Allium cepa is the well-known onion plant, widely cultivated around the world for its edible bulb. Beyond its culinary uses, onion has a long history in traditional remedies for skin and hair issues including scalp and wound care. Recent cosmetic ingredient databases list “Allium cepa bulb extract” (INCI: Allium cepa bulb extract) as an accepted functional botanical.
Key Functional Attributes & Mechanisms
What makes onion-bulb extract interesting in formulations are several core scientific/functional features:
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Antioxidant & anti-inflammatory compounds: Onion contains flavonoids (quercetin, kaempferol), sulfur-based compounds and phenolics which contribute to scavenging free radicals, helping protect cells from oxidative stress.
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Antimicrobial and antifungal activity: Some data associate onion extract with antibacterial and antifungal effects, making it helpful in formulations targeting scalp concerns, blemishes or microbial imbalance.
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Hair follicle & scalp support: Onion extract has been used in hair-care to strengthen hair, support root health, reduce fall and improve scalp condition. The high sulfur content in onion is linked to keratin production, which is key for hair strength and integrity.
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Scar and post-injury skin appearance: In skin care, onion extract is especially noted for its role in improving cosmetic appearance of scars and skin-texture after injury/surgery, likely due to its anti-inflammatory, collagen-modulating and antioxidant actions.
Thus, in a cosmetic or personal-care formulation, Allium cepa bulb extract can serve as a multi-functional botanical: antioxidant protector, antimicrobial adjunct, hair-growth/scalp supporter, and skin-appearance enhancer.
Applications & Benefits in Skin & Hair Care
Because of those attributes, this ingredient finds use in both hair-care (shampoos, scalp serums, hair oils) and skin-care (scar gels, moisturisers, acne treatments) with benefits such as:
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Scalp & hair health: By supporting keratin structure and offering antioxidant/anti-microbial support, onion extract helps in reducing hair breakage, improving resilience, promoting stronger roots and healthier hair growth. For example, a supplier lists insertion of onion extract powder to help stimulate scalp circulation, reduce hair fall and strengthen roots.
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Scalp inflammation & microbial balance: Useful for soothing an irritated scalp, controlling fungal/yeast or microbial over-growth conditions, thereby improving overall scalp condition and indirectly hair growth/quality.
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Scar improvement & skin texture smoothing: Cosmetic studies point to onion extract gel improving appearance of new scars (less redness, improved smoothness), by modulating inflammation and possibly collagen turnover.
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General skin antioxidation & soothing: The flavonoids and sulfur compounds help in neutralising oxidative stress due to environment, UV, or internal factors — which in turn supports skin firmness, tone, and radiance.
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Multi-benefit formulation positioning: The fact that onion is natural/plant-derived also supports marketing claims of botanical, clean-beauty, multifunctional hair/skin support.
Formulation Notes & Considerations
When incorporating Allium cepa bulb extract, a few practical notes:
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As per INCI lists (e.g., INCIDecoder) the ONION extract classification is “skin conditioning”.
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Typical formats: water-soluble extracts (hydroalcoholic or aqueous extracts of onion bulb), or seed oil/seed extract forms for hair oils. Extraction method affects flavour/odor, potency of sulfur compounds, and color/scent profile.
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In hair-care, higher sulfur compounds may smell strong; thus formulators often include odour-reduction or masking systems.
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Because onion extract has a strong botanical profile, pairing with active ingredients like peptides (for hair), ceramides (for skin barrier), or glycolic/enzymatic exfoliants (for scar texture) can enhance outcomes.
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Usage levels: while specific data vary, one supplier suggests onion extract powder for hair at 0.5-5% in aqueous phase for scalp treatments.
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Safety: According to the Environmental Working Group (EWG) Skin Deep database, Allium cepa bulb extract is rated as low hazard across cancer, allergies/immunotoxicity, developmental/reproductive toxicity when used in cosmetics.
Safety & Usage
Topically, Allium cepa extracts and oils are generally considered safe when used appropriately. However some caveats:
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As with all botanicals, individuals with onion/allium sensitivities should patch-test.
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While onion extract supports hair/scalp/negligible skin benefits, it is not a substitute for medical treatments (e.g., hair loss from hormonal causes, deep scarring requiring dermatological intervention).
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In hair-care, base formulation and delivery matter (e.g., leave-on vs rinse-off, scalp vs lengths).
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Odor and color may need to be managed if extract retains strong sulphur smell or pigmentation.
Properties
Anti-oxidant, Wound healing, Scar reducer
INCI Name
Allium cepa Bulb Extract
