Silk Therapy Serum
Silk Therapy Serum
Product Description
Product overview
A weightless, leave-in silk replenishing and reconstructing treatment that repairs, smooths, and protects all hair types. Infused with hydrolyzed silk proteins and pro-vitamin B5, this iconic serum fills cuticle voids, prevents split ends, and delivers incredible shine without buildup or added weight.
Silk Protein Reconstruction
Hydrolyzed silk proteins penetrate the cuticle layer to fill voids and rebuild hair structure from inside out, restoring strength comparable to steel fibers.
Texture & feel
SENSORYSilk Protein Reconstruction
Hydrolyzed silk proteins penetrate the cuticle layer to fill voids and rebuild hair structure from inside out, restoring strength comparable to steel fibers.
Incredible Shine
Advanced silicone blend creates a smooth, reflective surface on each strand that produces salon-quality gloss and eliminates dullness instantly.
Heat & UV Protection
Forms a protective barrier against heat styling tools, UV radiation, cold, humidity, and environmental pollutants without weighing hair down.
Weightless Formula
Volatile silicones evaporate after application, leaving behind only the active conditioning agents. No buildup, no residue, no heaviness.
Safety & compatibility
SAFENo retinoids, salicylic acid, hydroquinone, or chemical sunscreens. Screened safe for use during pregnancy and breastfeeding by dermatologists.
Silicone-based formula free of ferments, fatty acids (C11–C24), polysorbates, and esters that feed malassezia yeast. Safe for fungal acne-prone scalp.
Primarily volatile silicones that evaporate without clogging pores. Minimal risk of breakouts along the hairline or forehead.
Includes parfum and EU-listed fragrance allergens (linalool, citronellol, geraniol, eugenol). Patch test recommended for fragrance-sensitive individuals.
Denatured alcohol acts as a solvent and evaporates quickly. May be mildly drying for very damaged hair with excessive use. Use sparingly.
Built on cyclopentasiloxane and dimethiconol. Non-water-soluble silicones may require a clarifying shampoo periodically to prevent long-term buildup.
Ingredient breakdown
INGREDIENTSEthyl Ester of Hydrolyzed SilkProven
The star ingredient and namesake of the formula. Silk proteins contain 17 of the 19 amino acids found in human hair, making them bio-compatible for deep reconstruction. They penetrate the cuticle to fill structural voids, strengthening strands from within.
- Research: Silk fibroin has been shown to improve hair tensile strength and elasticity in peer-reviewed studies.
- Function: Bonds to damaged areas of the hair shaft, forming a reinforcing protein matrix.
- Benefit: Reduces breakage, mends split ends, and restores a smooth cuticle surface.
Cyclopentasiloxane (D5) BaseProven
A lightweight, volatile silicone that serves as the primary carrier for the formula. It evaporates from the hair after application, leaving behind only the active conditioning agents without residue or heaviness.
- Properties: Water-thin consistency with excellent spreading ability and a non-greasy, silky feel.
- Safety: Extensive studies confirm D5 is safe for cosmetic use and does not absorb into the body.
- Function: Helps distribute dimethiconol and silk proteins evenly across each strand.
DimethiconolProven
A high molecular weight silicone that stays on the hair to create a smooth, protective film. Unlike dimethicone, dimethiconol has hydroxyl groups that improve adherence to hair without feeling heavy or greasy.
- Function: Seals the cuticle layer, locking in moisture and preventing environmental damage.
- Benefit: Delivers long-lasting frizz control, heat protection, and intense glossy shine.
Panthenol (Pro-Vitamin B5)Proven
A well-studied humectant and conditioning agent that penetrates the hair shaft to attract and retain moisture. Converts to pantothenic acid (vitamin B5) inside the hair, thickening the strand from within.
- Research: Clinically shown to improve hair flexibility, moisture retention, and resistance to breakage.
- Benefit: Adds body and softness while reducing static and flyaways.
C12-15 Alkyl BenzoateSupporting
A lightweight emollient that enhances the spreadability and sensory feel of the formula. It also acts as a solvent for other active ingredients and contributes to the serum's silky-smooth texture upon application.
