What Is Ammonium Thiolactate?
Ammonium thiolactate, also listed on ingredient labels as ammonium 2-mercaptopropionate, is the ammonium salt of thiolactic acid. Chemically it contains a sulfur-bearing thiol group and a small lactate backbone, giving it a distinctive mild sulfur scent and strong reducing power. The ingredient is produced by neutralizing thiolactic acid with ammonium hydroxide, then purifying the salt to a cosmetic-grade powder or solution.
Thiolactic compounds caught the beauty industry’s attention in the mid-20th century when chemists were searching for gentler alternatives to thioglycolic acid in hair removal and perming solutions. Ammonium thiolactate offered comparable performance with a slightly less pungent odor and lower irritation risk, so it became a staple in professional salon formulas and later in at-home kits.
Today you will most often find ammonium thiolactate in depilatory creams, hair-waving or straightening lotions, leave-on exfoliating lotions and specialty foot or hand treatments where controlled keratin breakdown is useful. Its ability to weaken the bonds in keratin makes it valuable wherever softening or reshaping hair or calloused skin is desired.
Ammonium Thiolactate’s Cosmetic Benefits/Uses
In topical products this ingredient brings several targeted benefits:
- Depilatory: Breaks the disulfide bonds in hair shafts so the hair can be wiped or rinsed away at the skin’s surface leading to smoother skin for several days
- Hair waving or straightening: Softens and reshapes internal keratin bonds allowing curls to be set or relaxed during salon or at-home treatments, helping styles last until hair regrows
- Reducing agent: Acts as a mild chemical reducer in formulations, helping other actives penetrate by weakening surface keratin and improving overall product performance
Who Can Use Ammonium Thiolactate
This ingredient can suit most skin types, particularly normal oily and thick or calloused skin that benefits from its softening effect. People with very dry or sensitive skin may find it too strong because its reducing action can thin the outer layer and increase stinging or tightness. Anyone with open cuts or inflamed conditions such as eczema should avoid it until skin has healed.
Ammonium thiolactate is made from synthetic sources so it is appropriate for vegans and vegetarians. No animal-derived materials are needed in its production.
Current research has not flagged specific risks for pregnant or breastfeeding women when the ingredient is used at cosmetic levels. Still this is not medical advice and anyone who is pregnant or nursing should discuss any new skincare product with a doctor first to be safe.
The ingredient itself does not create photosensitivity. That said depilatory or callus-softening treatments can leave fresh skin more exposed so daily sunscreen is wise after use.
Potential Side Effects/Adverse Reactions
Responses to topical ammonium thiolactate differ from person to person. The points below list potential but uncommon side effects. When products are formulated and used as directed most people experience smooth trouble-free results.
- Stinging or burning during application
- Temporary redness or swelling
- Dryness or flaking a day or two after use
- Unpleasant sulfur odor lingering on skin or hair
- Allergic contact dermatitis presenting as rash or itching
- Blistering or chemical burn if left on longer than instructions specify
- Increased irritation when layered with strong acids or retinoids
If any of these reactions occur stop using the product immediately and seek guidance from a healthcare professional
Comedogenic Rating
Rating: 1/5 Ammonium thiolactate is water-soluble and does not contain heavy oils or waxes that typically clog pores. While its keratin-softening action can momentarily thin the outer skin layer, it does not leave a residue that traps sebum or debris, keeping the risk of blocked pores low. Skin that is already inflamed or broken may react with temporary redness, but true comedones are unlikely.
Suitable for acne-prone users in most cases, though formulas that pair it with occlusive emollients could change the overall pore-clogging potential, so check the full ingredient list.
No notable interactions with common acne medications beyond possible additive irritation when combined with strong exfoliants.
Summary
Ammonium thiolactate works as a depilatory, hair-waving or straightening agent and general reducing agent. It breaks sulfur bonds in keratin, allowing unwanted hair to wipe away, curls to reform or calloused skin to soften after short contact times. This chemical flexibility keeps it popular in professional salon products and a modest number of at-home creams and lotions, although it has never reached the household-name status of thioglycolic acid.
Used at cosmetic concentrations it is considered safe for healthy skin when directions are followed. Irritation is possible if left on too long or combined with other strong actives, so a small patch test is wise any time you try a new formula that features this ingredient.