What Is Ammonium Thioglycolate?
Ammonium thioglycolate, sometimes listed as ammonium mercaptoacetate, is a salt formed from thioglycolic acid and ammonia. The molecule features a sulfur-containing group that has a strong attraction to the disulfide bonds found in hair keratin, which is the key to its cosmetic value. Originally investigated in the 1930s as an alternative to harsher alkaline sulfides used in early cold waves, it gained popularity after World War II when reliable home perm kits hit store shelves. Today manufacturers create the ingredient by neutralizing thioglycolic acid with ammonium hydroxide, then purifying the resulting solution to cosmetic grade.
Thanks to its bond-breaking ability, ammonium thioglycolate appears most often in products aimed at reshaping or removing hair. You will find it in professional perm solutions, at-home hair relaxers, depilatory creams, beard-softening treatments, some callus-softening foot masks and specialty creams that prepare coarse body hair for easier trimming.
Ammonium Thioglycolate’s Cosmetic Benefits/Uses
In formulas, this ingredient serves several roles that center on altering keratin structure or aiding other actives
- Depilatory: By breaking the disulfide bonds that give hair its strength, ammonium thioglycolate allows the visible shaft to weaken and detach from the skin surface. This lets a cream or lotion wipe away unwanted facial or body hair quickly without razor use
- Hair Waving or Straightening: In permanent waves or chemical relaxers, it reduces internal bonds so hair can be reshaped around rods for curls or combed straight. After rinsing, a neutralizer reforms the bonds in the new pattern giving long-lasting style change
- Reducing agent: Beyond hair work, its bond-breaking action can gently soften callused skin or enhance the penetration of other actives by loosening the outer protein layer, improving overall product performance
Who Can Use Ammonium Thioglycolate
Because products containing ammonium thioglycolate are usually rinsed off after a short processing time they are generally suitable for normal, oily and combination skin types. People with very dry or sensitive skin, eczema or broken skin should be cautious as the high pH and sulfur content can provoke stinging or redness.
The ingredient is produced synthetically from basic chemicals and does not rely on animal sources so it is considered acceptable for vegans and vegetarians.
Current safety data do not show specific risks for pregnant or breastfeeding women when the ingredient is used as directed in over the counter depilatories or salon hair-reforming services. That said this is not medical advice and anyone who is pregnant or nursing should run any cosmetic product past a qualified health professional just to be on the safe side.
Ammonium thioglycolate does not make skin more prone to sunburn and it does not interact with UV filters so no special photosensitivity precautions are needed beyond routine daily sunscreen use.
People who have a known allergy to thioglycolic acid salts or a history of sulfhydryl sensitivity should avoid it.
Potential Side Effects/Adverse Reactions
Side effects and reactions to the topical application of ammonium thioglycolate can vary from person to person. The points below cover potential issues and are highly unlikely to be the typical user experience. When the ingredient is included at regulated levels in a well formulated product most users will not notice any adverse effects.
- Skin irritation such as redness, stinging and mild swelling during or shortly after use
- Chemical burn if the product is left on longer than directed or applied to already compromised skin
- Allergic contact dermatitis in individuals sensitized to thioglycolic acid salts or sulfur compounds
- Temporary lingering sulfur smell on skin or hair
- Hair weakening or breakage if overprocessed in waving or straightening services
- Eye irritation or watering if vapors or splashes reach the eye area
If any of these effects occur discontinue use rinse the area thoroughly with cool water and seek medical advice if symptoms persist or worsen.
Comedogenic Rating
Rating: 0 / 5. Ammonium thioglycolate is a water-soluble salt that does not leave an oily or occlusive residue on skin or within follicles, so it has virtually no tendency to clog pores. Because products containing it are rinse-off formulas that remain on the skin or scalp for only a short time, the opportunity for pore blockage is minimal. This makes it generally suitable for people who are prone to acne or breakouts. The only caveat is that high pH and irritation can sometimes trigger secondary blemishes in very sensitive users, although this is rare.
Summary
Ammonium thioglycolate acts as a depilatory, hair-waving or straightening agent and general reducing agent. It performs these jobs by breaking the disulfide bonds in keratin, which weakens hair structure so it can be wiped away or reshaped before a neutralizer reforms the bonds in the desired pattern. The ingredient remains a workhorse in professional perms and relaxers plus at-home depilatory creams, yet it is not as widely talked about as trendier actives because its use is mostly limited to niche hair-removal or hair-reforming products. When used as directed and kept away from compromised skin it is considered safe, with irritation being the main concern if directions are ignored. As with any cosmetic, it is smart to patch test a new product containing ammonium thioglycolate to check personal tolerance before full use.