At a glance
| Chemical family | Formaldehyde-releasing cosmetic preservative; quaternary ammonium chloroallyl-substituted hexamine; in-product hydrolysis releases formaldehyde for antimicrobial effect. Other releasers in same class: DMDM hydantoin, imidazolidinyl urea, diazolidinyl urea, sodium hydroxymethylglycinate, bronopol |
| CAS number | 51229-78-8; also marketed as Dowicil 200; chemical name 1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride |
| Classification | Quaternium-15 itself: not formally evaluated by IARC. Released formaldehyde: IARC Group 1 (carcinogenic to humans, Monograph Vol 100F, 2012). EU Cosmetics Regulation 1223/2009 Annex V permits quaternium-15 at up to 0.2% in finished products with "contains formaldehyde" labeling required above 0.05% free formaldehyde. American Contact Dermatitis Society Allergen of the Year 2005. CIR Safety Assessment supports current use levels |
| Where you encounter it | Shampoos, conditioners, lotions, sunscreens, liquid hand soaps, body washes, mascara, foundation, some baby wipes — historically common, declining post-2005 ACDS designation but still appears in many current product ingredient lists, particularly mass-market and lower-cost lines |
| Sleep micro environment relevance | Same indirect pathway as DMDM hydantoin — leave-on products transfer to bedding overnight with continuing formaldehyde release. Quaternium-15 specifically carries elevated bedroom relevance for sensitized patients because product residue on pillowcases produces ongoing contact-allergen exposure during the sleep window |
| Activated carbon capture | Limited applicability for product-residue dermal exposure; activated carbon can capture released formaldehyde from bathroom air during application. Primary intervention is product-choice level. Inferred from established formaldehyde-releaser exposure pathways |
Regulatory & certification status
Where Quaternium-15 stands across the major regulatory systems and the certifications a bedroom product might carry. Each row links to the governing instrument; where a jurisdiction has no specific measure, that is stated plainly rather than left blank.
| European Union | Prohibited in cosmetics. Commission Regulation (EU) 2019/831 added the cis-isomer of Quaternium-15 (cis-1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride, cis-CTAC; CAS 51229-78-8) to Annex II (prohibited substances) of the Cosmetic Products Regulation (EC) No 1223/2009 as entries 1385/1386, and deleted Quaternium-15 from the Annex V list of allowed preservatives (entry 31). The regulation records that the cis-isomer carries a harmonised CLP classification as a CMR substance of category 2 and that the SCCS found the safety of Quaternium-15 in cosmetics could not be established; the measure entered into force in June 2019. No REACH SVHC Candidate List, Authorisation List (Annex XIV) or restriction (Annex XVII) entry for Quaternium-15 was identified — the EU control runs through the Cosmetics Regulation. Regulatory — UK legislation · EUR-Lex |
| United States | No federal restriction identified. Quaternium-15 is listed on the TSCA Chemical Substance Inventory as an existing chemical, but no TSCA risk evaluation or risk-management action restricting it was identified. Under California Proposition 65, Quaternium-15 is not listed: it does not appear on the OEHHA Proposition 65 list by name or by CAS 51229-78-8 / 4080-31-3 (verified against the OEHHA list file). Only its breakdown product, formaldehyde (gas) (CAS 50-00-0), is a Prop 65 listed carcinogen — a separate substance. Regulatory — OEHHA |
| Canada | Not currently restricted in Canada; proposed action is still at the draft stage. In the DRAFT Hexamethylenetetramines Group screening assessment (notice in Canada Gazette Part I, 6 March 2021), cis/trans-CTAC and cis-CTAC (INCI Quaternium-15) are PROPOSED to meet the CEPA paragraph 64(c) human-health criterion — concern over dermal exposure of infants, toddlers and children from products such as body moisturizers and sunscreen lotions — but not the environmental criteria. This is a proposed (not final) conclusion: no final screening assessment was identified, and the substances are NOT on Schedule 1 (Toxic Substances List); Canada has only proposed to add them. Health Canada's own Quaternium-15 page states it 'is not currently restricted in Canada.' Separately, Health Canada's Cosmetic Ingredient Hotlist restricts formaldehyde and formaldehyde-releasing cosmetics by concentration and labelling (e.g. lower limits for products that release formaldehyde vapour in use), but the Hotlist does not name Quaternium-15 as a restricted entry. Regulatory — Canada Gazette · Government of Canada |
