Ingredient review
Sodium Thiocyanate
INCI: SODIUM THIOCYANATE
Sodium thiocyanate is a synthetic preservative booster with limited safety data; it may cause irritation for sensitive skin and is best avoided in leave-on products.
In plain English
Sodium thiocyanate is a man-made salt that helps preserve cosmetic products by preventing the growth of microbes. It is sometimes added to boost the effectiveness of other preservatives. However, it has limited safety research in skincare, and some studies suggest it can be irritating, especially for people with sensitive skin or thyroid conditions. Because of these concerns, it is more commonly found in rinse-off products like shampoos rather than leave-on creams or serums.
Review score
Safety, usefulness, and evidence
Higher-caution ingredient
The evidence base is still emerging, so marketing claims deserve extra caution.
Main practical flags: irritation is moderate; clogging risk is low.
- Source
- synthetic
- Evidence
- emerging
- Irritation
- moderate
- Clogging risk
- low
Quick decision guide
Read the cautions before using
Sodium 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 Sodium 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
emergingThe ingredient may be promising, but claims should be treated more cautiously.
What it is
Sodium thiocyanate is the sodium salt of thiocyanic acid, a synthetic compound used in cosmetics as a preservative enhancer and stabilizer. It is not naturally derived and is produced through chemical synthesis.
How it works
In a cosmetic formula, sodium thiocyanate works by disrupting the cell membranes of bacteria and fungi, helping to prevent spoilage. It is often used in combination with other preservatives to lower the total preservative concentration needed, which can reduce irritation potential of the overall system. However, its own safety profile is less established than more common preservatives.
Pros
Preservative booster
Sodium thiocyanate helps enhance the effectiveness of other preservatives, potentially allowing for lower overall preservative levels in a product.
Shelf-life extension
It contributes to preventing microbial contamination, which can help keep products stable and safe to use over time.
Cons and cautions
Limited safety data
There is not enough high-quality research on sodium thiocyanate's long-term effects when applied to skin, especially in leave-on products.
Irritation potential
Some users report stinging, redness, or irritation, particularly with sensitive skin or when used in leave-on formulations.
Best for
- People using rinse-off products like shampoo or body wash where exposure is brief
- Those without known thyroid conditions or skin sensitivities
Use caution if
- Individuals with sensitive, reactive, or eczema-prone skin
- People with thyroid disorders or those taking thyroid medication
Usage tips
Safety summary
Sodium thiocyanate has limited safety data in cosmetics. It can cause skin irritation and may interfere with thyroid function if absorbed in significant amounts. It is generally considered safer in rinse-off products at low concentrations, but sensitive individuals and those with thyroid issues should exercise caution.
Research notes
Most available research on sodium thiocyanate focuses on industrial or medical contexts, not cosmetic use. There are no large-scale human studies on its safety in skincare. The Cosmetic Ingredient Review has not published a monograph on this ingredient, so evidence is considered emerging.
Common label clues
- Typical concentration
- Typically used at very low levels, often below 1%
- Regulatory status
- Sodium thiocyanate is not specifically restricted by the FDA for cosmetics, but it is not widely reviewed by safety panels like the Cosmetic Ingredient Review (CIR). Its use is generally accepted at low concentrations in rinse-off products.
- Common uses
- Rinse-off products like shampoos and cleansers, Hair care formulations
- Environmental note
- Sodium thiocyanate is synthetic and may persist in water systems; its environmental impact is not well studied.
Good to know
- Sodium thiocyanate is not a primary preservative but is often used as a 'booster' to support other preservatives.
- It is more common in professional or salon hair products than in everyday skincare.
Common questions
What is Sodium Thiocyanate in beauty products?
Sodium thiocyanate is a man-made salt that helps preserve cosmetic products by preventing the growth of microbes. It is sometimes added to boost the effectiveness of other preservatives. However, it has limited safety research in skincare, and some studies suggest it can be irritating, especially for people with sensitive skin or thyroid conditions. Because of these concerns, it is more commonly found in rinse-off products like shampoos rather than leave-on creams or serums.
What does Sodium Thiocyanate do in a beauty product?
In a cosmetic formula, sodium thiocyanate works by disrupting the cell membranes of bacteria and fungi, helping to prevent spoilage. It is often used in combination with other preservatives to lower the total preservative concentration needed, which can reduce irritation potential of the overall system. However, its own safety profile is less established than more common preservatives.
Is Sodium Thiocyanate safe for most people?
Sodium thiocyanate has limited safety data in cosmetics. It can cause skin irritation and may interfere with thyroid function if absorbed in significant amounts. It is generally considered safer in rinse-off products at low concentrations, but sensitive individuals and those with thyroid issues should exercise caution.
Who should be careful with Sodium Thiocyanate?
Individuals with sensitive, reactive, or eczema-prone skin People with thyroid disorders or those taking thyroid medication
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.