Formaldehyde is rarely listed as an ingredient. What you'll find instead are compounds that release formaldehyde slowly over time as they break down — and several of these are sitting in common shampoos, conditioners, and body washes on Canadian shelves.
Formaldehyde-releasing preservatives (FRPs) are effective broad-spectrum antimicrobials. They work by slowly releasing small amounts of formaldehyde in the product, which kills bacteria, mould, and yeast that would otherwise contaminate it. Before the risks were better understood, they were widely used — and many still appear in products sold today.
The problem is that formaldehyde is a recognized allergen and sensitizer. Health Canada classifies it as a designated allergen in cosmetics, with concentration limits of ≤0.2% in oral hygiene products and ≤0.1% in other formulations. But the formaldehyde released by FRPs adds up over a product's shelf life — and the total exposure isn't always visible from the label.
| INCI Name | Also Known As | Commonly Found In |
|---|---|---|
| DMDM Hydantoin | Dimethylol dimethyl hydantoin | Shampoos, conditioners, body wash, hair treatments |
| Imidazolidinyl Urea | Germall 115 | Lotions, creams, shampoos, foundations |
| Diazolidinyl Urea | Germall II | Lotions, conditioners, baby products |
| Quaternium-15 | Dowicil 200 | Shampoos, liquid soaps, sunscreens |
| Bronopol | 2-Bromo-2-Nitropropane-1,3-Diol | Baby wipes, cleansers, baby shampoos |
All five are restricted under the Health Canada Cosmetic Ingredient Hotlist. Quaternium-15 is among the most common causes of cosmetic contact dermatitis in North America. DMDM Hydantoin has been the subject of multiple class-action lawsuits in the United States over hair loss claims.
Being "restricted" means Health Canada has placed concentration limits and product-type conditions on their use — not that they're banned. Within those limits, a manufacturer can legally include them. Many do, particularly in rinse-off products like shampoos where exposure time is shorter.
They're also inexpensive and effective, which makes reformulation a cost decision for brands. The wave of "free from" marketing that drove paraben reformulations has not been as loud about FRPs — meaning many consumers don't know to look for them.
People with existing skin sensitivities, contact dermatitis, or eczema are at higher risk of reacting to FRPs. Reactions typically manifest as redness, itching, or a rash at the site of product application. Because shampoo and conditioner rinse down the face, neck, and back, reactions can appear in those areas even if you're not applying the product directly to skin.
Repeated exposure can also induce sensitization in people who weren't previously reactive — meaning a product you've used for years without issue can suddenly cause problems.
Scan the ingredient list for any of the five names above. They're often found in the second half of the list (under 1% concentration) alongside other preservatives. If you see "urea" in an ingredient name, that's worth a closer look — imidazolidinyl urea and diazolidinyl urea are both FRPs, while regular urea (a humectant) is not.
Bronopol is sometimes listed by its chemical name "2-Bromo-2-Nitropropane-1,3-Diol" — both names are permitted under INCI.
Tip: DMDM Hydantoin is one of the most commonly found FRPs in drugstore shampoos. If you're experiencing scalp irritation or hair shedding and have been using the same shampoo for a while, it's worth checking the label.
SkinCompass flags formaldehyde releasers and every other restricted ingredient instantly — just scan the barcode.