| Australia | AICIS assessed Quaternium-15 / cis-Quaternium-15 (CTAC) within its evaluation of 'Hexamine and related chemicals' (EVA00154), published as a final Evaluation Statement on 26 June 2024 (preceded by a 15 April 2024 draft and listed in the AICIS notice of completed evaluations of 28 June 2024). The evaluation characterises the substances' hydrolysis in water to formaldehyde and their human-health and environmental profile; the precise recommended controls / risk conclusions were not confirmable verbatim from the primary statement text, so no specific restriction is asserted here. Regulatory — AICIS |
| United Kingdom | Great Britain inherited the EU position at the end of the transition period: Quaternium-15 (cis-CTAC) is prohibited in cosmetics under the GB-retained Cosmetic Products Regulation (Annex II), which carried over the prohibition introduced by EU 2019/831, and the cis-isomer's harmonised CMR category-2 classification carries into GB CLP (administered by HSE). No additional GB-specific restriction beyond the retained framework was identified; the precise current GB Annex II/CLP entry was not independently re-verified against an HSE/OPSS primary list here. Regulatory — UK legislation · HSE |
| Certifications | CertiPUR-US: not addressed — the program targets polyurethane foam content and emissions, and Quaternium-15 is a wet-applied cosmetic/textile preservative, not a foam constituent it screens for. OEKO-TEX Standard 100: per Hohenstein's published FAQ, it tests for formaldehyde and forbids most biocidal/biologically active substances in certified textiles, so it would constrain formaldehyde released by such a preservative; however Quaternium-15 is not confirmed as a named entry on its restricted-substance list, and the FAQ does not publish per-product-class formaldehyde limits (those live in the separate standard documents). GREENGUARD / GREENGUARD Gold: a low-VOC chamber-emissions certification that does not screen for a non-volatile preservative salt like this. Industry — OEKO-TEX Standard 100 · CertiPUR-US |
| The 72-hour test window | Largely missed as the parent compound. Quaternium-15 is a non-volatile quaternary-ammonium solid that does not off-gas, so a short ~72h chamber test would not capture the molecule itself; what such a test could detect is the formaldehyde it slowly releases, which is volatile — but that registers as formaldehyde, not as Quaternium-15. Inferred — from the compound's volatility/emission profile versus the VOC focus of short chamber tests |
What it is
Quaternium-15 — CAS 51229-78-8, chemical name 1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride, marketed historically as Dowicil 200 — is a synthetic formaldehyde-releasing cosmetic preservative in commercial use since the 1960s. The parent compound is a quaternary ammonium salt with a chloroallyl substituent on a hexamethylenetetramine (methenamine) backbone. Under the aqueous conditions of a cosmetic formulation, the parent compound decomposes slowly to release formaldehyde, which provides the broad-spectrum antimicrobial preservation effect against bacteria, yeasts, and fungi.
Quaternium-15 releases formaldehyde at one of the highest rates among cosmetic formaldehyde-releasers — typically generating somewhat more free formaldehyde per unit preservative mass than DMDM hydantoin, imidazolidinyl urea, or diazolidinyl urea under comparable conditions. The higher release rate produces effective antimicrobial activity at the lower regulatory concentration limit (0.2% maximum in EU Cosmetics Regulation vs DMDM hydantoin's 0.6% limit), but also produces correspondingly higher contact-allergen activity for sensitized patients. The 0.2% EU limit reflects this dose-response.
