Function of Beauty Review 2026: What the Hair Quiz Doesn’t Tell You
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The pitch is close to irresistible. Answer a few questions, pick a colour and a scent, and receive a shampoo formulated for your exact hair — 87 trillion possible combinations, your name printed on the bottle. Function of Beauty launched in 2016 out of MIT and turned personalization into one of the most Instagrammed ideas in haircare. Nearly a decade on, the picture is considerably more complicated than the quiz suggests. This Function of Beauty review sets out what our TrendsInReview team found across 27,000+ Trustpilot ratings, independent formulation analyses, and a substantial body of critical customer feedback — including complaints you should read before you order.
What Is Function of Beauty?
Function of Beauty is a New York-based custom haircare brand founded in 2016 by MIT engineers Zahir Dossa, Joshua Maciejewski, and Hien Kaplan. Customers take a hair quiz — natural hair type, structure, scalp moisture, up to five hair goals — then choose fragrance strength, colour, and optional silicone-free, dye-free, or fragrance-free formulations. The brand then manufactures the formula to order in the United States. The range spans shampoo, conditioner, leave-in conditioner, serum, mask, and styling primer, plus body wash and skincare. Products are sulfate-free, paraben-free, phthalate-free, vegan, and cruelty-free. Custom shampoo starts around $25; a shampoo and conditioner set typically runs $39–$54 depending on size.
What Makes Function of Beauty Stand Out
- Genuine formulation choice: five hair goals selected simultaneously, plus silicone-free, dye-free, and fragrance-free toggles — more control than any off-the-shelf brand offers.
- Regulatory and safety posture: the brand states every ingredient meets both US and EU cosmetic regulations, formulations are reviewed by an expert toxicologist, and products are manufactured in the US under clinical testing protocols.
- A large, mostly positive review base: 4.1 stars across more than 27,700 Trustpilot reviews — a sample size that makes the positive signal meaningful.
- Fragrance-free and dye-free options: a real advantage for sensitive scalps, and unusual in a brand built on colourful, heavily scented bottles.
- Retail availability: select formulas now sell through Sephora, which means promotional pricing and straightforward returns.
How the Custom Shampoo Actually Works
Before you spend money, understand the single most consequential thing about the Function of Beauty custom shampoo — and the brand does not make it obvious.
1. Custom Shampoo — from around $25 (11 oz)
Sulfate-free, formulated to your quiz answers. Critical guidance from independent testers: choose scalp-and-root goals for your shampoo, not length goals. Selecting “deep condition” or “fix split ends” loads the shampoo with heavy ingredients that leave roots oily and flat. This single mistake explains a large share of the brand’s negative reviews.
2. Custom Conditioner — from around $25
Here you do the reverse: select length-and-end goals. Testers report the shampoo and conditioner work considerably better as a pair than either does alone — which some reviewers reasonably regard as a design flaw rather than a feature.
3. Custom Hair Mask — around $19
Well-received, though one independent reviewer concluded it was not better than the many non-custom masks available for dry, damaged, or coloured hair — a fair point about the whole customization premise.
4. Custom Hair Serum — around $19
A lightweight leave-in for frizz and shine. One of the less-complained-about products in the line.
5. Bond Repair Custom Shampoo (Sephora)
Available with add-on concentrates such as Frizz Genius and Color Savior. Buy it on Sephora promotion rather than at full price — reviewers who paid full price were markedly less satisfied than those who did not.
What Real Customers Say — Read This Section Carefully
The positive reviews are real and numerous. Function of Beauty holds 4.1 stars from more than 27,700 Trustpilot reviews. Customers describe softer, defrizzed, more voluminous hair, love the quiz experience and the scent options, and cite the personalized bottles as a genuine delight. Independent testers who selected their goals correctly report balanced oil production, longer-lasting colour, and hair that stays clean at the roots between washes. Several long-term customers of six years or more remain loyal.
The critical picture is where a responsible Function of Beauty review has to slow down. Independent review aggregators describe the brand as polarized rather than reliably good, citing formulas that perform like standard shampoos, overpowering fragrances, residue and buildup, weak moisturization for textured hair, and faulty pumps. Shipping delays of three to four weeks are reported even by loyal repeat buyers. More seriously: a 2021 VICE article reported that a number of customers complained the products were causing hair loss, and the brand’s Better Business Bureau page carries an average rating of around 1.17 out of 5. Function of Beauty has responded publicly that it stands behind its products, that every ingredient meets US and EU cosmetic regulations, that formulations are reviewed by a toxicologist, and that manufacturing includes clinical testing — and the company does respond to individual complaints. Separately, one ingredient-analysis site generated a random custom formula and concluded it contained no active ingredients with research backing. We are not in a position to adjudicate causation, and neither is anyone reading a review page: if you experience unusual shedding with any product, stop using it and speak to a dermatologist. Our
hair care guide covers the routine fundamentals worth getting right first.
Social Media & the Personalization Trend
Function of Beauty was among the first brands to understand that a bottle with your name on it is free advertising. Its 2016 Instagram launch created the custom-haircare category and inspired direct competitors including Prose and Formulate. The flip side of that visibility is that dissatisfied customers are equally visible — TikTok hosts a substantial volume of critical before-and-after content, and the brand’s BBB profile is far less flattering than its Trustpilot one. That gap between platforms is itself the most useful thing a prospective buyer can know.
Is Function of Beauty Worth It? Our Verdict
Cautiously, and only if you shop it correctly. The customization is real, the fragrance-free and dye-free options are genuinely useful, and thousands of customers are satisfied. But this Function of Beauty review cannot recommend it unreservedly: the review picture is materially split across platforms, formulation experts question whether the custom formulas contain meaningfully active ingredients, and the volume of critical feedback is higher than for any other brand in this roundup. If you want to try it: choose scalp goals for shampoo and length goals for conditioner, buy on a Sephora promotion, and stop immediately if you notice unusual shedding. Experience: 4/5. Formulation: 2.5/5. Consistency: 2.5/5.
FAQs
Does Function of Beauty custom shampoo actually work?
For many customers, yes — 4.1 stars across 27,700+ Trustpilot reviews. Results depend heavily on selecting scalp-focused goals for shampoo rather than length-focused ones. Independent reviewers describe the outcome as comparable to a good standard shampoo rather than dramatically superior.
Does Function of Beauty cause hair loss?
A 2021 VICE article reported customer complaints alleging this, and the brand’s BBB rating is very low. Function of Beauty denies the claim, citing US and EU regulatory compliance and toxicologist review. No causal link has been established publicly. If you experience unusual shedding with any hair product, discontinue use and consult a dermatologist.
How long does shipping take?
Because products are made to order, expect roughly two weeks, and reviewers report delays of three to four weeks even on repeat orders. Do not order for a deadline.
How should I fill out the hair quiz?
For shampoo, pick goals about your scalp and roots — oil control, volume, scalp care. For conditioner, pick goals about your lengths and ends — hydration, split ends, shine. Choosing length goals for shampoo is the single most common cause of disappointing results.
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