Propylene Glycol and Diazolidinyl Urea Based Cream as an Emollient
A propylene glycol (PG) and diazolidinyl urea (DU) based cream is NOT suitable as a first-line emollient, particularly for patients with scalp dandruff and potential skin sensitivities, due to the well-documented risk of contact dermatitis from both ingredients.
Why This Formulation Is Problematic
Propylene Glycol Concerns
PG is a frequent contact allergen in patients with atopic dermatitis and sensitive skin, with fragrances and preservatives (particularly propylene glycol) being common sources of allergic reactions in emollients and topical preparations 1.
Contact sensitization occurs in approximately 0.31% of patch-tested patients, with 42.9% of those reactions being clinically relevant, and topical corticosteroids and moisturizers being the most common exposure sources 2.
PG produces both irritant and allergic reactions, making positive patch test results difficult to interpret, and allergic reactions can be confirmed through clinical relevance, usage testing, or oral provocation 3.
The irritant potential is concentration-dependent, with testing at 5-10% concentrations potentially missing some reactions, suggesting higher concentrations in formulations pose greater risk 2.
Diazolidinyl Urea Concerns
- Diazolidinyl urea is specifically identified as a problematic preservative alongside propylene glycol in the context of contact allergens for patients with atopic dermatitis 1.
What You Should Recommend Instead
First-Line Emollient Selection
High lipid content formulations without sensitizing preservatives are essential for maintaining skin hydration and restoring barrier function 4.
Urea-containing emollients (10-20% urea with glycerol) provide superior barrier strengthening compared to simple paraffin creams, with demonstrated reduction in transepidermal water loss and protection against irritants 4, 5.
Simple emollient alternatives include Diprobase cream or ointment, Epaderm cream, Cetraben, Hydromol cream or ointment, and Doublebase gel 6.
Application Protocol
Apply emollients at least twice daily, with optimal timing immediately after bathing when skin remains slightly damp to maximize hydration retention 4, 6.
Prescribe adequate quantities of at least 400-500g containers to ensure sufficient supply for 2-4 weeks of twice-daily application 6.
For Scalp Dandruff Specifically
Interestingly, propylene glycol at 15% concentration in an ethanol-water solution showed efficacy for seborrheic dermatitis of the scalp (89% healing rate vs 32% control), with significant reduction in Pityrosporum orbiculare organisms 7.
However, this leave-on scalp solution differs fundamentally from an emollient cream formulation, and the scalp's tolerance profile differs from facial and body skin, particularly in patients with existing sensitivities 7.
Critical Clinical Pitfall
The most important caveat is that simple paraffin-based creams may actually reduce natural moisturizing factors in the skin, demonstrating that not all emollients are equivalent 5. A PG/DU-based formulation combines this potential ineffectiveness with active sensitization risk, making it doubly problematic.
When to Suspect PG Allergy
Consider PG allergy in patients with worsening dermatitis despite topical corticosteroid use, as topical corticosteroids are the most common source of PG exposure causing allergic contact dermatitis 2.
Patch testing to PG should be performed in patients with suspected contact dermatitis to topical preparations, using both 5% petrolatum and 10% aqueous concentrations 2.