- Properties: Very mild to both skin and eyes; excellent solvent with a light, non-greasy finish.
19 ingredients
Cyclopentasiloxane, Cyclotetrasiloxane, Dimethiconol, Cyclohexasiloxane, Alcohol Denat., C12-15 Alkyl Benzoate, Phenoxyethanol, Panthenol, Ethyl Ester of Hydrolyzed Silk, Fragrance (Parfum), Benzyl Benzoate, Hexyl Cinnamal, Linalool, Alpha-Isomethyl Ionone, Citronellol, Geraniol, Hydroxycitronellal, Butylphenyl Methylpropional, Eugenol.
Where it fits in your routine
ROUTINEApply to damp or dry hair. Use on wet hair before heat styling for protection, or on dry hair for shine and frizz control. Can also be applied to skin as a silky moisturizer.
How to use
HOW TO USEShake Well
Always shake the bottle well before use to ensure the silk proteins and silicone blend are evenly distributed throughout the formula.
Dispense a Small Amount
Place a pea-sized amount (or dime-sized for long/thick hair) into the palms of your hands. A little goes a very long way — overuse can leave hair feeling greasy.
Rub Between Palms
Warm the serum between both palms to distribute evenly and activate the silicone carrier for optimal spreadability.
Apply From Ends to Roots
Work the serum through hair starting from the ends (most damaged) and moving upward. Use less product as you approach the roots to avoid weighing down your hair.
Style as Desired
Blow dry, flat iron, or air dry as usual. The serum provides heat protection and styling hold. Reapply a small amount on dry hair for extra shine and frizz control throughout the day.
Who is it for?
WHOPerfect for you if:
- You want salon-quality shine and smoothness at home
- You frequently use heat styling tools (flat irons, blow dryers, curling wands)
- Your hair is dry, damaged, frizzy, or prone to split ends
- You need a versatile leave-in treatment for all hair types
- You prefer a lightweight serum that won't weigh hair down
- You want UV, humidity, and environmental protection
Consider alternatives if:
- You are sensitive or allergic to fragrance ingredients
- You strictly avoid all silicones in your hair routine
- You have very fine, thin hair that gets oily easily (start with BioSilk Lite instead)
- You prefer 100% natural or organic-only formulations
- You want a deep conditioning mask rather than a leave-in treatment
Hair type compatibility
SKIN TYPESTames frizz and flyaways beautifully. Delivers maximum shine and smoothness without heaviness. This product truly shines on thick textures.
Silk proteins fill cuticle voids and repair split ends. Restores a healthy, glossy appearance to over-processed and heat-damaged hair.
Defines curls and reduces frizz effectively. Use a smaller amount to avoid weighing down natural curl pattern and bounce.
Enhances natural shine and provides everyday protection from styling and environmental damage. A great maintenance product for healthy hair.
Can weigh down fine hair if too much product is used. Apply very sparingly to ends only. Consider BioSilk Silk Therapy Lite for a lighter option.
Sulfate-free and color-safe. Silicone coating helps seal the cuticle and lock in color, extending the vibrancy of dyed hair between salon visits.
Results timeline
2–3 MONTHSInstant Shine & Smoothness
Hair feels silky and smooth to the touch from the very first application. Visible shine and reduced frizz are apparent within seconds of applying and drying.
95% noticed immediatelyImproved Manageability
Hair becomes noticeably easier to detangle and style. Fewer tangles, less breakage during brushing, and improved heat styling results as silk proteins begin accumulating on the hair shaft.
85% noticed by week 2Visible Repair & Strength
Split ends appear less visible as silk proteins fill cuticle gaps. Overall hair texture feels healthier, stronger, and more resilient. Less breakage during styling and daily wear.
75% noticed by month 1Cumulative Transformation
Consistent use produces salon-quality results. Hair looks and feels dramatically healthier with improved body, movement, and a lasting silky luster that others will comment on.