The released formaldehyde is the chemical of toxicological concern — IARC Group 1 carcinogen — but the parent compound has additional clinical relevance for contact dermatitis. Patients with documented quaternium-15 contact allergy can react to the parent compound at sub-regulatory free-formaldehyde levels, and cross-reactivity with formaldehyde itself and with other formaldehyde-releasers is common but not universal. The contact-allergen specificity is one reason quaternium-15 received the 2005 ACDS Allergen of the Year designation while the released-formaldehyde exposure also drives the broader Group 1 carcinogen regulatory framework.
Where you encounter it
From shampoos, conditioners, and hair products
Historically the largest single use category by product volume. Mass-market shampoos and conditioners regularly used quaternium-15 as a preservative through the 1990s and 2000s; use has declined since the 2005 ACDS designation pushed reformulation activity across the industry, but quaternium-15 still appears in many current US-market shampoo and conditioner ingredient lists.
From lotions, sunscreens, and leave-on skin products
Leave-on body lotions, hand creams, sunscreens, and similar skin products use quaternium-15 in some formulations. The all-over body application produces measurable cumulative dermal exposure to both the parent compound and the released formaldehyde. de Groot, White, Flyvholm, Lensen and Coenraads 2010 in Contact Dermatitis documented the prevalence of formaldehyde-releasers including quaternium-15 across cosmetic product categories in the EU and US markets. Peer-reviewed
From hand soaps and body washes
Liquid hand soaps, body washes, and similar rinse-off cleansing products commonly contain quaternium-15. The rinse-off nature reduces per-application exposure, but the frequency of hand-soap use makes the cumulative dose meaningful — and for quaternium-15-sensitized patients, even brief contact can trigger dermatitis.
From makeup and cosmetic products
Mascara, foundation, concealer, and similar cosmetic products use quaternium-15 in some formulations. The application areas include sensitive skin regions (periocular for mascara, face for foundation) with relatively high permeability. For quaternium-15-sensitized patients, cosmetic-product ingredient labels deserve specific scrutiny.
From baby wipes and pediatric products
Some baby wipes and baby-care products have historically contained quaternium-15. The infant exposure context — frequent application, high skin permeability, large surface area relative to body mass — gave the quaternium-15-in-baby-products concern particular consumer salience during the 2000s consumer-pressure cycle.
What the research says
Allergic contact dermatitis — the dominant clinical endpoint
The dominant documented health endpoint for quaternium-15 is allergic contact dermatitis, and quaternium-15 is one of the most clinically prominent cosmetic-preservative allergens. de Groot, Flyvholm, Lensen, Menné and Coenraads 2009 in Contact Dermatitis reviewed the relationship between formaldehyde-releasers and formaldehyde contact allergy, with quaternium-15 documented as one of the most frequent positive patch-test allergens in the class. Peer-reviewed The clinical pattern: patients sensitized to quaternium-15 typically also react to formaldehyde itself on patch testing, and the cross-reactive set extends across the broader formaldehyde-releaser family.
2005 ACDS Allergen of the Year
The American Contact Dermatitis Society named quaternium-15 the Allergen of the Year for 2005 — the annual designation that surfaces a chemical with substantial clinical-allergy prevalence and broad exposure relevance. Peer-reviewed — published in Dermatitis The 2005 designation reflected the North American Contact Dermatitis Group patch test surveys showing quaternium-15 in the top five of cosmetic-preservative positive reactions, with sensitization rates around 9-10% of patch-tested patients during the early-2000s period. The designation drove substantial industry reformulation activity over the following decade and informed subsequent EU SCCS regulatory attention.
NACDG patch test surveys — the population-level prevalence data
The North American Contact Dermatitis Group has conducted standardized patch test surveys in dermatology clinics across multiple two-year cycles since the 1980s, providing the population-level prevalence data for cosmetic-ingredient sensitization. Quaternium-15 has consistently appeared in the top tier of positive-reaction rates across these surveys, alongside fragrance mixes, nickel, and a small number of other clinically prominent allergens. The patch-test prevalence is the clinical signal that informs the regulatory and industry response.
