Best Non-Toxic Hair Straightener & Smoothing Treatment in 2025
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What we look for:
- Simple formulations using fully natural or safe synthetic ingredients
- No parabens, PEGs, phthalates, harsh sulfates, BHA/BHT, artificial dyes, formaldehyde or formaldehyde releasers, or undisclosed synthetic fragrance (unless certified safe)
- Minimal, necessary preservatives only
- Trusted third-party certifications when available
- Transparent sourcing, ingredients, and manufacturing practices
Not all products in this category are Welpr Approved, but they’re safer than most. The ones that meet our full standard will have the Welpr Approved tag. View our full standards here.
Find Non-Toxic Hair Straightener & Smoothing Treatment
Multi-Tasking Oil for Smooth Hair and Skin - SheaMoisture
Product Details
- Rich in essential fatty acids and vitamin E for nourishing skin and hair.
- Controls frizz and adds a healthy shine to hair when used as a serum.
- Quickly absorbs to soften and smooth dry skin and hair.
- Replenishes moisture for a youthful skin glow.
- Formulated without sulfates, parabens, phthalates, mineral oil, or petrolatum.
Pros & Cons
Pros
- Leaves hair and skin feeling soft, moisturized, and shiny.
- Great for multi-purpose use on hair, face, and hands.
- Absorbs well without leaving a greasy residue.
- Pump top design makes dispensing easy and convenient.
Cons
- Some users found the scent less appealing.
- Issues with packaging and delivery noted by a few users.
Ingredients
Ingredients: 100% Argan Oil
Smoothing Hair Balm - Rahua
Product Details
- Tame unruly strands and flyaways instantly with smooth, polished results for quick daily touch-ups.
- Offers flexible hold for styles like sleek ponytails, curls, and spikes on all hair types.
- Non-sticky and non-greasy formula provides effective hold without feeling heavy.
- Perfect for taming baby hairs and frizz while maintaining a soft, touchable texture.
- Keeps your style fresh all day with long-lasting control without hardening or flaking.
Pros & Cons
Pros
- Effectively tames fly-aways and maintains hairstyles all day.
- Leaves hair perfectly controlled and sculptable.
- Comes with a pleasant scent that users enjoy.
Ingredients
Ingredients: Organic Helianthus Annuus (Sunflower) Seed Oil, Blend of Hydrogenated Cocos Nucifera (Coconut), Brassica Campestris (Rapeseed) and Helianthus Annuus (Sunflower) Oils, Organic Salvia Sclarea (Clary Sage) Oil, Organic Theobroma Cacao (Cocoa) Seed Butter, Organic Cocos Nucifera (Coconut) Fruit Oil, Oenocarpus Bataua (Rahua Ungurahua) Oil, Plukenetia Volubilis (Sacha Inchi) Seed Oil, Mauritia Flexuosa (Morete) Fruit Oil, Organic Rosmarinus Officinalis (Rosemary) Leaf Extract, Gard
Control Curl Cream Styler - Rahua
Product Details
- Formulated with plant-based ingredients for soft, touchable curls.
- Provides moisture with shea butter and molasses, adding definition and flexibility.
- Lightweight hold helps manage frizz and maintain desired curl shape.
- Sulfate and paraben free, ensuring a non-toxic hair care experience.
- Contributes to a sustainable future by helping preserve the Amazon Rainforest.
Pros & Cons
Pros
- Great smell that appeals to those with sensitivity.
- Keeps curls together and frizz down without heaviness.
- Well-suited for fine, wavy, or curly hair types.
- Leaves hair soft and manageable.
Cons
- May not provide enough moisture for very dry hair types.
- Effectiveness could vary, offering limited results for some users.
Ingredients
Ingredients: Aqua, Herbal Infusion of Aloe Barbadensis Leaf Extract*, Camellia Sinensis (Green tea) Leaf Extract*, Rosmarinus Officinalis (Rosemary) Leaf Extract*, and Robus Ideous (Raspberry) Leaf Extract*, Behentrimonium Methosulfate (Colza Oil), Oenocarpus Bataua (Rahua Ungurahua) Oil, Glyceryl Stearate, Canola Oil, Glycerin, Stearalkonium Chloride (plant derived), Butyrospermum Parkii (Shea) Butter, Saccharum Officinarum (Molasses) Extract, Simmondsia Chinensis (Jojoba) Seed Oil, Bursera Graveolens (Palo Santo) Oil, Potassium Sorbate, Hydrolyzed Quinoa, Tocopherol (Vitamin E), Panthenol * Denotes Organic Ingredient
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User satisfaction is calculated using online reviews and a Bayesian average across all personal care and cosmetic products on Welpr.
Smoothing Hair Treatment - Grown Alchemist
Product Details
- Smoothes hair, eliminates flyaways, and protects against heat damage.
