Ingredient review
Ammonium Thiocyanate
INCI: AMMONIUM THIOCYANATE
Ammonium thiocyanate is a synthetic salt used in professional hair waving and straightening products; it is not a skin-conditioning ingredient and can be irritating if misused.
In plain English
Ammonium thiocyanate is a chemical salt that helps break and reform hair bonds during perms or straightening treatments. It is not something you apply for skin benefits—it's a processing aid that works on hair structure. Because it can be irritating, it's typically used only in professional salon products and requires careful handling.
Quick decision guide
Read the cautions before using
Ammonium Thiocyanate can be useful, but watch for some irritation potential.
Plain-English read
Treat this as a practical screening step before you compare products that contain this ingredient.
- Step 1Start with the score, then check the irritation and clogging risk before judging Ammonium Thiocyanate.
- Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
- Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.
Score terms in plain English
Irritation risk
moderateCan bother some users, especially with frequent use, damaged skin, or strong companion ingredients.
Clogging risk
lowLess likely to feel heavy or contribute to clogged pores for most skin types.
Evidence level
moderateThere is useful support, but formula details and claim strength still matter.
What it is
A synthetic ammonium salt of thiocyanic acid, used as a reducing agent in hair waving and straightening formulations to break disulfide bonds in hair keratin.
How it works
In hair waving or straightening, ammonium thiocyanate acts as a reducing agent that breaks disulfide bonds in hair keratin, allowing the hair to be reshaped. After the hair is set in the desired form, an oxidizing agent (neutralizer) reforms the bonds to lock in the new shape.
Pros
Effective for reshaping hair
Ammonium thiocyanate reliably breaks hair bonds, allowing for long-lasting curls or straightening when used correctly by a professional.
Lower pH alternative
Compared to some traditional waving agents, it can work at a slightly lower pH, which may be less damaging to hair cuticles.
Cons and cautions
Irritation risk
Direct contact with skin or scalp can cause redness, stinging, or irritation, especially if left on too long or used on compromised skin.
Not for daily use
This is a strong chemical processing aid, not a conditioning ingredient. It should never be used in leave-on or rinse-off skincare products.
Best for
- Individuals seeking professional salon perms or straightening treatments
- People with resilient hair that can tolerate chemical processing
Use caution if
- Those with sensitive scalp, eczema, or broken skin
- Pregnant or nursing individuals (due to lack of safety data for systemic exposure)
Usage tips
Safety summary
Ammonium thiocyanate is considered safe for professional use in hair waving and straightening when used as directed and rinsed off promptly. However, it can cause moderate skin and eye irritation, and there is limited data on long-term or repeated exposure. It should not be used in leave-on skincare products.
Research notes
Research on ammonium thiocyanate in cosmetics is limited. Most safety data comes from industrial and occupational exposure studies, which indicate irritation potential. No peer-reviewed studies confirm its safety for leave-on or daily-use cosmetic applications.
Common label clues
- Typical concentration
- Typically 1–5% in professional-use hair waving formulations
- Regulatory status
- In the US, ammonium thiocyanate is not specifically restricted in cosmetics but is subject to general safety requirements. The EU CosIng database lists it as a hair waving or straightening ingredient. Professional use is typical due to irritation potential.
- Common uses
- Permanent hair waving, Hair straightening, Chemical depilatories
- Environmental note
- Thiocyanate compounds can be toxic to aquatic life if released in large quantities. Proper disposal of salon waste is important.
Good to know
- Ammonium thiocyanate is not a common ingredient in over-the-counter beauty products; it is mostly found in professional salon formulations.
- It may be listed on labels as 'ammonium sulfocyanate' or 'ammonium rhodanide'.
Common questions
What is Ammonium Thiocyanate in beauty products?
Ammonium thiocyanate is a chemical salt that helps break and reform hair bonds during perms or straightening treatments. It is not something you apply for skin benefits—it's a processing aid that works on hair structure. Because it can be irritating, it's typically used only in professional salon products and requires careful handling.
What does Ammonium Thiocyanate do in a beauty product?
In hair waving or straightening, ammonium thiocyanate acts as a reducing agent that breaks disulfide bonds in hair keratin, allowing the hair to be reshaped. After the hair is set in the desired form, an oxidizing agent (neutralizer) reforms the bonds to lock in the new shape.
Is Ammonium Thiocyanate safe for most people?
Ammonium thiocyanate is considered safe for professional use in hair waving and straightening when used as directed and rinsed off promptly. However, it can cause moderate skin and eye irritation, and there is limited data on long-term or repeated exposure. It should not be used in leave-on skincare products.
Who should be careful with Ammonium Thiocyanate?
Those with sensitive scalp, eczema, or broken skin Pregnant or nursing individuals (due to lack of safety data for systemic exposure)
Research sources
Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.