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Clinically Proven Firming Serum
When skin changes after 40, this is the face + eye serum built for it.
$34.00
Free shipping over $45 | Easy returns | Loved by 50,000+ customers
Theorem Serum Boost is Caire Beauty's all-in-one face, eye, neck, and chest serum, built for the hormonal skin changes that begin in your late 30s and continue through menopause — when declining estrogen slows your skin's own production of hyaluronic acid and collagen.
Your skin didn't stop working. It stopped getting what it needs. Theorem Serum Boost gives it back: a triple-weight hyaluronic acid complex that hydrates at every layer, paired with bio-fermented peptides that signal your skin to rebuild collagen on its own. In clinical testing, 97% of women saw skin that looked up to five years younger, and 100% saw softer, firmer skin within four weeks.*
This is not surface moisture. It's skin health support, formulated for women whose skin has started to change — and tested on skin like yours, not skin half your age.
*Results after 4 weeks, twice-daily use, women ages 40–69.
Theorem Serum Boost is formulated with four ingredients, each chosen for what hormonally changing skin specifically needs:
Triple-weight hyaluronic acid — three different molecular weights layer hydration from the surface down to as deeply as it can, instead of sitting on top like a single HA weight formula.
Bio-fermented peptides — One of the only brands to ferment our signaling peptides, to help create smaller molecules your skin can actually absorb more efficiently and effectively. Made through Caire's proprietary fermentation process, so they help reach the layers where new collagen is actually built.
Arabian jasmine — chosen specifically for the eye area, where most actives get diluted down or left out entirely. It works on melanin buildup directly, which is one of the two real causes of dark circles (the other is blood pooling — that's hawthorn's job, below).
Hawthorn berry extract — works alongside jasmine on the actual mechanics of dark circles: the leaky capillaries that let blood pool under the eyes in the first place. It's the reason the under-eye area looks bluish-purple, not just discolored.
Together, this pairing is Theorem Serum Boost's real standout for eye-area performance.
Clean, vegan, fragrance-free, and hormone-safe.
Apply Theorem Serum Boost twice daily, morning and night: 1–2 dropperfuls pressed lightly into clean, slightly damp skin.
Press gently into the face, around the eyes (including lids and under-eye), neck, chest, and even the backs of hands — anywhere you're noticing change. Use before any other non-Hyaluronic Acid or Peptide serums, moisturizer, retinol, facial oil, or other treatments.
With consistent twice-daily use, skin appears smoother, firmer, more hydrated and youthful over time.
Sizes: 1 oz | 30ml — approximately 1 month supply (twice-daily use) 0.5 oz | 15ml — approximately 2 weeks supply (twice-daily use)
Dermatologist Tested | Patented Tech | Women-Founded | Created in NYC
Specifically designed to address issues related to hormone depleted skin.
Fermented peptides small enough to actually reach the layers where new collagen is built.
Dr. Beth Goldstein uses our serum herself. She doesn't recommend things lightly.
Key Benefits
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
*Results seen after 4 weeks, 2x daily in users aged 40–69.
WHY THIS WORKS
The skin you have today requires a different kind of support. Theorem Serum Boost pairs advanced hyaluronic acidtechnology with fermented peptidesto restore hydration and promote the appearance of firmness, elasticity, and bounce.
Before After Clinically shown to help skin appear up to 5 years younger*
Fran, 56. 18 days. Theorem Serum Boost + Triple Lift Molecule Mask.
Real customer. Her own results.
Individual results may vary.
In a 4-week clinical study, participants reported skin appeared up to 5 years younger.*
*Separate clinical study conducted. Full methodology at cairebeauty.com/science. Individual results may vary.
did you know
Most see smoother, more hydrated skin within 2–3 days, with firmer, plumper skin building over 4 weeks of twice-daily use.
Yes — it's formulated for mature, hormonally-shifting skin and is dermatologist tested.
Apply morning and night to clean skin, before moisturizer.
Yes — it's built as a face + eye serum.
Hormonal skin—especially during perimenopause and menopause—absorbs moisture more slowly. Apply Theorem Serum Boost to slightly damp skin and gently press it in, including around the eyes, to help optimize hydration delivery and absorption.
The Caire Ritual
Cleanse
Balm-to-oil formula nourishes while cleansing.
$72.00
Restore
Patented CeraLipids® barrier repair.
$42.00
Amplify
Spa-grade firming in 15 minutes.
$36.00
I'm 51 and I have had good skin my whole life until perimenopause, when I began getting stubborn acne. Within 2–3 days of using the serum, I noticed my acne beginning to clear up.
My hygienist had to double-check my date of birth. She couldn't believe I was 60.
Better than Shiseido and Lancôme serums. I've been using facial serums for 14 years, and Caire's was immediately absorbed by my skin.
SKINCARE FOR GROWNUPS® · THE COMPLETE ROUTINE
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