The 2026 data-driven guide to formaldehyde-releasing preservatives in Australian shower gels and body washes — eczema avoidance shortlist

The short version

Five preservatives — DMDM hydantoin, diazolidinyl urea, imidazolidinyl urea, quaternium-15, and 2-bromo-2-nitropropane-1,3-diol (bronopol) — slowly release formaldehyde inside your shower gel, hand soap and body wash to prevent microbial growth. They’re cheap, effective, and they’re also among the most frequently identified contact allergens by the American Contact Dermatitis Society. Quaternium-15 alone was ACDS’s Allergen of the Year in 2005. They show up in Australian-shelf products from Palmolive, Dove, Pears, Cetaphil’s entry-line ranges, supermarket private label, and almost every gym-grade body wash priced under $10.

This guide names the five formaldehyde-releasing preservatives, explains why dermatologists flag them as the leading avoidable trigger for eczema flares, and shows you how to identify them on labels. For brand-by-brand scanning of Australian shower gels and body washes, the Low Tox Gear Scanner flags all five — and 230+ other rules — on any AU barcode you scan.

Why formaldehyde releasers are different from formaldehyde itself

Pure formaldehyde is rarely used directly in modern personal care — its smell, instability, and regulatory profile make it impractical. Formaldehyde releasers are stable molecules engineered to slowly release small amounts of free formaldehyde inside the product over its shelf life, at concentrations high enough to kill bacteria but theoretically below the threshold that causes immediate skin reaction.

The problem: “below threshold for immediate reaction” does not mean “below threshold for chronic sensitisation.” Repeated daily exposure to free formaldehyde — even at 200-500ppm, the typical level in well-preserved products — sensitises a meaningful share of the population. Once sensitised, that person reacts to all formaldehyde-releasing preservatives, plus pure formaldehyde, plus several formaldehyde-containing professional products (keratin smoothing treatments, certain nail polishes, embalming agents).

The five releasers — what they’re called on labels

  • DMDM hydantoin — the most common in mass-market shampoo, conditioner, body wash and lotion. INCI: DMDM Hydantoin (no synonyms).
  • Diazolidinyl urea — common in moisturisers, foundations, hand soap. INCI: Diazolidinyl Urea.
  • Imidazolidinyl urea — also common in cosmetics and personal care. INCI: Imidazolidinyl Urea.
  • Quaternium-15 — the strongest of the five and ACDS Allergen of the Year 2005. Sometimes listed as Dowicil 200. INCI: Quaternium-15.
  • Bronopol — 2-bromo-2-nitropropane-1,3-diol. The least common of the five but still appears in some baby products and supermarket basics. INCI: Bronopol.

If you see any of these in an ingredient list — anywhere, not just near the bottom — the product is releasing formaldehyde into the formula.

What the dermatology evidence says

Patch-test data from the North American Contact Dermatitis Group’s 2019-2020 cycle (Atwater et al., Dermatitis, 2021) showed:

  • Quaternium-15: 7.4% of 4,272 consecutive patch-tested patients reacted positively. That’s a sensitisation rate roughly four times the EU SCCS’s “allergen of concern” threshold.
  • Formaldehyde itself: 7.8% positive rate, with strong cross-reactivity to the releasers.
  • DMDM hydantoin: 5.1% positive rate.
  • Diazolidinyl urea: 3.4%.
  • Imidazolidinyl urea: 2.6%.

The European Society of Contact Dermatitis ranks formaldehyde and its releasers in the top-10 contact allergens worldwide, consistent across two decades of patch-test surveillance.

Regulatory landscape — where they’re banned vs allowed

  • EU: Formaldehyde itself is banned in cosmetics as of 2019 (EU Regulation 2019/831). Formaldehyde-releasing preservatives are still permitted, but products containing them must carry the warning “contains formaldehyde” on the label if the released free-formaldehyde concentration exceeds 0.05%. Quaternium-15 is also separately regulated and capped at low concentration.
  • Japan: Quaternium-15 is banned outright in cosmetics. The others are restricted.
  • Australia: Permitted under standard cosmetic ingredient rules. The Industrial Chemicals Act 2019 (administered by AICIS) does not restrict any of the five at typical use levels. The TGA permits them in registered listed-medicine topicals.

The result: Australian consumers regularly encounter products that, if sold in Tokyo or carrying the same formulation in Berlin, would either be banned or warning-labelled.