- Fast-absorbing formula leaves hair natural, silky smooth, and hydrated.
- Increases styling manageability and protects hair from chemical, UV, and heat stress.
- Non-toxic, vegan, and cruelty-free with organic botanical ingredients.
- Detangles hair without build-up, leaving it soft, supple, and straightened.
Pros & Cons
Pros
- Repairs and enhances hair softness effectively.
- Leaves hair looking beautiful and styled with ease.
- Highly recommended for hair repair and nourishment.
Cons
- May not suit those sensitive to strong patchouli scent.
Ingredients
Ingredients can vary by product variation and may change at any time by the manufacturer. For the most complete and up-to-date list of ingredients, refer to the product packaging.
To analyze individual ingredients, use INCIDecoder.
Ingredients: Aqua/Water/Eau, Behentrimonium Methosulfate (*Plant), Decyl Oleate (*Plant), Sodium Lactate (*Plant), Lactic Acid (*Plant), Sodium Chloride, Glycerin (*Plant), Levulinic Acid, P-Anisic Acid (*Plant), Cetyl Alcohol (*Plant), Camellia Oleifera Seed Oil, Cetearyl Alcohol (*Plant), Behentrimonium Chloride (*Plant), Starch Hydroxypropyltrimonium Chloride (*Plant), Aloe Barbadensis Leaf Extract, Urea, Leontopodium Alpinum (Edelweiss) Extract (*Plant), Sambucus Nigra (Elderberry) Fruit Extract (*Plant), Panthenol (Pro-Vitamin B5) (*Plant), Cetrimonium Chloride (*Plant), Benzyl Alcohol, Dehydroacetic Acid, Beta Carotene (Provitamin A/Provitamine A), (*Plant), Citrus Clementina (Clementine) Peel Oil, Pogostamon Cablin (Patchouli) Leaf Oil, Polianthes Tuberosa (Tuberose) Flower Oil, Cananga Odorata (Ylang Ylang) Flower Oil, Cedrus Atlantica (Cedarwood) Wood Oil, Benzyl Benzoate (*Plant/Plante), Geraniol (*Plant), Linalool (*Plant), Limonene (*Plant) (*Plant Derived)
Original Brazilian Keratin Hair Treatment - COCOCHOCO
Product Details
- Formaldehyde-free Brazilian keratin treatment infused with cocoa bean extracts
- Promotes healthy hair growth and adds volume
- Repairs very damaged hair while providing lasting softness and shine
- Specially formulated for blonde hair
Pros & Cons
Pros
- Leaves hair smooth and frizz-free, even after air drying.
- Easy to apply at home with clear instructions and video links.
- No formaldehyde or harsh chemicals, making it safer for health-conscious users.
- Has a pleasant chocolatey smell, not overpowering, adding a nice touch during application.
- Helps with hair manageability, especially for those with thick or curly hair.
Cons
- Some users may experience strong fumes; ensure to use in a well-ventilated area.
- Effects might not last very long for everyone, requiring additional applications for lasting results.
Ingredients
Ingredients: Aqua, Cetyl Alcohol, Stearic Acid, Palmitic Acid, Propylene Glycol, Behentrimonium Chloride, Camellia Sinensis Leaf Water, Hamamelis Virginiana (Witch Hazel) Leaf Water, Aloe Barbadensis Leaf Water, Maris Sal, Tocopheryl Acetate, Laurdimonium Hydroxypropyl Hydrolyzed Keratin, Borago Officinalis Seed Oil, Simmondsia Chinensis (Jojoba) Seed Oil, Oenothera Biennis (Evening Primrose) Oil, Hippophae Rhamnoides Oil, Calendula Officinalis Flower Extract, Caprylic/Capric Triglyceride, Butyrospermum Parkii (Shea Butter), Ascorbic Acid, Allantoin, Parfum, Squalane, Retinyl Palmitate, Phenoxyethanol, Isopropyl Alcohol, Benzyl Alcohol, Lactic Acid, Sodium Chloride, Sodium Benzoate, Potassium Sorbate
Common Harmful Chemicals in Hair Straightener & Smoothing Treatment
Chemical Name
Why it’s harmful
Phthalates, linked to endocrine disruption, reproductive toxicity, and cancer, are banned in the European Union but remain prevalent in U.S. cosmetics. They are widely used in personal care products, such as nail polish, fragrances, and eyelash glue and other products. A significant loophole allows phthalates to be added to fragrances without disclosure. Health concerns include endocrine disruption, developmental and reproductive toxicity, and potential carcinogenicity.
