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Our Products.

The Theorem Method is a 3-part haircare system that offers a simple solution to healthier hair.
Our simple 3-part system offers lightweight, nourishing solutions that support healthy hair growth while mending
damaged, brittle hair. Resulting in thicker, longer, stronger, and healthier hair.

Can be used in conjunction with your favorite shampoo and conditioner.

Dermatologist Tested

Dermatologist Tested

Hypoallergenic

Hypoallergenic

Vegan

Vegan

Gluten-Free

Gluten-Free

No Animal Testing

No Animal Testing

Dermatologist Tested

Dermatologist Tested

Hypoallergenic

Hypoallergenic

Vegan

Vegan

Gluten-Free

Gluten-Free

No Animal Testing

No Animal Testing

Square Root

Square Root

Volumizing Root Serum.

For Fine, Thinning Hair.

Targets hair growth at the root. Thick hair begins with a healthy scalp, and this pH balanced serum plants the seed for dense, gorgeous hair. Square Root fights inflammation-related follicle narrowing, and restores pigment to gray hair naturally (with no dyes). DHT blockers inhibit hormonal hair fall and natural prebiotics promote a healthy, strong skin barrier. Also features a natural alternative to Minoxidil. Minoxidil is the only prescription hair growth ingredient that is FDA approved, but it comes with terrible side effects, which is why we use a safe and natural option instead.

Shop Now
Sugar Pi

Sugar Pi

Damage Repair Oil.

For dry, frizzy hair and split ends.

No matter how fast your hair grows, split ends are an annoying obstacle between you and your long-hair goal progress. This deeply nourishing oil revives and mends split ends, enabling you to grow your hair longer without trimming away damage so frequently. This sustainable, sugar-derived oil repairs damaged cuticles for strong, glossy, frizz-free hair. This naturally-derived, renewable complex is extracted from plant sugar, and microinjects a clinically-proven hair-healing form of Vitamin C into each hair strand to revive broken strands and split ends.

Shop Now
Density

Density

Conditioning Treatment.

For chemically treated, colored or heat damaged hair.

There’s one very important cause of hair loss that is always overlooked: hair breakage. Weak strands with damaged cuticles break easily and hair just can’t grow long or thick. Theorem Density Conditioning Treatment repairs the hair cuticle to promote hair retention. The advanced, silicon-infused formula plumps up hair strands like an injectable filler. Works synergistically with heat to strengthen and thicken hair strands, giving you the length and shine you deserve.

Shop Now
The Method

The Method

The Theorem Method is a 3-part hair care system used to achieve thicker hair from root to tip. These products take a comprehensive approach to strengthening and thickening your hair. Our formulas are precisely pH-balanced to promote a healthy scalp, follicle, cuticle, and hair cortex. Watch as the clinically-proven formulas strengthen and thicken your strands, giving you the length, shine, and fullness you desire. Best used in conjunction with each other but can be used as separate products based on your hair care needs.

Shop Now

Square Root

Volumizing Root Serum.

For Fine, Thinning Hair.

Targets hair growth at the root. Thick hair begins with a healthy scalp, and this pH balanced serum plants the seed for dense, gorgeous hair. Square Root fights inflammation-related follicle narrowing, and restores pigment to gray hair naturally (with no dyes). DHT blockers inhibit hormonal hair fall and natural prebiotics promote a healthy, strong skin barrier. Also features a natural alternative to Minoxidil. Minoxidil is the only prescription hair growth ingredient that is FDA approved, but it comes with terrible side effects, which is why we use a safe and natural option instead.

Shop now

Sugar Pi

Damage Repair Oil.

For dry, frizzy hair and split ends.

No matter how fast your hair grows, split ends are an annoying obstacle between you and your long-hair goal progress. This deeply nourishing oil revives and mends split ends, enabling you to grow your hair longer without trimming away damage so frequently.
This sustainable, sugar-derived oil repairs damaged cuticles for strong, glossy, frizz-free hair. This naturally-derived, renewable complex is extracted from plant sugar, and microinjects a clinically-proven hair-healing form of Vitamin C into each hair strand to revive broken strands and split ends.

Shop now

Density

Deep Conditioning Repair Mask.

For chemically treated, colored or heat damaged hair.

There’s one very important cause of hair loss that is always overlooked: hair breakage. Weak strands with damaged cuticles break easily and hair just can’t grow long or thick. Theorem Density Conditioning Treatment repairs the hair cuticle to promote hair retention. The advanced, silicon-infused formula plumps up hair strands like an injectable filler. Works synergistically with heat to strengthen and thicken hair strands, giving you the length and shine you deserve.

Shop now

The Method

The Theorem Method is a 3-part hair care system used to achieve thicker hair from root to tip. These products take a comprehensive approach to strengthening and thickening your hair. Our formulas are precisely pH-balanced to promote a healthy scalp, follicle, cuticle, and hair cortex. Watch as the clinically-proven formulas strengthen and thicken your strands, giving you the length, shine, and fullness you desire. Best used in conjunction with each other but can be used as separate products based on your hair care needs.

Shop now

Testimonials

Raquel S.

"Wow’d by the softness of my hair after using it once! "

Tiffany M.

"Smells amazing."

Jess V.

"Smells really good- love how my hair feels after one use."

Hannah L.

"I loved the way it feels on my hair. Super easy to brush through after the shower."

Alissa

"AMAZING PRODUCT! "

Valerie V.

"Loved it - using it since 03/2020"

Rebecca B.

"Loved it - using it since 03/2020"

Alex

"The smell was amazing! Hair was noticeably soothed."

Allison M.

