What Is Isophorone Diamine Sesquimaleate?
Isophorone Diamine Sesquimaleate is a blend of salts formed when maleic acid is reacted with isophorone diamine, a synthetic ingredient originally developed for industrial coatings. Chemists discovered that the resulting salt mixture bonds well to damaged hair, which opened the door for its cosmetic use. Production starts with purified maleic acid and isophorone diamine. Under controlled temperature and pH, the two are combined so the acid neutralizes part of the amine groups, creating a stable salt complex. After filtration and drying, the powder is ready for formulators.
Because it helps smooth and strengthen hair fibers, the ingredient shows up in rinse-off and leave-in products such as shampoos, conditioners, hair masks, bonding treatments and color-protecting serums. You will rarely see it in skin care since its main talent is hair conditioning.
Isophorone Diamine Sesquimaleate’s Cosmetic Benefits/Uses
In hair care formulas this ingredient serves one clear purpose: it conditions the hair. By forming a lightweight film along the cuticle it helps reduce breakage, improve combability and leave strands feeling softer and glossier.
Who Can Use Isophorone Diamine Sesquimaleate
This ingredient is considered gentle enough for all scalp and hair types including dry, oily, color-treated and chemically processed strands. Because it stays on the hair shaft and is rinsed or left on in small amounts, it poses little risk to sensitive skin around the hairline. No specific skin type needs to avoid it unless there is a known allergy to amine-based compounds.
Isophorone Diamine Sesquimaleate is synthesized from maleic acid and isophorone diamine, neither of which is derived from animals, so products using it are typically suitable for vegans and vegetarians. Always check the full ingredient list in case other animal-based additives are present.
Current safety data show no direct concerns for women who are pregnant or breastfeeding when the ingredient is used in rinse-off or leave-in hair products. This is not medical advice and anyone who is pregnant or nursing should review all personal care products with a healthcare professional to be extra safe.
The salt complex does not increase photosensitivity, so it will not make scalp or skin more prone to sunburn.
Potential Side Effects/Adverse Reactions
Reactions to topical Isophorone Diamine Sesquimaleate differ from person to person. The effects listed below are only potential issues and are not expected for most users when the ingredient is properly formulated and used as directed.
- Mild scalp redness or itching
- Stinging if applied to broken or irritated skin
- Rare allergic contact dermatitis in individuals sensitive to diamines
- Eye irritation if the product accidentally drips into eyes
If any of these reactions occur stop using the product and seek medical advice if symptoms persist or worsen.
Comedogenic Rating
Rating: 0 out of 5. Isophorone Diamine Sesquimaleate is water soluble and not oily, so it does not linger in pores or form a greasy film on skin. Its primary action is on the hair shaft rather than the skin, which further lowers any clogging risk. In short, the ingredient is generally fine for people who tend to break out. Because it is often used in rinse-off or low-leave-on levels, its contact time with facial skin is minimal, making pore blockage even less likely.
Summary
Isophorone Diamine Sesquimaleate works as a hair conditioning agent, smoothing cuticles, reducing breakage and adding shine by forming a light protective layer along each strand. It is still a niche ingredient compared to long-standing conditioners like silicones and quats, but formulators are starting to include it in bond-building masks and color care lines for its strengthening effect without heavy build-up. Safety reviews classify it as low risk for irritation when used as directed. While most users tolerate it well, it is always wise to patch test a new product before full use to rule out personal sensitivities.