Campaign for Safe Cosmetics: Phthalates, Product Profile: Hand Sanitizer, Phthalates in Cosmetics, Phthalates in cosmetic and personal care products: concentrations and possible dermal exposure, A Survey of Phthalates and Parabens in Personal Care Products from the United States and Its Implications for Human Exposure, Phthalates Factsheet, BPA and Phthalates: Chemicals found in our homes
Sodium laureth sulfate, derived from ethoxylated lauryl alcohol, is a surfactant used in sudsy products like toothpaste, detergents, and shampoos. While it acts as a cleansing and emulsifying agent, it can sometimes contain toxic impurities such as 1,4-dioxane. This chemical has raised health concerns due to its potential to cause skin, lung, and eye irritation, organ toxicity, and, primarily because of contamination by 1,4 dioxane, cancer.
The Dirty Dozen: Sodium Laureth Sulfate, 15 Toxic Trespassers, SKIP PRODUCTS MADE WITH SLES (AND SLS, TOO!), Campaign for Safe Costmetics: 1,4-DIOXANE, WHAT IS SODIUM LAURETH SULFATE: CHEMICAL FREE LIVING, A new formula for a mild body cleanser: sodium laureth sulphate supplemented with sodium laureth carboxylate and lauryl glucoside,
Sodium Lauryl Sulfate is recognised as a skin, eye, and respiratory tract irritant according to ICSC. It may cause allergic reactions and eye irritation as stated by the HSDB. Exposure may even result in eye burns, as per CAMEO. Depending on its form - which may range from a solid (90-98% purity), to a paste (30-41%), or an aqueous solution (28-50%) - it can significantly irritate skin and eyes, with adverse effects escalating with increased concentration. Despite these hazards, it is not a skin sensitizer according to CHEMINFO, while eChemPortal: ERMA and MSDSonline endorse its classification as an irritant.
Triclosan is a synthetic pesticide with antibacterial properties commonly added to detergents, soaps, and various personal care products such as deodorants and toothpastes. Although it lacks the ability to combat viruses causing colds and flus, it's used in products like body washes, disinfectants, and some toothpastes to resist bacterial growth. In 2016, the FDA limited its use in antibacterial soaps, but the compound is still permitted in other products. The European Union prohibited its presence in food-contact items in 2010. Exposure to triclosan has been associated with hormone disruption, increased breast cancer risk, liver damage, and the development of resistant super-germs.
Triclosan Exposure, Transformation, and Human Health Effects, Are antibacterial products with triclosan fueling bacterial resistance?, Antimicrobial agents, triclosan, chloroxylenol, methylisothiazolinone and borax, used in cleaning had genotoxic and histopathologic effects on rainbow trout, The Effects of Triclosan on Puberty and Thyroid Hormones in Male Wistar Rats, Triclosan is a potent inhibitor of estradiol and estrone sulfonation in sheep placenta, The in Vitro estrogenic activities of triclosan and triclocarban, Antibacterial Soap? You Can Skip It, Use Plain Soap and Water, Environmental Exposure of Aquatic and Terrestrial Biota to Triclosan and Triclocarban, Triclosan: Environmental Fate and Effects, Chemical Profile: Triclosan / Triclocarban, 5 Things to Know About Triclosan, Underarm Harm? Whats So Bad About Antiperspirants?, Some flame retardants and the antimicrobials triclosan and triclocarban enhance the androgenic activity in vitro, Triclocarban Enhances Testosterone Action: A New Type of Endocrine Disruptor?, Triclosan, a commonly used bactericide found in human milk and in the aquatic environment in Sweden
Benzene is a colorless, sweet-smelling, highly flammable liquid that evaporates quickly into the air and slightly dissolves in water. It's a byproduct of both natural processes and human activities, used extensively in the U.S production of other chemicals for plastics, resins, nylon, rubbers, lubricants, dyes, detergents, drugs, and pesticides. Present in crude oil, gasoline, and cigarette smoke, benzene is also released into the air from burning coal, oil, gasoline stations, and vehicle exhaust. Short-term exposure may cause drowsiness, dizziness, and irritation, while long-term exposure leads to blood disorders, reproductive effects, and even leukemia. Benzene has been classified by EPA as a known human carcinogen, and regulations apply to various industry sectors with potentially high exposure risks.
Triethanolamine appears to cause occupational asthma and allergic contact dermatitis in machinists and photographers, as well as liver and kidney damage in animals with high-dose feeding. It's noted to be an irritant to the skin, eyes, and respiratory tract, with potential to cause skin sensitization, though the rate of skin sensitization in humans is low. Triethanolamine has low acute toxicity, with median oral LD50 values of 4,190-11,260 mg/kg in rats and 5,300-8,000 mg/kg in guinea pigs, and a median dermal LD50 greater than 2,000 mg/kg in rabbits. Triethanolamine is not carcinogenic, developmental toxicant, or toxic to the reproductive system. However, chronic exposure may lead to liver and kidney damage.