"Loved the way the hair effortlessly blow dried out and have great shine."

Brooke D.

"My long hair is such a pain to brush and after one use I noticd it was smooth and much easier to comb through."

60-Days Guarantee

60-Days Guarantee

We have so much faith in our products that we offer a 60-day, no quibble, money-back guarantee. If you don’t love our products, just send it back to us for a full refund.

Shipping

Shipping

Once your order is confirmed shipped, you will receive your items in 5-7 business day.

Free Shipping

Free Shipping

Spend $50 or more
and shipping is on us!

60-Days Guarantee

60-Days Guarantee

We have so much faith in our products that we offer a 60-day, no quibble, money-back guarantee. If you don’t love our products, just send it back to us for a full refund.

Shipping

Shipping

Once your order is confirmed shipped, you will receive your items in 5-7 business day.

Free Shipping

Free Shipping

Spend $50 or more
and shipping is on us!

Square Root
TH1

Square Root

Volumizing Root Serum.

For Fine, Thinning Hair.

  • Description
  • Ingredients
  • Directions

Thick hair begins with a healthy scalp, and this pH balanced serum plants the seed for dense, gorgeous hair. Square Root Serum nourishes your roots and restores pigment to gray hair naturally (with no dyes). DHT-blockers inhibit hormonal hair fall and natural prebiotics promote a healthy scalp. This is a safe, natural alternative to Minoxidil (hair loss drug).

Ingredients: Water (Aqua), Polysorbate 20, Hydrolyzed Lupine Protein, Lactobacillus Ferment, Melaleuca Alternifolia (Tea Tree) Leaf Water, Sodium Hyaluronate, Glycerin, Yeast Extract, Acetyl Tyrosine, Glycine, Larix Europaea Wood Extract, Zinc Chloride, Panthenol, Caffeine, Glucosamine HCl, Aloe Barbadensis Leaf Juice, Rosa Damascena Flower Water, Camellia Sinensis Leaf Extract, Hamamelis Virginiana (Witch Hazel) Bark/Leaf/Twig Extract, Serenoa Serrulata Fruit Extract, Arginine HCl, Sodium Metabisulfite, Menthyl Lactate, PEG-40 Hydrogenated Castor Oil, PPG-26-Buteth-26, Maltodextrin, Fragrance, Phenoxyethanol, Ethylhexylglycerin, Sodium Benzoate, Potassium Sorbate, Sodium Hydroxide, Benzyl Salicylate, Limonene, Hexyl Cinnamal, Hydroxycitronellal, Linalool, Alpha-Isomethyl Ionone

Directions: Use targeted sprayer to direct the product at your roots. Use daily. Massage in well for best results. Due to volumizing and thickening ingredients, your hair may dry with a thickening film. If you have fine or straight hair, release the film by brushing dry hair at the roots with a fine bristle brush. If you have curly hair, loosen with a wide tooth comb or fingers once dry. This will help volumize your roots.

Subscribe & Save!

Receive a 30-day supply of Square Root each month for $29.99
Commit to a Monthly Subscription which enrolls you Theorem Preferred Customer
Club with great benefits.
Save 10% on today's order + Save 10% on all future orders.

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100% Satisfaction Guaranteed. Free Shipping + Returns.

Dermatologist Tested

Dermatologist Tested

Hypoallergenic

Hypoallergenic

Vegan

Vegan

Gluten-Free

Gluten-Free

No Animal Testing

No Animal Testing

Dermatologist Tested

Dermatologist Tested

Hypoallergenic

Hypoallergenic

Vegan

Vegan

Gluten-Free

Gluten-Free

No Animal Testing

No Animal Testing

How does it work?

Square Root supplies oxygen and nutrients to vascular system to support & revise the dying follicle. Restores pigment to gray hair naturally (with no dyes) over time for thicker looking hair. Square Root also fights inflammation . Ever seen hair grow on a scar? It can't, because the hair follicles have scarred over from inflammation. The same thing happens if your scalp is inflamed. Follicles grow narrower and narrower until hair can no longer grow.

Before and After

Testimonials

Raquel S.

"Wow’d by the softness of my hair after using it once! "

Tiffany M.

"Smells amazing."

Jess V.

"Smells really good- love how her hair feels after one use."

Hannah L.

"I loved the way it feels on my hair. Super easy to brush through after the shower."

Alissa

"AMAZING PRODUCT! "

Valerie V.

"Loved it - using it since 03/2020"

Rebecca B.

"Loved it - using it since 03/2020"

Alex

"The smell was amazing! Hair was noticeably soothed."

Allison M.

"Loved the way the hair effortlessly blow dried out and have great shine."

Brooke D.

"My long hair is such a pain to brush and after one use I noticd it was smooth and much easier to comb through."

60-Days Guarantee

60-Days Guarantee

We have so much faith in our products that we offer a 60-day, no quibble, money-back guarantee. If you don’t love our products, just send it back to us for a full refund.

Shipping

Shipping

Once your order is confirmed shipped, you will receive your items in 5-7 business day.

Free Shipping

Free Shipping

Spend $50 or more
and shipping is on us!

60-Days Guarantee

60-Days Guarantee

We have so much faith in our products that we offer a 60-day, no quibble, money-back guarantee. If you don’t love our products, just send it back to us for a full refund.

Shipping

Shipping

Once your order is confirmed shipped, you will receive your items in 5-7 business day.

Free Shipping

Free Shipping

Spend $50 or more
and shipping is on us!

Discover More

Sugar Pi

Damage Recovery Oil.

Shop now

Density

Deep Conditioning Repair Mask.

Shop now

The
Method

Shop now
Square Root
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Square Root
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