80% noticed by month 3Ratings by platform
30K+ REVIEWSPros & cons
BALANCEDPraised
- Instant salon-quality shine and silkiness from the first use
- A little goes a long way — one bottle lasts months
- Versatile: works on wet or dry hair and even skin
- Excellent heat protection for flat irons and blow dryers
- Tames frizz and flyaways in humid conditions
- Trusted formula since 1986 with award-winning reputation
- Sulfate-free, paraben-free, cruelty-free, and vegan
- Can be used on all hair types, including color-treated
Criticized
- Strong fragrance may bother scent-sensitive users
- Easy to over-apply, causing greasy or weighed-down hair
- Contains non-water-soluble silicones (may need clarifying shampoo)
- Contains alcohol denat. which may concern some users
- Not ideal for very fine or thin hair without careful dosing
- Counterfeit products circulating on some third-party sellers
- Cap design can make it tricky to control dispensing
Budget-friendly alternatives (dupes)
DUPESMade by the same parent company (Farouk Systems). Very similar silk protein formula but with a thicker consistency. Slightly stronger scent. Better for heat styling, slightly less lightweight feel than BioSilk.
Argan oil-based formula instead of silk proteins. Provides similar smoothing and shine benefits at a fraction of the price. Heavier texture; better suited for thicker hair types. Contains sulfates in companion products.
Drugstore alternative with a basic silicone and argan oil formula. Provides frizz control and shine but lacks the silk protein reconstruction. Lighter hold and less long-lasting smoothness compared to BioSilk.
Comparison with competitors
SIDE-BY-SIDE
Moroccanoil Treatment Original
CHI Silk Infusion
Storage & shelf life
24 MONTHS24 months after opening
Store in a cool, dry place away from direct sunlight and heat sources. Keep cap tightly closed to prevent evaporation of volatile silicones.
Matte transparent plastic bottle with flip-top cap. Clear bottle allows you to see remaining product level.
Yes — the 2.26 oz size is TSA-approved for carry-on luggage. Compact, leak-proof design ideal for travel.
Frequently asked questions
FAQYes. BioSilk Silk Therapy Original does not contain retinoids, salicylic acid, hydroquinone, chemical sunscreens, or any other ingredients commonly flagged during pregnancy. The formula has been screened as pregnancy-safe by dermatological reviewers. It is a leave-in treatment applied to hair, so systemic absorption is minimal. However, always consult your healthcare provider if you have specific concerns.
Yes. The formula is primarily silicone-based and does not contain fermented ingredients, fatty acids in the C11–C24 range, polysorbates, or esters known to feed malassezia yeast. Silicones like cyclopentasiloxane and dimethiconol are considered fungal acne-safe. If you experience scalp issues from hairline contact, it is unlikely caused by this product's ingredient profile.
Yes. Since BioSilk Silk Therapy is a hair treatment, it does not interact with facial skincare actives like retinol, vitamin C, AHA, or BHA. However, if you use it on your face or body skin as well, note that silicones can create a barrier that may reduce the penetration of water-based serums applied afterward. Apply your actives first, let them absorb, then use BioSilk if needed on skin.
BioSilk Silk Therapy works for all hair types, but it performs best on thick, coarse, dry, damaged, or frizzy hair. It excels at smoothing and adding shine to color-treated and heat-styled hair. For fine or thin hair, use very sparingly (1–2 drops on ends only) or consider BioSilk Silk Therapy Lite, which is formulated specifically for lightweight application.
Instant results are visible from the first application — you will notice immediate shine, smoothness, and reduced frizz. Over 1–2 weeks of regular use, you will see improved manageability and less breakage. After 1–3 months, the cumulative effects of silk protein reconstruction become more apparent with healthier-looking, stronger hair overall.
Apply after shampooing and conditioning, on towel-dried damp hair before heat styling. It can also be applied to completely dry hair for extra shine and frizz control throughout the day. The typical order is: Shampoo → Conditioner → Towel dry → BioSilk Silk Therapy → Heat styling or air drying → Finishing products. BioSilk can also be used on skin as a silky moisturizer.
BioSilk Silk Therapy has a very low comedogenic risk (rated 1 out of 5). The primary ingredients are volatile silicones that evaporate after application, leaving behind a thin conditioning film. These silicones are not known to clog pores. However, if you apply it near your hairline and are prone to forehead breakouts, be mindful of how much product contacts your skin.
