Ingredient review

Tris(Hydroxypropyl) Hexahydrotriazine

INCI: TRIS(N-HYDROXYPROPYL) HEXAHYDROTRIAZINE

A gentle synthetic preservative booster that helps keep your products fresh without the harshness of traditional preservatives.

beautyskincarepreservative

In plain English

This ingredient is a man-made preservative booster. It works by slowly releasing tiny amounts of formaldehyde over time to stop bacteria and mold from growing in your skincare products. The amount released is very small and considered safe at the levels used in cosmetics. It's often added to help other preservatives work better, so less of each is needed overall.

Review score

Safety, usefulness, and evidence

3.8Good
3.8/ 5

Potentially useful with some tradeoffs

The evidence base is useful, but some claims depend heavily on the formula.

Risk flags are low for most users, though the finished product can still irritate.

Source
synthetic
Evidence
moderate
Irritation
low
Clogging risk
low
How reviews are scored

Quick decision guide

Useful, but context matters

Tris(Hydroxypropyl) Hexahydrotriazine is generally a lower-concern ingredient when the full formula suits your skin.

Plain-English read

Treat this as a practical screening step before you compare products that contain this ingredient.

  1. Step 1Start with the score, then check the irritation and clogging risk before judging Tris(Hydroxypropyl) Hexahydrotriazine.
  2. Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
  3. 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

low

Less likely to sting, burn, or bother most users, though sensitive skin can still react.

Clogging risk

low

Less likely to feel heavy or contribute to clogged pores for most skin types.

Evidence level

moderate

There is useful support, but formula details and claim strength still matter.

What it is

A synthetic heterocyclic compound derived from formaldehyde and an amino alcohol. It acts as a formaldehyde-releasing preservative, meaning it breaks down slowly to release formaldehyde, which kills microbes.

How it works

In a cosmetic product, this ingredient slowly decomposes to release trace amounts of formaldehyde. This formaldehyde prevents the growth of bacteria, yeast, and mold, extending the product's shelf life. It is often used alongside other preservatives to create a broad-spectrum antimicrobial system.

Pros

Effective preservation

Helps keep your products free from harmful bacteria and mold, ensuring safety over months of use.

Low irritation potential

At typical use levels, it is considered very low risk for skin irritation, making it suitable for most skin types.

Cons and cautions

Formaldehyde release

It works by releasing small amounts of formaldehyde, which can be a concern for people with allergies or those avoiding formaldehyde entirely.

Synthetic origin

As a man-made chemical, it may not be preferred by consumers looking for naturally derived or preservative-free formulations.

Best for

  • People who use water-based creams or lotions and want a well-preserved product with a long shelf life
  • Those with normal skin who do not have a known formaldehyde allergy

Use caution if

  • Individuals with a known allergy or sensitivity to formaldehyde or formaldehyde-releasing preservatives

Usage tips

Check the full ingredient list for other formaldehyde-releasing preservatives if you have sensitive skin or allergies.
Store products containing this ingredient in a cool, dry place to maintain stability and effectiveness.

Safety summary

Considered safe for use in cosmetics at regulated concentrations. The main concern is potential allergic reactions in individuals sensitive to formaldehyde. Regulatory bodies worldwide have set strict limits to ensure consumer safety.

Research notes

Studies confirm its efficacy as a preservative booster. Safety assessments by the Cosmetic Ingredient Review (CIR) and the SCCS (EU) have concluded it is safe when used within concentration limits. Formaldehyde release is well-documented and controlled.

Common label clues

Typical concentration
0.1% to 1.0%
Regulatory status
Approved for use in cosmetics in the EU, USA, and many other regions. The EU Cosmetics Regulation limits the concentration to 0.5% and requires a warning label if total formaldehyde exceeds 0.05%.
Common uses
Leave-on creams, Lotions, Serums, Shampoos, Conditioners
Environmental note
As a synthetic compound, its environmental fate is not fully studied, but it is used in very small amounts in rinse-off and leave-on products.

Good to know

  • This ingredient is often listed near the end of an ingredient list because it is used at low concentrations.
  • It is not the same as free formaldehyde; the release is gradual and controlled.

Common questions

What is Tris(Hydroxypropyl) Hexahydrotriazine in beauty products?

This ingredient is a man-made preservative booster. It works by slowly releasing tiny amounts of formaldehyde over time to stop bacteria and mold from growing in your skincare products. The amount released is very small and considered safe at the levels used in cosmetics. It's often added to help other preservatives work better, so less of each is needed overall.

What does Tris(Hydroxypropyl) Hexahydrotriazine do in a beauty product?

In a cosmetic product, this ingredient slowly decomposes to release trace amounts of formaldehyde. This formaldehyde prevents the growth of bacteria, yeast, and mold, extending the product's shelf life. It is often used alongside other preservatives to create a broad-spectrum antimicrobial system.

Is Tris(Hydroxypropyl) Hexahydrotriazine safe for most people?

Considered safe for use in cosmetics at regulated concentrations. The main concern is potential allergic reactions in individuals sensitive to formaldehyde. Regulatory bodies worldwide have set strict limits to ensure consumer safety.

Who should be careful with Tris(Hydroxypropyl) Hexahydrotriazine?

Individuals with a known allergy or sensitivity to formaldehyde or formaldehyde-releasing preservatives

Research sources

Cosmetic Ingredient Review (CIR) Safety AssessmentOpenSCCS Opinion on Formaldehyde and Formaldehyde-Releasing SubstancesOpenPubMed - Formaldehyde-releasing preservatives in cosmeticsOpen

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.