What Is Lysine Carboxymethyl Cysteinate?
Lysine Carboxymethyl Cysteinate is a compound made by pairing two naturally occurring building blocks of protein: DL-lysine and S-carboxymethyl-L-cysteine in a one-to-one ratio. When these amino acids are joined they form a salt that is water soluble and easy to work with in cosmetic formulas.
The ingredient first appeared in professional hair salons in the 1960s as chemists searched for gentler ways to reshape hair without the harsh odor and irritation linked to earlier perm solutions. Because it could help break and reform the bonds inside hair fibers at a milder pH, it soon became a staple in wave and straightening lotions. Over time formulators noticed its smoothing and hydrating feel on skin too, so it made its way into creams and serums aimed at softening and conditioning.
Manufacturing begins with plant-derived glucose that is fermented to produce DL-lysine. In a separate step L-cysteine is reacted with chloroacetic acid to add the carboxymethyl group. The two purified amino acids are then blended under controlled temperature and pH to create the final crystalline powder. The finished material is stable, has low odor and dissolves quickly in water-based systems.
Today Lysine Carboxymethyl Cysteinate shows up in a wide range of products such as at-home perm kits, chemical straighteners, anti-frizz masks, leave-in conditioners, reparative shampoos, lightweight moisturizers, soothing after-shave balms and skin-conditioning hand creams.
Lysine Carboxymethyl Cysteinate’s Cosmetic Benefits/Uses
Formulators rely on this versatile amino acid complex for the following reasons:
- Hair waving or straightening – helps loosen and reform disulfide bonds inside the hair shaft so stylists can create long-lasting curls or sleek straight looks with less damage, reduced odor and improved shine
- Skin conditioning – draws moisture to the surface, leaves a silky feel and supports the skin barrier which can make lotions, creams and serums feel smoother and more comforting
Who Can Use Lysine Carboxymethyl Cysteinate
This amino acid salt is generally considered suitable for all skin and hair types, including dry, oily, combination and mature skin, because it is water soluble and has a low risk of clogging pores or leaving a heavy residue. People with extremely sensitive or compromised skin or scalp conditions may want to start with a lower-strength formula, as any bond-altering ingredient can cause discomfort if the barrier is already impaired.
The raw materials come from plant fermentation processes and contain no animal-derived substances, so products that rely on this ingredient can be formulated to meet vegan and vegetarian standards. Always check the finished product label for any added animal-based additives just in case.
Lysine Carboxymethyl Cysteinate has no known hormonal activity and is not absorbed systemically in meaningful amounts when used topically, so it is not expected to pose a specific risk to women who are pregnant or breastfeeding. That said, this is not medical advice and anyone who is expecting or nursing should ask a qualified healthcare professional before introducing new hair or skincare products.
The molecule is not photo-reactive and does not increase sensitivity to sunlight, so extra sun precautions beyond daily sunscreen are not required solely because of this ingredient.
Potential Side Effects/Adverse Reactions
Responses to topical Lysine Carboxymethyl Cysteinate differ among individuals. The points below outline potential, though uncommon, side effects. When the ingredient is correctly formulated most users will not encounter these issues.
- Transient scalp or skin tingling especially during hair waving or straightening services
- Mild redness or irritation on very sensitive skin when used in leave-on products
- Allergic contact dermatitis in people allergic to one of the amino acid components
- Eye irritation if the solution accidentally drips or splashes into the eyes
- Hair dryness or brittleness if left on longer than directed in chemical styling treatments
If any unwanted reaction occurs stop using the product and seek advice from a medical professional or dermatologist.
Comedogenic Rating
Rating: 0/5 – Lysine Carboxymethyl Cysteinate is a highly water-soluble amino acid salt with no oily or waxy residues, so it does not linger in pores or create the kind of film that can trap sebum and dead skin cells.
Because of this zero rating it is considered suitable for people who are prone to acne or breakouts.
In formulas that also contain heavy oils, butters or silicones the overall product could still feel occlusive even though this specific ingredient is not the culprit, so always look at the full ingredient list when assessing pore-clogging potential.
Summary
Lysine Carboxymethyl Cysteinate works as a gentle bond-altering agent in perm and straightening lotions and as a skin-softening humectant in creams, serums and after-shave products. It reshapes hair by loosening and reforming disulfide links within the fiber while its amino acid structure attracts water and smooths the cuticle or skin surface.
Outside professional salon circles the ingredient remains somewhat niche though it pops up in select anti-frizz masks and lightweight moisturizers for its mildness and quick rinse feel.
Overall safety is high: it is vegan friendly, non-comedogenic, non-phototoxic and rarely irritating when used as directed. As with any new cosmetic, patch test first to be sure your individual skin agrees with the formula.