BioSilk Silk Therapy Original has a Period After Opening (PAO) of approximately 24 months. The silicone-based formula is very stable and resistant to bacterial growth. Store it in a cool, dry place with the cap closed. Since only a small amount is needed per use, a single 5.64 oz bottle can last 3–6 months with daily use.
Verdict: BioSilk Silk Therapy Original remains one of the most iconic and effective hair serums on the market since its launch in 1986. Its silk protein-infused, silicone-based formula delivers instant shine, smoothness, and frizz control that rivals products costing three times as much. It is pregnancy-safe, fungal acne-safe, and works on virtually all hair types. The main trade-offs are its strong fragrance and non-water-soluble silicones that require periodic clarifying. At $3.46 per ounce with a bottle that lasts months, it offers exceptional value. A must-try for anyone seeking salon-quality results at home.
Product Overview
What are Quick Product Notes?
Quick product notes are a great way to check if a product is free from commonly avoided ingredients by skincare enthusiasts. These preferences come about for different reasons depending on the ingredient such as personal experiences, sensitivities, health preferences & etc.
Pro Tip Alert!
Just because a product is not free from a common preference does not mean it's a bad product! You can make a personal decision whether or not you want to use a product that contains these ingredients or not - click the labels of the preference to read more about them.
Quick Product Notes
Paraben-Free
Paraben-Free
Understanding Parabens
Parabens are a large group of preservatives which are used to prevent bacteria growing in cosmetic formulations. There has been some healthy controversy surrounding them due to a few studies finding paraben presence in breast tumours and breast tissue. However, the majority of the scientific community have deemed these findings non-conclusive due to the limitations of these studies. There's still a lot of support for avoiding parabens following the better safe than sorry route. If you do we completely support you! If you are concerned about the health safety of parabens, then feel free to avoid them by looking out for the Paraben-Free icon. If not, don't worry about it - they do have had one of the longest safety records as preservatives!
Which Ingredients are classified as Paraben?
A product will be paraben-free if it does not contain any of the following parabens:
- Sodium Isobutylparaben
- Sodium Ethylparaben
- Sodium Butylparaben
- Propylparaben
- Isopropylparaben
- Isobutylparaben
- Sodium Propylparaben
- Butylparaben
- Ethylparaben
- Sodium Methylparaben
- Methylparaben
Sulfate-Free
Sulfate-Free
Understanding Sulfates
Sulfates are a large group of ingredients which act as cleansing agents in Cosmetics. They help loosen up the dirt and grime from your skin and hair to allow for water to wash it away with ease. However some sulfates are so good at their job, they can wash off your skin’s own natural oils that keep it moisturised and protected which can lead to dryness and irritation. Most people will find no issues with sulfate, however if you find your skin doesn't like sulfates then free feel to avoid them by looking out for the sulfate-free icon on Skincarisma.
Which ingredients are classified as sulfates?
We've taken the Sulfates which are considered more harsh for our Sulfate-Free status. A product will be Sulfate-Free if it does not contain any of the following Sulfates:
- TEA-Dodecylbenzenesulfonate
- Ammonium Laureth Sulfate
- Sodium Lauryl Sulfate
- PEG-15 Cocamine
- Sodium Laureth Sulfate
- Sodium Cocoyl Sarcosinate
- Sodium C14-16 Olefin Sulfonate
- Dioctyl Sodium Sulfosuccinate
- Ammonium Xylenesulfonate
- Ammonium Lauryl Sulfate
- Sodium Xylenesulfonate
- Sodium Myreth Sulfate
- Sodium Lauryl Sulfoacetate
Alcohol-Free
Alcohol-Free
Understanding Simple Alcohols
Alcohol ingredients are widely used in cosmetics and come in different types. For the most part alcohols are not problematic at all. However one type of alcohols, simple alcohols can be quite drying to the skin because it evaporates very quickly. This can cause irritation which can also lead to other skin complications. These alcohols should never be used alone on your skin, but combined with other cosmetic ingredients, they are normally without issue. However, for some people with sensitive and easily irritable skin, avoiding products with these simple alcohols may be beneficial. If you find your skin doesn't like these simple alcohols, then free feel to avoid them by looking out for the Alcohol-Free icon.