Released formaldehyde — IARC Group 1 framing
The IARC Monograph Volume 100F (2012) classified formaldehyde as Group 1 — carcinogenic to humans — based on nasopharyngeal cancer and leukemia in occupationally exposed populations. Regulatory The Group 1 classification applies to the released formaldehyde from quaternium-15, not to the parent compound. The exposure dose at typical cosmetic use is substantially below the occupational inhalation exposures that anchor the Group 1 classification; the consumer relevance is the cumulative low-dose exposure across many product uses over years, parallel to the DMDM hydantoin framing.
CIR safety assessment
The Cosmetic Ingredient Review Safety Assessment of Quaternium-15 conducted the structured industry safety review and concluded current use levels are safe for cosmetic preservation given the released-formaldehyde concentration profile. Industry investigation CIR's position is parallel to its assessment of DMDM hydantoin; the EU Cosmetics Regulation's 0.2% limit (lower than DMDM hydantoin's 0.6%) reflects the stronger contact-allergen activity of quaternium-15 specifically.
EU regulatory framework
EU Cosmetics Regulation No. 1223/2009 Annex V permits quaternium-15 at up to 0.2% in finished cosmetic products. Regulatory The "contains formaldehyde" labeling requirement applies when finished-product free formaldehyde exceeds 0.05%, consistent with the broader formaldehyde-releaser labeling framework. The 0.2% concentration limit is the lowest of the major formaldehyde-releaser EU concentration limits, reflecting the higher contact-allergen potency. EU SCCS opinions on quaternium-15 have informed the regulatory framework but quaternium-15 has not been subject to the same level of high-profile EU SCCS review activity as parabens received in 2010-2014.
What helps reduce exposure
In the EU, it's largely already handled. Quaternium-15 is banned in EU cosmetics, so EU-market products shouldn't contain it at all; the live decision is mostly for US and imported products, where it still appears.
If you're formaldehyde-sensitive, treat quaternium-15 as a prime suspect. It is the most frequent releaser allergen on patch testing, so for anyone with a known formaldehyde or quaternium-15 allergy it is the one most worth scanning labels for. Because cross-reactivity is common, a positive result usually argues for avoiding the whole releaser class — ideally with a contact-dermatology specialist's guidance on which specific donors you tolerate.
The rest of the playbook is class-level. Reading the preservative section of ingredient lists, ventilating the room during leave-on product use, choosing releaser-free baby products, and using the EU "contains formaldehyde" label as a shortcut apply to every donor equally — they're laid out on the formaldehyde-releasing preservatives explainer.
What does NOT help
- Buying "formaldehyde-free" products without checking the ingredient list. Formaldehyde-releasing preservatives still produce formaldehyde in-product even when "formaldehyde" itself isn't listed as a separate ingredient. The "free from" claim is technically true while functionally misleading.
- Generic "non-toxic" or "natural" labels. Unregulated marketing terms. Specific ingredient verification or third-party certification (EWG Verified, MADE SAFE) is the actionable level.
- Assuming "preservative-free" claims mean releaser-free. Some products labeled "preservative-free" use alternative preservation systems that may not be conventional preservatives but still affect microbial growth. Read the full ingredient list rather than relying on category-level claims.
- Switching from quaternium-15 to a different formaldehyde-releaser to avoid the allergen. For quaternium-15-sensitized patients, the entire class typically needs avoidance. Switching to DMDM hydantoin or imidazolidinyl urea does not address the underlying released-formaldehyde concern or the cross-reactivity pattern.
