Redken's newest launch, Acidic Grow Full System, is built around a fairly simple pitch: fuller, thicker-looking hair from the first use, without a single extension or texturising trick involved. It's designed specifically for thin, flat or fine hair, and rather than working from the strand down, it starts at the scalp, which is a meaningfully different approach from most volumising haircare.
What Makes This Different From a Regular Volumising Shampoo?
Most "volumising" haircare works on the hair shaft itself, coating strands to make them feel thicker or adding texture so hair holds a style with more lift. Acidic Grow Full System takes a different starting point: the scalp. The system is built around a 7% Densifying Complex combining azelaic acid, caffeine and prebiotics, three ingredients that work together rather than in isolation. Azelaic acid helps rebalance the scalp's natural acid mantle, caffeine is included to energise the scalp environment, and prebiotics support the scalp's microbiome, the balance of good bacteria that keeps skin, and scalp, functioning properly.
That scalp-first approach fits into Redken's broader shift toward pH-balanced, "acidic" haircare over the last few years, the same underlying philosophy behind the brand's Acidic Bonding Concentrate range for damaged hair. The idea across both is that healthy hair starts with getting the hair and scalp's natural pH right, rather than just adding a coating ingredient on top.
Who Is This System Actually For?
Redken positions Acidic Grow Full specifically for thin, flat or fine hair, particularly anyone noticing hair fall from breakage during brushing or hair that looks limp by the end of the day regardless of how it's styled. It isn't marketed as a medical hair loss treatment, and Redken is specific about the claim: the system is built to hydrate the scalp, reduce breakage from brushing, and deliver instantly fuller, thicker-looking hair using the complete system together, the equivalent of the visual fullness of more than 5,000 additional hair fibres from first use.
What's Actually in the System?
Densifying Shampoo: The cleansing step, formulated to gently wash the scalp and hair while delivering the Densifying Complex, rather than a heavy-duty clarifying shampoo that could work against the hydration goal.
Densifying Conditioner: A lightweight conditioner designed to detangle and soften without weighing down already-fine hair, keeping the fullness the shampoo and complex are working toward rather than flattening it back out.
Scalp & Hair Serum: A leave-in, fast-absorbing serum applied directly to the scalp, the step doing most of the direct work of hydrating the scalp environment and reinforcing hair against breakage from daily brushing.
Instant Densifying Spray: The finishing step, an in-the-moment root-lifting spray built to add instant, visible fullness at the root on styled or dry hair, the part of the system closest to a traditional volumising product.
Expert Tip: Hairhouse stylists recommend applying the Scalp & Hair Serum directly to towel-dried scalp rather than through the lengths, since the ingredients doing the actual work, the azelaic acid, caffeine and prebiotic blend, are formulated to act where fullness actually starts. Save the Instant Densifying Spray for root application on dry or styled hair as a top-up between washes.
Is This Worth Switching to If You Already Have a Volumising Routine?
If your current routine is a standard volumising shampoo and conditioner and your hair is simply fine or flat without much breakage, you may not need to overhaul anything. Where Acidic Grow Full earns its place is for hair that's both thin-looking and shedding more than expected from brushing or general handling, since it's addressing scalp condition and breakage alongside the cosmetic fullness most volumising products focus on alone. Using the full four-step system together is where Redken's own testing shows the strongest result, rather than picking off a single product from the range.
Frequently Asked Questions
What does Redken's Acidic Grow Full System actually do?
It's built around a 7% Densifying Complex of azelaic acid, caffeine and prebiotics that works on the scalp to hydrate it, support the scalp microbiome, and reduce breakage from brushing, delivering the visual appearance of instantly fuller, thicker hair.
Who is Acidic Grow Full System designed for?
Thin, flat or fine hair, particularly anyone noticing breakage from brushing or hair that looks limp rather than full, regardless of how it's styled.
Is Acidic Grow Full a hair loss treatment?
No. It's a cosmetic haircare system designed to improve the appearance of fullness and support scalp condition, not a medical or clinical hair loss treatment.
Do I need to use all four products together?
Redken's testing is based on using the full system, shampoo, conditioner, scalp and hair serum, and the instant densifying spray, together for the strongest result, though each step still offers a standalone benefit.
How is this different from Redken's Acidic Bonding Concentrate range?
Acidic Bonding Concentrate is built for damaged, over-processed hair and bond repair. Acidic Grow Full shares the same pH-balanced "acidic" haircare philosophy but is specifically formulated for thin, flat hair and scalp-driven fullness rather than damage repair.
Redken's Acidic Grow Full System has just landed at Hairhouse, with the Densifying Shampoo, Densifying Conditioner, Scalp & Hair Serum and Instant Densifying Spray all part of the new range. Check the Redken collection at Hairhouse for the latest stock, and a Hairhouse stylist can help you work out whether the full system or just a couple of steps suit your hair.