Thinking about pairing Olaplex No.4 and No.5 for smoother, stronger hair? Here is what to expect, who it works for, and the best way to use this bond-building duo.
Overview
Olaplex No.4 Bond Maintenance Shampoo and No.5 Bond Maintenance Conditioner are designed as a pair to help reduce breakage, smooth frizz, and make damaged hair look and feel healthier over time. The line’s signature is a patented bond-building molecule, Bis-Aminopropyl Diglycol Dimaleate. In simple terms, it helps re-link broken disulfide bonds inside the hair fiber caused by coloring, bleaching, heat styling, and everyday wear and tear. The shampoo focuses on gentle cleansing that will not strip color, and the conditioner aims to restore softness, slip, and shine while supporting that bond-building process.
Both formulas are concentrated, so the bottles look small compared with many salon products, but the amount needed per wash is modest. No.4 uses a blend of sulfate-free surfactants that lather well without feeling harsh. No.5 is a creamy, cushiony conditioner with rich fatty alcohols and conditioning agents that improve detangling and reduce snagging. Together, they target the two biggest challenges with damaged hair: keeping the cuticle smooth and the internal structure supported.
Expect an immediate cosmetic improvement in softness and frizz reduction after the first use, with more meaningful changes in breakage and elasticity appearing after several washes. They are color-safe and pH-balanced, which matters if you are maintaining a salon color or balayage. There is a light, clean salon fragrance that fades after drying. The main trade-offs are cost, the potential for the conditioner to feel heavy on very fine hair, and the need to alternate with a clarifying wash if you are prone to buildup.
Who it’s for
This duo suits people with light to moderate damage who want smoother, easier-to-detangle hair without sacrificing color vibrancy. If you highlight, bleach, perm, or heat style regularly, No.4 and No.5 can help limit ongoing breakage and keep hair feeling supple between treatments. Wavy, curly, and coily textures that need moisture and slip will appreciate the conditioner’s plush feel, especially on porous mids and ends.
If your hair is extremely fine, easily weighed down, or you struggle with an oily scalp, the conditioner may feel rich. That does not mean you cannot use it, but you will likely want to use a smaller amount, keep application away from the roots, and rinse thoroughly. People who love a squeaky-clean scalp may find the shampoo too gentle on days with heavy product, oils, or dry shampoo. In that case, plan to incorporate a clarifying shampoo once a week or as needed.
The pair is a safe choice for color-treated hair and keratin treatments. If you wear extensions, apply the conditioner from mids to ends and keep it off the bonds to avoid loosening adhesives. Those who are fragrance-sensitive should note the scent, although it is not heavy and dissipates quickly.
How it feels and performs
Shampoo texture and cleanse: No.4 is a thick, pearly gel that feels concentrated from the first squeeze. It spreads best when emulsified in your palms and then on very wet hair. The first lather is creamy with a medium density that ramps up as you add water. On a typical wash day with light styling products, one wash is enough and the hair rinses clean without squeak. On days with oils or dry shampoo, a quick first cleanse followed by a second, smaller pass creates a fuller lather and a fresher-feeling scalp. The shampoo does not leave hair rough or tangly, which helps preserve fragile ends during the wash process.
Conditioner slip and softness: No.5 is a rich cream with high slip, so the comb glides more easily even on knotty or highlighted hair. It immediately softens the cuticle, making it far easier to detangle in the shower. After rinsing, hair feels plush and pliable rather than coated or sticky. On coarse or curly textures, there is a satisfying weight that tamps down frizz. On fine hair, that same richness can read as a little heavy on day two if too much product is used or if it reaches the roots. A pea to nickel-size amount for shoulder-length fine hair is usually plenty. For dense or highly porous hair, a quarter-size to half-dollar amount makes more sense.
Dry-down and next day feel: Post-blow-dry, the pair leaves a smoother surface with a more reflective shine than a basic moisturizing duo, and brushing often feels more effortless with fewer snags. Breakage and split ends do not disappear overnight, but with repeated use the hair tends to feel a bit more elastic and less brittle, especially at the ends. In humid weather, frizz is better controlled, though not eliminated if your cuticle is very lifted. On day two, fine hair may feel a touch softer at the root than ideal if conditioner touched the scalp, so placement and thorough rinsing matter. Thicker hair types usually enjoy the lingering softness.
Long-term effects and buildup: Over several weeks, the pair can reduce the amount of breakage you see in your brush or shower drain simply by making detangling easier and supporting the hair’s internal bonds. Because the formulas are rich and protective, some users notice dullness or a heavy feeling if they never clarify. If that happens, add a clarifying shampoo once every 1 to 2 weeks, or swap in a lighter daily conditioner midweek. After a reset, the bounce and shine return without losing the smoothing benefits.
Scalp comfort: The shampoo’s gentle surfactants are friendly to most scalps. If you are very sensitive, the light fragrance may be noticeable during the wash but does not linger. Those who prefer a stronger cooling or exfoliating wash will not find it here, since No.4 emphasizes softness and color safety over a deep scrub sensation.
