Parfum.

What it does

Its only purpose is to add or mask scent; it provides no skin benefit.

Benefits

• Adds a pleasant scent or masks the raw smell of other ingredients (cosmetic/sensory only, not a skin benefit)

Side effects

• The number-one cause of allergic contact dermatitis from cosmetics; this applies to both synthetic and natural/essential-oil fragrance
• About 1.7-4.1% of the general population reacts to a mix of common fragrance ingredients on patch testing (dermatologists screen with standardized fragrance allergen mixes)
• The undisclosed, variable composition makes it hard to pinpoint or avoid the specific allergen
• Can also trigger irritation, and in sensitive people reactions ranging from dermatitis to headaches

Who it's for

People who simply want a scented product and tolerate fragrance well

Who should be careful

Fragrance-sensitive, allergy-prone, eczema-prone, or compromised/sensitive skin should choose fragrance-free instead

• Fragrance allergy - Wikipedia