What Is Sodium Thioglycolate?
Sodium thioglycolate, also known as sodium mercaptoacetate, is the sodium salt of thioglycolic acid. This small sulfur-containing molecule is water soluble and has a distinctive sulfur scent. It was first explored in the 1940s when chemists searched for gentler alternatives to traditional hair removal and perming agents. Over time its strong yet controllable reducing power made it a regular in professional salon products and later in at-home formulas.
Commercial production begins with chloroacetic acid which is reacted with sodium hydrosulfide to create sodium thioglycolate. The resulting solution is purified, adjusted to the desired concentration and then blended into finished cosmetic bases.
You will most often find sodium thioglycolate in depilatory creams, hair removal sprays, professional perm and hair straightening lotions, callus-softening foot masks and some antioxidant-boosted skincare treatments where its reducing action helps protect other ingredients.
Sodium Thioglycolate’s Cosmetic Benefits/Uses
This ingredient offers several functional benefits that formulators rely on
- Antioxidant – Helps neutralize oxygen-based degradation of other ingredients which can keep a product stable and extend shelf life
- Depilatory – Breaks the disulfide bonds in keratin so hair softens and can be wiped away at the skin’s surface providing quick, pain-free hair removal
- Hair Waving Or Straightening – In professional perms or relaxers it reduces hair’s internal bonds allowing strands to be reshaped into curls or smoothed straight before new bonds are set with an oxidizing neutralizer
- Reducing – Acts as a general reducing agent that can alter or stabilize other ingredients making it valuable in specialized treatments beyond hair care
Who Can Use Sodium Thioglycolate
Sodium thioglycolate is generally suitable for normal, combination and oily skin types since it is water soluble and rinses clean without leaving a greasy residue. Those with sensitive or very dry skin may find its keratin-breaking action irritating, especially if a formula is left on longer than directed or used too frequently.
The compound itself is synthetic and not derived from animal sources so products that use it are typically appropriate for vegans and vegetarians. As always it is wise to scan the full ingredient list because some depilatory or perming products pair sodium thioglycolate with animal-derived additives like keratin proteins.
Current research has not linked topical sodium thioglycolate to fetal harm or breastfeeding complications. That said this is not medical advice and anyone pregnant or nursing should review any cosmetic containing the ingredient with their healthcare provider before use.
Sodium thioglycolate does not increase photosensitivity so there is no special need for extra sun protection solely because of its presence, though sunscreen remains important for overall skin health. People with a known sulfur allergy or a history of dermatitis from depilatories should avoid it.
Potential Side Effects/Adverse Reactions
Reactions to topical sodium thioglycolate vary from person to person. The effects listed below are only potential outcomes and are unlikely for most users when the ingredient is correctly formulated and used as directed.
- Irritation – burning, stinging or redness may occur if the product is left on too long or used on already compromised skin
- Contact dermatitis – some individuals may develop an itchy rash or swelling due to sensitivity to the sulfur component
- Allergic reaction – rare cases of hives or difficulty breathing have been reported in people with a severe sulfur or thiol allergy
- Hair weakening or breakage – overprocessing during perms or relaxers can leave strands fragile and prone to snapping
- Unpleasant odor – the natural sulfur smell may linger temporarily on skin or hair and can be bothersome to sensitive noses
If any negative reaction occurs discontinue use immediately rinse the area thoroughly with cool water and seek medical advice if symptoms persist or worsen.
Comedogenic Rating
Sodium thioglycolate has a comedogenic rating of 0. This small water soluble salt rinses off cleanly and leaves no oily residue so it does not block pores or trap sebum.
It is therefore considered suitable for skin that is prone to acne or breakouts. Any blemishes that appear after use are more likely caused by other formula components such as heavy emollients or fragrance.
Keep in mind that the high pH of many depilatory and perm bases can still irritate skin which may indirectly flare acne in sensitive individuals.
Summary
Sodium thioglycolate acts as an antioxidant, depilatory agent, hair waving or straightening aid and general reducing agent. Its reactive sulfur group donates electrons to break disulfide bonds in keratin or to protect vulnerable ingredients from oxidation which is why it excels in hair removal creams, perm lotions and certain preservative systems.
While not a household name it remains a workhorse in professional and over the counter hair removal products and still sees steady demand in salon perm kits. Its presence in mainstream facial skincare is limited so everyday consumers may not encounter it often.
Regulatory reviews find it safe when used as directed yet its potent action means irritation is possible. Patch test any new product containing sodium thioglycolate before full use to make sure your skin tolerates it well.