How to use for best results
Amount and emulsify: Start with a quarter-size amount of No.4 for shoulder-length hair. Emulsify in your palms first, then apply to very wet hair. Add water as you massage for more lather rather than adding more product. Rinse thoroughly. If you used heavy stylers or dry shampoo, repeat with a dime-size second cleanse.
Condition strategically: Squeeze out excess water so the conditioner can grip the hair. Apply No.5 from mids to ends, comb through with your fingers or a wide-tooth comb, and leave it on for 3 minutes. For coarse, highly porous, or very dry hair, 5 minutes is helpful. For fine hair, use a smaller amount, focus below the ears, and avoid the roots. Rinse well until the hair feels silky but not slick.
Frequency and rotation: Most people do well using this pair two to three times per week. If your scalp runs oily or you use heavy stylers, alternate with a clarifying shampoo every one to two weeks. If you feel the conditioner is too rich every wash, rotate in a lighter conditioner midweek while keeping No.5 for days when you heat style or color.
Enhance the results: Gently blot with a microfiber towel instead of rough rubbing, detangle from the ends up, and use heat protectant before blow-drying or ironing. On compromised hair, pre-shampoo treatments and occasional deep conditioning can amplify softness and reduce breakage. If you are extending time between color services, consistent use of No.4 and No.5 supports maintenance by keeping hair supple and easier to manage.
Pros and cons
- Pros: Noticeably smoother, softer hair after the first wash; helps reduce frizz and improve shine; bond-building support that can lessen breakage over time; rich lather without harsh sulfates; excellent slip for detangling; concentrated formulas mean fewer pumps per wash; color-safe and pH-balanced.
- Cons: Premium price per ounce; conditioner can weigh down very fine or low-density hair if overapplied or applied at the roots; shampoo is not clarifying and may require an occasional reset for buildup-prone scalps; light fragrance may not suit the very fragrance-sensitive; results plateau on severely compromised hair that may need more intensive treatments or trims.
Final verdict
Olaplex No.4 and No.5 deliver what many damaged hair routines are missing: a gentler cleanse that does not rough up the cuticle and a conditioner that restores slip so hair breaks less during detangling and styling. Add the brand’s bond-building chemistry and you have a duo that can keep colored and heat-styled hair looking smoother and feeling stronger with steady use. If you are seeking a deep, squeaky cleanse or you have ultra-fine hair that gets flat from richer conditioners, you may need to tweak the amount, adjust how you apply, or rotate in a clarifying or lighter option. For everyone else, especially those with color-treated, highlighted, or naturally coarse textures, No.4 and No.5 are a reliable, concentrated pair that earns its keep by making hair feel more manageable day after day.
See also
If you’re comparing Olaplex with other options for stressed strands, explore our guide to the best conditioner for damaged hair and see how the Moroccanoil Moisture Repair Shampoo and Conditioner duo stacks up.
- For a complementary bond-repair leave-in, take a look at our Redken Acidic Bonding Concentrate Leave-In review.
- If you love efficient beauty routines, you may also appreciate the time-saving power outlined in our Vitamix A3300 blender review.
- To upgrade your at-home pampering days with café-quality drinks, consider the machine featured in our Jura E4 coffee machine review.
FAQ
Are Olaplex No.4 and No.5 safe for color-treated or highlighted hair?
Yes. Both formulas are color-safe and pH-balanced, so they cleanse and condition without stripping dye or dulling toner prematurely. The shampoo’s gentle surfactants avoid the harshness of classic sulfates, and the conditioner helps smooth the cuticle, which keeps color looking reflective.
Will No.5 weigh down fine or low-density hair?
It can feel rich if overapplied. Use a pea to nickel-size amount for shoulder-length fine hair, concentrate from mids to ends, and avoid the roots. Rinse thoroughly. If you still want more lift, alternate No.5 with a lighter conditioner midweek or save No.5 for heat-styling days when extra smoothing helps.
How often should I use Olaplex No.4 and No.5 for best results?
Two to three wash days per week works for most people. If you use heavy styling products or dry shampoo, do a quick double cleanse on those days or incorporate a clarifying shampoo every one to two weeks. Consistency matters more than sheer volume; steady use is what improves softness and helps reduce breakage over time.
Can I use these with keratin treatments or hair extensions?
Yes. The duo is gentle and compatible with keratin-treated hair. If you have tape-in or bonded extensions, keep conditioner away from the bonds and apply it from mids to ends only. As with any extensions, thorough rinsing and careful detangling help preserve attachment points.
Do these products actually repair hair or just make it feel softer?
You get both immediate cosmetic smoothing and internal support. The conditioner provides slip and surface smoothing right away. The bond-building molecule supports internal bonds with repeated use, which helps hair feel stronger and less brittle. Severely compromised hair will still need trims and may benefit from additional targeted treatments, but the duo can meaningfully improve manageability and reduce ongoing breakage.
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