Function of Beauty: the customisation quiz is the product, not the shampoo

Function of Beauty built an empire on a quiz. You answer twenty questions about your hair, pick three "goals" (volume, shine, anti-frizz, length), choose a colour, choose a fragrance, name your bottle, and the brand sends you a "custom-formulated" shampoo with your name printed on the front. The bottle arrives in twelve days. It feels personal. It feels like you bought something made for you.

You didn''t. You bought one of approximately a dozen pre-formulated base shampoos with a different fragrance and dye dialled in at the filling line. That''s not us being cynical. That''s how mass cosmetic manufacturing works. The customisation is real in the sense that your bottle does differ slightly from your friend''s. It''s theatre in the sense that the underlying formula is largely the same as every other Function bottle of its base type.

That would be fine — most shampoos are pretty similar under the hood — if the base formulas weren''t doing the work badly. So let''s talk about what''s actually in the bottle.

The receipts. A typical Function of Beauty shampoo lists, in roughly this order: water, sodium lauroyl methyl isethionate (a gentle surfactant, good), cocamidopropyl betaine (fine), a glycol, then a long stretch of silicones, polymers, and synthetic fragrance compounds. The "fragrance" line is where it gets interesting. Function offers around a dozen scent options. Each scent is a proprietary blend the brand isn''t required to disclose. "Fragrance" on a cosmetic label can legally hide dozens of individual compounds, including known allergens and endocrine disruptors. It''s the dirtiest word on most personal care labels and it''s the second most prominent feature of the entire Function product.

The other thing nobody mentions. Function of Beauty shampoos contain polyquaternium-type polymers and silicones that build up on the hair shaft over time. This is also true of most drugstore shampoos. What''s different is the marketing. Function tells you the formula is "made for your hair," so when your hair starts feeling heavier, flatter, or duller around month three, you assume you answered the quiz wrong. You go back, redo the quiz, change your goals. The brand has perfectly engineered a feedback loop where the product''s normal performance degradation becomes a reason to re-subscribe, not a reason to leave.

Why we''re flagging it. Three reasons. First, the fragrance load is high and undisclosed — anyone with a sensitive scalp, eczema, or contact dermatitis history should treat the bottle the way they''d treat any heavily fragranced product, which is cautiously. Second, the customisation language is misleading. You are not getting a bespoke formulation. You are getting a fragrance-and-dye SKU on top of a stock base. Third, the price-per-ml is roughly double a comparable salon shampoo with a cleaner ingredient deck and no theatre.

This isn''t a moral failing on the buyer''s part. The quiz is genuinely fun. Naming your shampoo bottle is genuinely satisfying. The brand understood, before most haircare companies did, that the experience of buying the product is the product. The actual shampoo is the by-product. That''s why their unit economics work and why their retention is so high. It''s also why we''re telling you to skip it.

The deeper pattern. Personalisation marketing has eaten the wellness category in the last five years. Custom vitamin packs, custom skincare routines, custom protein powders, custom shampoo. In every case, the "customisation" is fragrance, dye, packaging, and a quiz. The underlying product is the same stock formula the company has always made. You''re paying a 50–200% premium for the perception of being seen. The brands that do this best are not the ones with the best science. They''re the ones with the best onboarding.

The clean swap. For most adult hair: a solid, fragrance-free shampoo bar with a short ingredient list (sodium cocoyl isethionate or similar gentle surfactant, plant oils, and that''s it). It lasts three to four months, generates no plastic waste, and lets you actually see what you''re putting on your scalp. For thinning or shedding hair, a once-or-twice-weekly scalp serum with rosemary oil or caffeine has more evidence behind it than any "volume" shampoo ever made. Both swaps cost less per month than a Function subscription.

The verdict. Skip. Not because the product is dangerous — it isn''t — but because you''re paying for branding theatre on top of a stock formula. If you love the customisation experience itself, that''s a real thing and worth understanding about yourself. But the haircare isn''t doing what the marketing says it''s doing, and a £14 shampoo bar will outperform it on any honest metric you care to apply.

For why personalisation marketing is so emotionally effective, see our Kokorology piece on the neuroscience of being seen. It''s the same lever. Function just pulled it earlier than the rest.