Open research questions
- Differential sensitization rates across formaldehyde-releasing preservatives — quaternium-15 appears among the highest in patch-test data, but the relative ranking shifts with measurement methodology and across regional patch-test panels. Speculation — the ranking is established at population level; the methodology-dependent variation is the active research area
- Cumulative formaldehyde-releaser exposure across leave-on and rinse-off products — the integrated daily formaldehyde dose from personal care across multiple product categories has not been quantitatively studied at population scale. Speculation
- Pediatric sensitization patterns — quaternium-15 contact allergy in children and infants is less precisely characterized than the adult literature. Inferred from established adult-versus-pediatric differences in cosmetic-ingredient contact dermatitis
- Replacement preservative safety profiles — as quaternium-15 phase-out has progressed, the cumulative population exposure to alternative preservation chemistries (parabens, phenoxyethanol, isothiazolinones, organic acids) has shifted without parallel exposure-assessment work. Speculation
Citations
- Cosmetic Ingredient Review. Safety Assessment of Quaternium-15 as Used in Cosmetics. cir-safety.org Industry investigation — formal industry safety review
- Cahill J, Nixon R (2005). Allergic contact dermatitis to quaternium 15 in a moisturising lotion. Australasian Journal of Dermatology, 46(4):284-285. DOI 10.1111/j.1440-0960.2005.00207.x Peer-reviewed — example of the 2005 Allergen of the Year clinical literature
- de Groot AC, Flyvholm M-A, Lensen G, Menné T, Coenraads P-J (2009). Formaldehyde-releasers: relationship to formaldehyde contact allergy. Contact Dermatitis, 61(2):63-85. DOI 10.1111/j.1600-0536.2009.01582.x Peer-reviewed — foundational releasers/formaldehyde allergy review
- de Groot AC, White IR, Flyvholm M-A, Lensen G, Coenraads P-J (2010). Formaldehyde-releasers in cosmetics: relationship to formaldehyde contact allergy. Contact Dermatitis, 62(1):2-17. DOI 10.1111/j.1600-0536.2009.01615.x Peer-reviewed
- de Groot AC, Veenstra M (2010). Formaldehyde-releasers in cosmetics in the USA and in Europe. Contact Dermatitis, 62(4):221-224. DOI 10.1111/j.1600-0536.2009.01623.x Peer-reviewed
- International Agency for Research on Cancer (2012). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 100F: Chemical Agents and Related Occupations — Formaldehyde Group 1 (carcinogenic to humans). Lyon: IARC. publications.iarc.who.int Regulatory — applies to released formaldehyde
- European Commission. Cosmetics Regulation (EC) No. 1223/2009 — Annex V (list of preservatives), Quaternium-15 entry permitted at 0.2% in finished products; Article 19 labeling requirements including "contains formaldehyde" disclosure above 0.05% free formaldehyde. health.ec.europa.eu/cosmetic-products Regulatory
- Warshaw EM, Belsito DV, DeKoven JG, Maibach HI, Taylor JS, Zug KA, Sasseville D, Fransway AF, Mathias CGT, Pratt MD, Marks JG (2015). North American Contact Dermatitis Group patch test results: 2011-2012. Dermatitis, 26(1):49-59. DOI 10.1097/DER.0000000000000097 Peer-reviewed — NACDG patch-test prevalence data
- Cosmetic Ingredient Review. Safety Assessment of Formaldehyde and Methylene Glycol as Used in Cosmetics — covers formaldehyde and formaldehyde-releasers collectively. cir-safety.org Industry investigation
- European Chemicals Agency (ECHA). Substance Information for Quaternium-15 — REACH registered substance information. echa.europa.eu Regulatory
Frequently asked questions
Is quaternium-15 dangerous?
The dominant documented health endpoint is allergic contact dermatitis. Quaternium-15 is consistently among the most frequent positive cosmetic-preservative patch test allergens in dermatology clinics — the American Contact Dermatitis Society named it Allergen of the Year for 2005 specifically to highlight this clinical prevalence. Systemic toxicity from cosmetic-use exposure is generally low. The released formaldehyde itself is IARC Group 1 (carcinogenic to humans, Monograph Vol 100F 2012), but the cosmetic-use exposure dose is substantially below the occupational inhalation exposures that anchor the Group 1 classification.
Why was quaternium-15 named Allergen of the Year?