Safety assessment of triethanolamine and triethanolamine-containing ingredients as used in cosmetics, Toxicology of mono-, di-, and triethanolamine, Campaign for Safe Cosmetics: Ethanolamine Compounds (MEA, DEA, TEA And Others), The Dirty Dozen: DEA-related ingredients, Chemical Profile, Special Chem, Safety assessment of triethanolamine and triethanolamine-containing ingredients as used in cosmetics
Diethanolamine is a chemical found in various consumer products like shampoos, cosmetics, and pharmaceuticals. Acute exposure in humans can result in irritation of the nose, throat, and skin. However, no detailed data is available on its chronic, reproductive, developmental or carcinogenic effects on humans. Studies on animals reveal that acute oral exposure can influence the liver, blood, kidney, and central nervous system, while dermal exposure has been connected with an increased incidence of liver and kidney tumors in mice. Production of first-degree burns, skin irritation, occupational asthma, kidney, and liver injury risk, and potential skin sensitization are some other adverse effects associated with diethanolamine.
Chemical Safety Facts: Ethanolamines, NTP Toxicology and Carcinogenesis Studies of Diethanolamine, California Environmental Protection Agency: Diethanolamine , International Agency for Research on Cancer: Diethanolamine, Initial List of Hazardous Air Pollutants with Modifications, What is the Toxics Release Inventory?, OPINION CONCERNING DIALKYL- AND DIALKANOLAMINES AND THEIR SALTS IN COSMETIC PRODUCTS, Ethanolamine Compounds (MEA, DEA, TEA And Others), WHAT ARE ETHANOLAMINE COMPOUNDS (DEA, MEA, OR TEA): CHEMICAL FREE LIVING, The Dirty Dozen: DEA-related ingredients, FDA: Diethanolamine, Chemical Profile: Diethanolamine ,
2-Phenoxyethanol is a hazardous substance toxic by all routes of exposure, and is used widely in products like cosmetics, soaps, and inks, among others. The effects of exposure to this faintly aromatic, colorless, oily liquid can include eye irritation, headaches, tremors, and CNS depression. It's crucial to rinse exposed eyes with tepid water for at least 15 minutes and to wash exposed skin thoroughly with soap and water in case of contact. The substance requires preheating before ignition can occur, and if involved in a fire, gentle water spray can extinguish the fire by inducing frothing.
Methylisothiazolinone can reportedly cause allergic contact dermatitis in workers who interact with products containing it. This substance is recognized as a contact allergen for consumers using cosmetics that include it. It can cause skin burns and sensitization, and inhaling it may lead to corrosive injuries in the upper respiratory tract and lungs. Ingesting this substance is harmful, and inhalation is toxic. This preservative is linked to the category of isothiazolinones.
Antimicrobial agents, triclosan, chloroxylenol, methylisothiazolinone and borax, used in cleaning had genotoxic and histopathologic effects on rainbow trout, Methylisothiazolinone toxicity and inhibition of wound healing and regeneration in planaria, Methylchloroisothiazolinone and/or methylisothiazolinone in cosmetic products, Isothiazolinone Biocides: Chemistry, Biological, and Toxicity Profiles, Methylisothiazolinone and isothiazolinone allergy, Analysis of isothiazolinones in environmental waters by gas chromatography–mass spectrometry, Methylisothiazolinone induces apoptotic cell death via matrix metalloproteinase activation in human bronchial epithelial cells, EU REGULATIONS , Methylisothiazolinone contact allergy: a review, Effects of methylisothiazolinone and octylisothiazolinone on development and thyroid endocrine system in zebrafish larvae, Two Cases of Chloromethylisothiazolinone and Methylisothiazolinone-associated Toxic Lung Injury, An update of the risk assessment for methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) with focus on rinse-off products, Effects of a mixture of chloromethylisothiazolinone and methylisothiazolinone on peripheral airway dysfunction in children, Isothiazolinone preservative: cause of a continuing epidemic of cosmetic dermatitis, Campaign for Safe Cosmetics: Methylisothiazolinone and Methylchloroisothiazolinone
Isopropyl alcohol has been shown to cause narcosis in animals during acute studies, as cited by ACGIH. However, according to research by Zimmerman, it is not hepatotoxic in either experimental animal studies or in human exposures. It's known to be a skin, eye, and respiratory tract irritant, and if inhaled in high concentrations, it can cause CNS depression, as indicated by the ICSC.
Octinoxate, commonly found in various cosmetic and personal care products such as hair color products, sunscreen, lipstick, and skin creams, is an endocrine disruptor that mimics estrogen and can affect thyroid function. It has been detected in human urine, blood, and breast milk, indicating systemic exposure. Octinoxate's potential health concerns include its impact on cell proliferation in response to estrogen exposure, disruptions in thyroid hormones, alterations in reproductive systems, and adverse effects on the development of male and female fetuses, as well as their offspring.