not a powerhouse active.
Irritation
low
Source
natural
Lychee fruit juice is a gentle, water-based ingredient that adds light hydration and antioxidant protection, but its benefits are not as well-studied as more common fruit extracts.
Irritation
low
Source
natural
Lysine is a gentle amino acid that helps hydrate and support the skin's natural barrier, making it a safe addition to most routines.
Irritation
low
Source
natural
Lysine Aspartate is a mild amino-acid salt that helps attract moisture to the skin and supports a healthy barrier, making it a gentle option for most skin types.
Irritation
low
Source
semi-synthetic
Magnesium Aspartate is a gentle, hydrating mineral salt that helps support skin barrier function and soothe irritation.
Irritation
low
Source
semi-synthetic
A gentle, water-loving ingredient that hydrates and calms the skin, ideal for sensitive or irritated skin types.
Irritation
low
Source
semi-synthetic
Magnesium citrate is a gentle, water-soluble salt that can help exfoliate and hydrate skin without the irritation of stronger acids.
Irritation
low
Source
synthetic
A gentle humectant that pulls moisture into the skin and may help calm irritation, but research is still limited.
Irritation
low
Source
synthetic
A gentle, hydrating magnesium salt that supports skin barrier function without clogging pores.
Irritation
low
Source
synthetic
Malt extract is a gentle, natural humectant that helps hydrate and soothe the skin, making it a good choice for sensitive or dry skin types.
Irritation
low
Source
natural
Maltitol is a gentle humectant that helps hydrate skin and improve product texture, but it offers no unique advantage over more common alternatives like glycerin.
Irritation
low
Source
semi-synthetic
A mild, hydrating exfoliant ideal for sensitive skin, offering gentle surface renewal without the sting of stronger acids.
Irritation
low
Source
natural
Maltodextrin is a gentle, sugar-derived ingredient that helps products feel smooth and slightly hydrating without clogging pores.
Irritation
low
Source
natural
A mild, sugar-based humectant that pulls water into the skin without stickiness, making it a great alternative to glycerin for lightweight hydration.
Irritation
low
Source
semi-synthetic
Maltose is a gentle, natural humectant that helps attract and hold moisture in the skin without irritation or clogging pores.
Irritation
low
Source
natural
A gentle, plant-based amino acid blend that helps hydrate and support the skin barrier, though research is still emerging.
Irritation
low
Source
natural
Mannan is a gentle, plant-derived sugar that helps hydrate and soothe skin by forming a protective film.
Irritation
low
Source
natural
Mannitol is a gentle, water-binding sugar alcohol that helps hydrate skin and offers mild antioxidant protection without irritation.
Irritation
low
Source
natural
Mannose is a gentle sugar humectant that helps hydrate skin by attracting moisture, with some research suggesting it may support collagen production.
Irritation
low
Source
natural
A gentle, natural humectant that hydrates and soothes skin without clogging pores, ideal for sensitive and dry skin types.
Irritation
low
Source
natural
A gentle, biotech-derived ferment that may help hydrate and support the skin barrier, but research is still early.
Irritation
low
Source
biotech
Mealworm larva extract is an emerging, sustainable ingredient with potential moisturizing and antioxidant benefits, but research in human skincare is very limited.
Irritation
low
Source
natural
Melibiose is a gentle sugar humectant that helps hydrate the skin and may support a healthy skin microbiome, making it a promising alternative to traditional humectants.
Irritation
low
Source
natural
Menthyl PCA offers a gentle, long-lasting cooling sensation without the strong minty odor of menthol, while also helping to hydrate the skin.
Irritation
low
Source
semi-synthetic
A gentle red algae extract that helps hydrate and calm the skin, though research is still emerging.
Irritation
low
Source
natural
Methoxy PEG-10 is a gentle, water-attracting polymer that helps keep skin hydrated and improves product texture, but it is synthetic and may be a concern for those avoiding PEGs.
Irritation
low
Source
synthetic
A synthetic humectant that helps dissolve other ingredients and retain moisture, but offers no unique benefits over gentler alternatives.
Irritation
low
Source
synthetic
A gentle, water-binding ingredient that helps keep products stable and skin hydrated, but its synthetic origin may not appeal to everyone.
Irritation
low
Source
synthetic
A gentle, water-attracting polymer that helps keep skin hydrated without clogging pores, but may not suit those avoiding all PEGs.
Irritation
low
Source
synthetic
A synthetic humectant that helps keep skin hydrated and improves product texture, but may be less eco-friendly due to its PEG origin.
Irritation
low
Source
synthetic
A gentle, sugar-based humectant that hydrates without stickiness, suitable for most skin types including sensitive skin.
Irritation
low
Source
semi-synthetic
A gentle, synthetic amino acid derivative that may help hydrate and support the skin barrier, but research is still emerging.
Irritation
low
Source
synthetic
A mild, non-sticky humectant that pulls water into the skin, making it a great alternative to glycerin for those who dislike tackiness.
Irritation
low
Source
semi-synthetic
A gentle, synthetic amino acid that helps hydrate and condition skin, but research on its benefits is still limited compared to more established humectants.
Irritation
low
Source
synthetic
A gentle synthetic humectant that helps hydrate skin without the sticky feel of glycerin, making it a good option for lightweight formulas.
Irritation
low
Source
synthetic
Methyl lactate is a mild humectant that helps hydrate skin without the sting often associated with pure lactic acid, making it a good option for sensitive skin.
Irritation
low
Source
semi-synthetic
A synthetic humectant that pulls moisture into the skin, but research on its long-term effects is still emerging.
Irritation
low
Source
synthetic
A synthetic humectant that helps skin retain moisture, but research on its long-term effects is still limited.
Irritation
low
Source
synthetic
A lightweight, low-irritation humectant that helps products feel silky and can boost preservative power without adding stickiness.
Irritation
low
Source
synthetic
Methylserine is a gentle, water-attracting amino acid derivative that helps hydrate and condition the skin, but research on its long-term benefits is still limited.
Irritation
low
Source
synthetic