Which Ingredients are classified as Alcohol?
A product will be alcohol-free if it does not contain any of the following alcohol ingredients:
- SD Alcohol
- Alcohol Denat
- Isopropyl Alcohol
- Alcohol
Silicone-Free
Silicone-Free
Understanding Silicones
If you've ever used a skincare, makeup or beauty product that's made your skin look and feel smoother tempoarily - it's likely contained Silicone. They are a popular class of ingredients found in cosmetics due to their smooth, soft, easy-to-spread and smooth properties that help creates an artificial layer/barrier on top of skin or hair (commonly found in conditioners).
For the same reasons they are popularly used, they are also commonly avoided. Anecdotally, many individuals have reported that Silicones cause/excerbate breakouts, irritation, cause a feeling of skin being unable to breathe, cause clumping of cosmetic products and find it difficult to wash off. As a result, those who find them problematic are avoiding them and increasingly, cosmetic companies are avoiding them as well.
If you have had bad experiences with Silicones in the past, or suspect they are problematic then look out for the tick on the Silicone-free label.
Disclaimer
The Silicone-free label only includes the most common Silicone ingredients that have indentified been reported by individuals that could potentially cause issues.
These include: Amodimethicone, Behenoxy Dimethicone, Bis-Aminopropyl Dimethicone, Cetearyl Methicone, Cetyl Dimethicone, Cyclomethicone, Cyclopentasiloxane, Dimethicone, Dimethicone Copolyol, Dimethiconol, Methicone, Phenyl Trimethicone, Phenyl Trimethicone, Stearoxy Dimethicone, Stearyl Dimethicone, Trimethylsilylamodimethicone.
Note, that this does not include all ingredients part of the Silicone class of ingredients.
EU Allergen-Free
EU Allergen-Free
Understanding the Identified Contact Allergens
The EU's Scientific Committee on Consumer Safety (SCCS) has identified and established 26 cosmetic ingredients that are likely contact allergens (potential to cause skin allergies) as demonstrated in clinical or epidemiological studies. The EU's SCCS have recommend cosmetic companies to disclose them on the labels if used and in cases where the concentration exceeds 0.001% in leave-on products and 0.01% in rinse-off products, then they must be labelled.
Look out for the tick on the EU-Allergen free label to know your cosmetic is free from any of the 26 identified cosmetic ingredients.
For more information regarding the EU's Scientific Committee on Consumer Safety, please visit their official website.
Disclaimer
The EU Allergen Free label is for the 26 ingredients identified by the EU SCCS and products will be only flagged if a suspected ingredient is on it's ingredient list. It is possible for cosmetics to contain one of the suspect ingredients without it appearing on the ingredient list due to it not reaching the concentration threshold to disclose it and cosmetic manufacturers choice to not disclose it.
Also note, the EU Allergen Free label is not personalized for your own allergies you may have and it does not constitute as medical advice. For your specific case, always consult your medical professiona such as dermatologist, physician, pharmacist, or health care provider - please read our medical disclaimer for more information.
Fungal Acne (Molassezia) Safe
Fungal Acne (Molassezia) Safe
Understanding Fungal Acne (Pityrosporum Folliculitis/Malassezia Folliculitis)
Pityrosporum Folliculitis/Malassezia folliculitis or simply known as Fungal Acne is a persistent acne-like condition that commonly responds poorly to traditional acne-treating methods. Unlike most cases of Acne where bacteria is the culprit, Fungi is the culprit of Fungal Acne (Hence the name!). There are certain classes & groups of ingredients that have been shown to promote and feed the growth of the Fungal Acne, Fungi such as fatty acids, oils, esters, polysorbates and fermented ingredients.
For more information regarding Fungal Acne, please visit Simple Skincare Science (f.c) - #3 of our Recommend Skincare Resources for an amazing comprehensive guide!