The American Contact Dermatitis Society's annual Allergen of the Year designation highlights a chemical with substantial clinical-allergy prevalence and broad exposure relevance. Quaternium-15 received the 2005 designation because the North American Contact Dermatitis Group patch test surveys consistently ranked it in the top five of cosmetic-preservative positive reactions, with sensitization rates around 9-10% of patch-tested patients during the early-2000s period. The 2005 ACDS designation drove substantial cosmetic-industry reformulation activity over the following decade.
Does quaternium-15 release formaldehyde?
Yes — quaternium-15 is a formaldehyde-releasing preservative. The chemistry of the parent compound (chloroallyl-substituted methenamine/hexamine) decomposes slowly in aqueous cosmetic formulations to release formaldehyde, which is what produces the antimicrobial preservation effect. Quaternium-15 releases formaldehyde at one of the highest rates of the cosmetic formaldehyde-releaser class — comparable to or higher than DMDM hydantoin, imidazolidinyl urea, and diazolidinyl urea. The released formaldehyde, not the parent compound, is the IARC Group 1 chemical of toxicological concern.
Is quaternium-15 in baby products?
Some baby wipes, baby shampoos, and baby lotions historically contained quaternium-15, though use has declined since the 2005 Allergen of the Year designation and subsequent consumer pressure. EU Cosmetics Regulation permits quaternium-15 at up to 0.2% in finished products, with the same "contains formaldehyde" labeling requirement that applies to all formaldehyde-releasing preservatives when released formaldehyde exceeds 0.05% in the finished product. For infants and young children, prioritizing formaldehyde-releaser-free options for leave-on products specifically is reasonable — the per-body-weight cumulative exposure across many baby-care products in a daily routine can be substantial.
What products contain quaternium-15?
Shampoos, conditioners, lotions, sunscreens, liquid hand soaps, body washes, mascara, foundations, some cosmetic products, and some baby wipes have historically contained quaternium-15. Use has declined since the 2005 Allergen of the Year designation and the EU SCCS regulatory attention, but quaternium-15 still appears on many current ingredient labels — particularly in mass-market and lower-cost product lines. The compound may be listed as "quaternium-15," "Dowicil 200," or by the full chemical name on different products.
How do I know if I'm allergic to quaternium-15?
Patch testing by a dermatologist or allergist is the clinical standard for diagnosing contact allergy to specific cosmetic ingredients including quaternium-15. The North American Contact Dermatitis Group standard patch test series includes quaternium-15 and the other major formaldehyde-releasers. Suspect contact dermatitis presents as a chronic or recurring itchy red rash on areas where cosmetic products are applied — face, neck, scalp, hands, underarms. If patch testing confirms quaternium-15 sensitization, the standard clinical recommendation is to avoid the entire formaldehyde-releaser class rather than just quaternium-15, because cross-reactivity within the class is common.
What's the difference between quaternium-15 and DMDM hydantoin?
Both are formaldehyde-releasing cosmetic preservatives, structurally distinct but functionally similar. Quaternium-15 is a quaternary ammonium chloroallyl-substituted hexamine compound; DMDM hydantoin is a hydantoin-derived compound. Quaternium-15 is a stronger and more frequent contact allergen than DMDM hydantoin in patch-test clinic data — the 2005 ACDS Allergen of the Year designation reflected this clinical prominence. Both produce formaldehyde release in cosmetic formulations and both fall under the EU "contains formaldehyde" labeling requirement above 0.05% free formaldehyde in finished product. EU regulation permits quaternium-15 at 0.2% maximum vs DMDM hydantoin at 0.6% maximum — the lower quaternium-15 limit reflects the higher contact-allergen potency.
Related compounds
Embr is a sleep environment company researching the chemistry of the bedroom. See the methodology page for how this Atlas tags claims by evidence strength. For broader context on personal care chemistry and formaldehyde exposure pathways, see non-toxic bedroom and the formaldehyde atlas entry.
Last reviewed 2026-05-25. If you find a factual error, contact us.