NIOXIN Scalp & Hair Thickening Treatment 6.8 fl oz for Color-Treated Hair — Lightweight Leave-In Serum

NIOXIN System 4 Scalp + Hair Thickening Treatment is a lightweight leave-in serum formulated to strengthen and visually thicken color-treated hair with progressed thinning while nourishing the scalp.

This professional-grade leave-in treatment is the finishing step in NIOXIN’s three-part System 4 regimen designed specifically for colored, chemically treated hair that shows signs of progressive thinning. The formula delivers antioxidants, botanicals and UV-protecting ingredients to the scalp and hair shaft to help reduce breakage, improve manageability and create a healthier environment for fuller-looking hair appearance.

How does this treatment support thinning, color-treated hair?

The serum targets fragile, chemically stressed strands and the scalp environment to help increase hair diameter and reduce visible thinning. It doesn't alter hair color and works alongside the System 4 cleanser and conditioner to amplify hair structure and resilience.

• Delivers nutrients and antioxidants to the scalp and hair fiber
• Contains UV-protection to help shield color-treated hair
• Designed to increase hair diameter for a fuller visual effect
• Formulated for use as the leave-in final step of System 4

When and how should I apply the NIOXIN Scalp + Hair Thickening Treatment?

Use the treatment on damp hair after shampooing and conditioning with the matching System 4 products. Apply evenly at the scalp and through lengths, then style as usual; it's a leave-in product so rinsing is not required.

• Apply daily or as directed after System 4 Cleanser and Scalp Therapy Conditioner
• Distribute from roots to mid-lengths for even coverage
• Leave in—no rinsing—to maintain hair diameter benefits throughout the day
• Works well under styling products and provides a lightweight finish

What visible results can I expect and in what timeframe?

Visible improvements in fullness and hair diameter are often noticed with consistent use; many users report enhanced thickness and density within weeks when the full three-step system is used. Results vary by individual and depend on consistent regimen use and hair condition.

• Designed to increase hair thickness and fullness with regular use
• Helps minimize breakage that contributes to thinning appearance
• Supports scalp health by clearing impurities and excess sebum
• Compatible with color-treated hair and helps protect color from environmental stress

Is this treatment safe for chemically treated or sensitive scalps?

The formula is created for colored and chemically processed hair and aims to refresh and protect the scalp without altering hair color. If you have a sensitive scalp or specific allergies, patch testing or consulting a professional stylist is recommended before regular use.

• Specifically formulated for color-treated, damaged hair with progressed thinning
• Contains botanicals and antioxidants to nourish the scalp
• Developed by a brand experienced in thinning-hair solutions
• Patch test if you have known sensitivities or allergies

Who this is for: NIOXIN System 4 Scalp + Hair Thickening Treatment is intended for people with color-treated or chemically processed hair experiencing progressed thinning who want a lightweight, salon-quality leave-in serum to strengthen strands, protect color, and improve the look of density. It pairs with the System 4 Cleanser and Scalp Therapy Conditioner as part of a targeted three-step regimen for scalp health and fuller-looking hair.

Ingredients

Aqua, Phenylbenzimidazole Sulfonic Acid, Niacinamide, Benzophenone-4, Caffeine, Polysorbate 20, Sodium Hydroxide, Benzyl Alcohol, Sodium Benzoate, Phenoxyethanol, PEG-12 Dimethicone, Citric Acid, Cocamidopropyl Betaine, Acetamide MEA, Isopropyl C12-15-Pareth-9 Carboxylate, Tetrasodium EDTA, Propylene Glycol, Methyl Nicotinate, Sodium Chloride, Parfum, Polysorbate 60, Polysorbate 80, Mentha Piperita Oil, Mentha Arvensis Leaf Oil, Menthol, PEG-23M, Camellia Sinensis Leaf Extract, Limonene, Cystine Bis-PG-Propyl Silanetriol, Biotin, Lecithin, Tocopheryl Acetate, Foeniculum Vulgare Fruit Extract, Silica, Faex Extract, Acer Saccharum Extract, Citrus Limon Peel Extract, Saccharum Officinarum Extract, Vaccinium Myrtillus Leaf Extract, Citrus Aurantium Dulcis Fruit Extract, Potassium Sorbate