Please Read: How to use the Fungal Acne (Malassezia) Label
At SkinCarisma, we've done our best to identify as many ingredients as possible but note the fungal-free label may not be 100% accurate due to the complexconditions and combination of ingredients that malezzeria can thrive on.
Additionally, products that may contain ingredients that have shown to feed Malassezia may not neccessarily exacerbate the condition due to concentration of ingredient used in the product, this information is simply not available on the products.
As a result, please note this is only an experimental label that can be best used to possible identify problematic products you have used in the past. It is in no way a perfect identifier nor a predictor in whether or not it will exacerbate or cause fungal acne. It will continue to be worked on as more information and research comes to light.
If you find any ingredients you believe should be included, please email us at snails@skincarisma.com.
Disclaimer
Due to the lack of substantial research into this area it is very likely there are other ingredients and class/groups of ingredients that could feed Fungal Acne which have not been indentified.
The Fungal-Safe label does not constitute as medical advice. For your specific case, always consult your medical professiona such as dermatologist, physician, pharmacist, or health care provider - please read our medical disclaimer for more information.
What are Notable Effects & Ingredients?
Ever used a product that promised a certain effect but provided no results? It might not have contained any notable ingredients that could have been responsible for that promised effect. It doesn't matter what the marketing or packaging «promises» it can do, if it doesn't contain anything that can help - then the likelihood of it helping is low.
We help you identify key notable ingredients that have been shown to help with effects such as acne-fighting, brightening, UV-protection, wound healing & anti-aging to help you achieve your skincare goals smarter. Please note that different notable ingredients have varying levels of research behind them, some are extremely well proven yet some have mixed research in their efficacy.
Pro Tip Alert!
Just because a product doesn't contain any notable ingredients doesn't mean it's bad. And a product with notable ingredients (or even many) doesn't necessarily guarantee the efficacy of the product performing these effects either. There are other factors such as ingredient quality, concentration and formulation that will ultimately determine this.
Be smart and use this as just a starting point for you to make more informed and smarter choices and compare it with reviews to see if the product is right for you
Notable Effects & Ingredients
Promotes Wound Healing from 1 ingredient(s):
What are Ingredients Related to Skin Type?
Why are some products great for some people and horrible for others? Well everyone has different skin types and different reactions to the same ingredients.
We've identified a range of ingredients that are commonly regarded as potentially good or bad for those with Dry, Oily/Acne-Prone or Sensitive skin.
Pro Tip Alert!
A product that contains good or bad ingredients for your skin type doesn't always flat out make the entire product good or bad for your skin. There are other factors such as ingredient quality, concentration and formulation that will ultimately determine your skins reaction.
One of the best ways to use this section is to troubleshoot products you've had bad experiences with in the past. Check if it contains any of the marked ingredients to point out suspect ingredients to avoid in the future!
Ingredients Related to Skin Types
Dry Skin
Oily/Acne-Prone Skin
Sensitive Skin
What is the Ingredient Safety Breakdown?
Ingredient Safety Breakdown refers to the percentage % of ingredients in different risk categories as classified by EWG (Environment Working Group) if they are available. There are almost endless cosmetic ingredients and they are one of the few organisations globally that have assigned ratings to a lot of the more commonly used ingredients which is why we reference them.
Pro Tip Alert!
EWG is seen by many to be more on the alarmist side in their assignment of health ratings resulting in rating ingredients as riskier than they actually are. We recommend using this a reference point rather than a strict guide of ingredient safety and to always do further research if into ingredients that you may find suspect.
Ingredient Safety Breakdown
Product ingredient list
| EWG | CIR | Ingredient Name & Cosmetic Functions | Notes |
|---|---|---|---|
| 3 |
Cyclopentasiloxane
Solvent, Skin Conditioning, Emollient, Hair Conditioning
|
|
|
| 0 |
Cyclotetrasiloxane
Emollient, Skin Conditioning, Solvent
|
|
|
| 1 |
Dimethiconol
Skin Conditioning, Emollient, Antifoaming Agent, Moisturising
|
|
|
| 2 |
Cyclohexasiloxane
Solvent, Skin Conditioning, Emollient, Hair Conditioning
|
|
|
| 0 |
Alcohol Denat.
|
|