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Cleanse + Treat

The Clean Start Duo

4.9 | 339 verified reviews — Read what customers say

Theorem Serum Boost + The Grownup Cleanser™

  • Barrier-first cleansing balm that removes makeup and SPF without stripping.
  • Clinically proven collagen rebuilding for firmer skin
  • Helps to strengthen skin barrier from hormone decline
  • Proprietary fermentation process for skin longevity

$118.00

Free shipping over $45 | Easy returns | Loved by 50,000+ customers

Description

Your serum can only work on skin that is ready for it. That is the whole idea behind this pairing: a cleansing balm that respects your barrier, followed by the serum that does the heaviest lifting in your routine.

What's included in the Duo:

The Grownup Cleanser™, 200ml / 6.76 fl. oz.
A milky melting balm that goes on solid, turns to a silky oil, and lifts away makeup, SPF and the day without stripping. Calm, gentle, SLS-free and weightless.

Theorem Serum Boost, 30ml / 1 fl. oz.
Hyaluronic Molecular Nutrition and Bio-Intensified Peptide. The treatment step that supports hydration and firmness where mature skin needs it most.

Ingredients

Cleanser Ingredients: Butyrospermum Parkii Butter,Cocos Nucifera Oil (*), Helianthus Annuus Seed Oil, Aqua, Stearyl Stearate, Glycerin, Lauryl Glucoside, Cocamidopropyl Betaine, Hydrogenated Castor Oil, Copernicia Cerifera Cera, Rhus Verniciflua Peel Cera, Theobroma Cacao Butter, Oryza Sativa Bran Oil, Polyglyceryl-3 Stearate, Silica, Simmondsia Chinensis Seed Oil (*), Cucurbita Pepo Seed Extract, Tocopheryl Acetate, Sodium Ascorbyl Phosphate, Sodium Hyaluronate, Glyceryl Stearate Citrate, Phenoxyethanol, Xanthan Gum, Sodium Benzoate, Potassium Sorbate, Citric Acid.

Theorem Serum Boost Ingredients:Water, Glycerin, Propanediol, Sodium Hyaluronate, Betaine, Disodium Edetate, Hydrolyzed Sodium Hyaluronate, Jasminum Sambac (Jasmine) Flower Extract, Crataegus Monogyna Flower Extract, Yeast Extract, Tetradecyl Aminobutyroylvalyaminobutyric Urea Acetate, Caprylhydroxamic Acid, Sodium Benzoate, Soy Amino Acids, Melia Azadirachta Leaf Extract, Melia Azadirachta Flower Extract, Amino-Esters-1, Coccinia Indica Fruit Extract, Corallina Officinalis Extract

How to Use

Theorem Serum Boost:
Use 1 to 2 dropperfuls on cleansed face & neck 2 times daily. Safe for use around the eye area, pat gently onto lid & undereye. May also be used on the hands and chest.

The Grownup Cleanser™:Apply to dry skin morning and night. Massage a small amount between your fingertips and gently work into face and neck, allowing the balm to melt into an oil as it lifts away makeup and buildup.

Add water to emulsify, then rinse thoroughly.

Pro tip:Take your time here. The way you cleanse sets the tone for everything that follows.

Sizes: Theorem Serum Boost: 1 oz | 30ml — approximately 1 month supply (twice-daily use) The Grownup Cleanser™ 200ml / 6.76 fl. oz.

Dermatologist Tested | Patented Tech | Women-Founded | Created in NYC

Mature skincare Cleanser and texture shot

the grownup cleanser™

Cleanses. Softens. Restores.

The Grownup Cleanser™ is a solid-to-oil cleansing balm that removes makeup, SPF, and buildup while helping maintain your skin barrier, so your skin feels soft, not tight.

THEOREM SERUM BOOST

Plumps. Firms. Rebuilds.

Our spectrum of HA's quickly work to help make skin (and eyes) behave and look younger through healthier skin that builds itself back up.

Clinical Results

100% of women noticed softer, firmer skin in just four weeks.*
97% said their skin looked 5 years younger — without a single filter.*
100% noticed deeper, lasting hydration, not just surface-level moisture.

*Results seen after 4 weeks, 2x daily in users aged 40–69.

closeup of Theorem Serum Boost

did you know

Frequently Asked Questions

Who is the Clean Start Duo for?

Skin 40 and over, particularly anyone whose routine has quietly stopped working. If your cleanser leaves your face feeling tight, or your serum does not seem to go as far as it once did, this pairing addresses both at the same time. Formulated with mature and menopausal skin in mind.

Is Theorem Serum Boost good for sensitive skin?

Yes — it's formulated for mature, hormonally-shifting skin and is dermatologist tested.

How do I use it?

Apply morning and night to clean skin, before moisturizer.

How soon will I notice a difference?

Comfort usually changes first, often within the first few washes, because you stop stripping your barrier at step one. Hydration and firmness build with consistent use over weeks rather than days. Skincare for Grownups® works by compounding, so results come from using it regularly, not occasionally.

Can I use this alongside the rest of my routine?

Yes. Cleanse with the balm, apply Theorem to clean skin, then continue with your moisturizer, eye product or SPF as usual. If you use a retinol or other prescription treatment, keep applying it as your provider directs and layer Theorem on clean skin beforehand.

Triple Lift Molecule Mask, Grownup Moisturizer, Theorem Serum Boost Quad Set

SKINCARE FOR GROWNUPS® · THE COMPLETE ROUTINE

Skincare for Grownups®
Full-Size Quad Set

Four products. One complete routine. Built for the skin you have now. Cleanser, Serum, Moisturizer, and Mask — formulated to work together so results compound. Firmer, smoother, more hydrated skin. Faster.

Buy the full set and save $25.

Get the Quad Set