Where they actually appear on Australian shelves

Generalising across the AU shower-gel and body-wash segment from publicly disclosed ingredient lists:

  • Most Palmolive and Palmolive Naturals body wash variants — DMDM hydantoin in older formulations; some newer SKUs have switched to phenoxyethanol.
  • Cetaphil entry-line cleansers — methylparaben + propylparaben + DMDM hydantoin in standard formulations. The “Sensitive” range is reformulated and largely free of these.
  • Many supermarket private-label body washes (Woolworths Essentials, Coles Smart Buy) — frequently use DMDM hydantoin or diazolidinyl urea as the primary preservative.
  • Dove body wash (some legacy SKUs) — DMDM hydantoin appears in some variants, replaced in others.
  • Older Pears Pure & Gentle body wash — historically used quaternium-15; current formulations vary by batch.

Brand formulations change. Always read the actual label on the bottle in front of you — the inventory of which brands use what shifts every product reformulation cycle. The Low Tox Gear Scanner reflects the current label as published by the manufacturer for each barcode in our 21,000+ AU product catalogue.

How to identify them at the shelf in 10 seconds

  1. Read the ingredient list right-to-left. Preservatives appear near the end. If you see any of the five names above, the product is a formaldehyde releaser.
  2. Look for safer preservatives instead. Modern reformulations use phenoxyethanol (mild contact allergen but vastly lower rate than formaldehyde releasers), sodium benzoate + potassium sorbate (food-grade), benzyl alcohol (a fragrance allergen but in lower-risk context), or caprylyl glycol.
  3. Check the “sensitive skin” range. Most brands now offer a reformulated sensitive-skin variant that has dropped the formaldehyde releasers. Cetaphil Restoraderm, Dove Sensitive, Palmolive Naturals Almond & Milk (newer) commonly are free.

How the Low Tox Gear Scanner flags formaldehyde releasers

Our rule database covers all five releasers under the formaldehyde_releaser concern tag. Default severity is red (avoid) — these are among the few rules where we default to red because the dermatology evidence is robust and the safer alternatives are abundant.

Conditions that escalate further: eczema, contact dermatitis, MCAS, fragrance sensitivity, asthma, psoriasis, fibromyalgia, POTS. For users who selected any of these, the scanner pulls every flagged product into the top of the result list and explains the cross-reactivity with other formaldehyde-releasing preservatives.

For a curated shortlist, the eczema-safe personal care guide screens out all five releasers (plus MI, parabens, SLS) across Beauty, Personal Care and Hygiene categories — 199 AU products pass the strict-clean filter as of this month.

Best practice — what we recommend

  • If you have eczema, contact dermatitis, or chronic skin sensitivity, eliminate all five from your daily-contact products (shampoo, body wash, hand soap, moisturiser) first. These are the highest-yield switches.
  • If you’re asymptomatic but want to reduce overall exposure, prioritise leave-on products (moisturisers, lotions) over rinse-off products (shampoo, body wash). Leave-on contact time is much longer.
  • Don’t over-correct to preservative-free. Products without any preservative grow bacteria and become a different risk. Choose products with phenoxyethanol, benzyl alcohol + dehydroacetic acid, or other newer-generation preservatives.

Related guides on Low Tox Gear

Sources

  1. Atwater AR, Petty AJ, Liu B, et al. Contact dermatitis associated with preservatives: retrospective analysis of North American Contact Dermatitis Group data, 1994 through 2016. Dermatitis 2021;32(3):155-159.
  2. Marks JG Jr, Belsito DV, DeLeo VA, et al. North American Contact Dermatitis Group patch-test results. American Journal of Contact Dermatitis, annual reports.
  3. Latorre N, Borrego L, Fernández-Redondo V, et al. Patch testing with formaldehyde and formaldehyde-releasers. Contact Dermatitis 2011;65(5):286-291.
  4. European Commission. Regulation (EU) 2019/831 amending Annex II to Regulation (EC) No 1223/2009 — restriction of formaldehyde in cosmetic products.
  5. European Society of Contact Dermatitis. ESCD Position Paper on Cosmetic Allergens.
  6. SCCS (Scientific Committee on Consumer Safety). Opinion on the safety of imidazolidinyl urea — SCCS/1644/22.
  7. Quaternium-15 ACDS Allergen of the Year 2005 designation.

This guide is educational and does not constitute medical advice. If you have a known contact allergy, consult a dermatologist for individualised patch-test guidance. Last reviewed: May 2026.