Fragrance-Free, Not Just "Unscented": Formulating for Sensitive Skin
Ask people why they started making their own skincare, and "my skin reacts to everything" comes up again and again. The good news: gentle formulating is a learnable skill. It starts with the single most common culprit.
Fragrance: the usual suspect
DermNet notes that fragrance allergy is second only to nickel as a cause of allergic contact dermatitis, and that around 10% of people who get patch tested react to fragrance (DermNet). A 2021 review agrees that fragrances and preservatives are the most frequent cosmetic ingredients behind contact dermatitis (Pastor-Nieto & Gatica-Ortega, 2021).
That includes "natural" fragrance. Essential oils contain the same allergens as many synthetic perfumes (see our essential oil safety post).
"Unscented" is not "fragrance-free"
This trips up shoppers and brands alike:
- Fragrance-free means no fragrance ingredients at all, even ones you can't smell.
- Unscented products may contain a masking fragrance to cover the smell of the base ingredients.
The American Academy of Dermatology explains the difference clearly (AAD), and the FDA notes that even some "unscented" products may contain fragrance ingredients (FDA). For sensitive skin, "fragrance-free" is the one to aim for.
Hidden fragrance sources to watch
- Essential oils and absolutes.
- Strongly aromatic botanical extracts and hydrosols. They're lovely, but they carry natural fragrance compounds.
- "Parfum", "aroma" or "flavour" in a supplier's composition. Always check the full composition sheet.
The minimalist formula approach
Fewer ingredients means fewer chances to react, and it's much easier to pin down a culprit if something does go wrong. Formulators often describe reducing both the number and the concentration of ingredients as a "minimalist" strategy for sensitive skin (a point made in an industry-authored study: Messaraa et al., Cosmetics, 2022).
A gentle moisturiser blueprint (around 10 ingredients):
- Water + Glycerin
- A mild emulsifier, such as Cetearyl Olivate and Sorbitan Olivate
- Simple, low-odour emollients: Squalane, Caprylic/Capric Triglyceride
- Barrier support: Ceramide Complex (see Ceramides 101)
- One or two soothers: Colloidal Oatmeal, Allantoin, Panthenol, Bisabolol, Ectoin or Madecassoside
- A well-tolerated preservative at its lowest effective level, confirmed by challenge testing
- pH around 5
Leave out the essential oils, the botanical "cocktail" and the strong actives. Sensitive-skin products are not the place for 10% acids.
"But the base smells a bit odd"
Some raw materials have a faint natural odour (waxy, fatty, slightly sweet). That's normal and honest. Choose refined, low-odour grades where possible, and tell customers that a faint natural scent is expected.
Testing your product
The AAD suggests a simple home test for anyone trying a new product: apply a small amount to the inner arm or bend of the elbow twice a day for 7–10 days, and stop if a reaction appears (AAD). Brands can go further with dermatologist-supervised patch testing or repeat-insult patch testing (HRIPT) before making "suitable for sensitive skin" claims.
Explore Sensitive Skin, Soothing & Anti-Irritant Agents and Baby & Sensitive Care Ingredients.
If you suspect an allergy, a dermatologist can patch test to identify the exact trigger.