A leave-in conditioner is a light conditioner you apply to towel-dried hair and don't rinse out, while a deep conditioner or hair mask is a richer treatment you leave on for several minutes and then rinse away. Dermatologists say many people benefit from using both a rinse-off conditioner and a leave-in.
Below, we compare rinse-out, leave-in, deep conditioner and hair masks, explain how conditioners work, and show how to choose and apply each for your hair type, plus pre-poo treatments.
Key takeaways
- Rinse-out conditioner is the everyday step; dermatologists suggest using it after every wash.
- Leave-in conditioner goes on damp hair, mid-lengths to ends, and stays in.
- Deep conditioners and masks are thicker, more concentrated rinse-out treatments.
- Don't use a rinse-out conditioner as a leave-in, the AAD advises.
- Fine hair needs lighter formulas; curly and dry hair usually needs more.
Leave-in conditioner vs. deep conditioner vs. hair mask: the differences
All four products condition hair. They differ in texture, concentration and whether they stay on.
| Product | When you use it | Rinse out? | Best for |
|---|---|---|---|
| Rinse-out conditioner | After every shampoo | Yes | Everyone; the everyday basic |
| Leave-in conditioner | On towel-dried hair after washing | No | Frizz, tangles, long, curly, heat-styled or treated hair |
| Deep conditioner | In place of regular conditioner, periodically | Yes, after a longer wait | Dry, damaged or frequently styled hair |
| Hair mask | In place of regular conditioner, periodically | Yes | Similar to deep conditioner; the terms overlap |
| Pre-poo | Before shampooing | Yes, with your shampoo | Detangling and protecting lengths before washing |
"Deep conditioner" and "hair mask" are often used interchangeably. A 2015 review of hair cosmetics in the International Journal of Trichology describes deep conditioners as containing more concentrated ingredients or simply more viscosity than a regular conditioner.
How conditioners work
Hair fibers carry a negative surface charge. According to the same review, conditioners use positively charged (cationic) ingredients that neutralize that charge, which reduces static, frizz and friction between strands. Fatty alcohols such as cetyl and stearyl alcohol, silicones such as dimethicone, and oils lubricate the surface and make combing easier. Film-forming silicones and oils can also help smooth the cuticle and add shine.
The review also notes that damage builds up from root to tip, so the ends are the oldest and most worn part of each strand. That's why most conditioning advice focuses on the mid-lengths and ends, and why bleached or chemically treated hair tends to take up more conditioning ingredients.
What leave-in conditioner does
The American Academy of Dermatology (AAD) says the benefits of a leave-in are immediate: less frizz, easier combing and less breakage from tugging. Dermatologists quoted there say rinse-off conditioner alone may not be enough for long, fine, color-treated, permed or heat-styled hair.
The AAD lists hair types that may benefit from a leave-in:
- Color-treated or permed hair
- Hair styled with blow dryers, curling irons or straighteners
- Long hair
- Curly hair
- Dry, brittle, tangled, frizzy or flyaway hair
- Fine, limp hair, with a lightweight formula
Two practical points from the same page: you can use a leave-in after every shampoo, and if it is applied from mid-strands to ends rather than on the scalp, it is fine to leave in for up to a week before washing it out. The AAD also warns against using a rinse-off conditioner as a leave-in, because rinse-off formulas can contain detergent that may damage hair when left on.
Leave-ins also help outside the bathroom. Cleveland Clinic dermatologist Taylor Bullock, MD, suggests applying a leave-in conditioner or hair oil before swimming to create a protective layer against chlorinated water.
Deep conditioner and hair masks for dry hair
A deep conditioner or hair mask is the step to add when everyday conditioner isn't enough. The 2015 review recommends thick, moisturizing masks with ingredients such as hydrolyzed amino acids, silicones and plant oils, particularly after a stronger anti-residue (clarifying) wash. If you clarify, our clarifying shampoo guide covers how to pair the two.
How often depends on your hair. Dermatologist guidance we found gives a few reference points:
- For frequent swimmers, Cleveland Clinic suggests deep conditioning once a week.
- The AAD's tips for Black hair suggest a hot oil treatment twice a month for moisture and elasticity, alongside conditioner every wash.
- The AAD's list of habits that damage hair recommends that swimmers use a swimmer's shampoo and a deep conditioner after rinsing.
Beyond that, follow your product's directions, and use masks less often if hair turns limp or greasy.
Pre-poo: conditioning before you shampoo
A pre-poo is a conditioner, oil or treatment applied to dry or damp hair before shampooing. The idea is to give the lengths slip for detangling and some protection from the wash itself.
The best-known research is a 2003 lab study in the Journal of Cosmetic Science, which compared coconut, sunflower and mineral oils on hair samples. Coconut oil was the only one that markedly reduced protein loss, in both undamaged and damaged hair, when used as a pre-wash and post-wash product. The authors credit coconut oil's small, straight-chain structure for letting it penetrate the hair shaft. The study was done on hair fibers, not people, and the authors worked for a company that makes coconut oil products. The 2015 review adds that oils can reduce how much water hair absorbs, which may limit the repeated swelling and drying that wears hair down.
How to choose by hair type
Fine or straight hair
The AAD's healthy hair tips say fine or straight hair needs conditioner only on the ends. Choose a light rinse-out conditioner and, if you want a leave-in, a spray or lightweight lotion. Use masks sparingly so hair doesn't fall flat.
Curly or coily hair
Curly hair needs more conditioning, according to the AAD, and the 2015 review notes that natural oils travel poorly down a curl, so the fibers tend to be dry and prone to breakage. Condition the full length every wash, add a creamy leave-in, and consider a regular deep conditioner or pre-poo for detangling. The AAD suggests combing curly hair while damp, with a wide-tooth comb, and notes that thick, curly hair can be combed in the shower before you rinse out conditioner.
Dry or damaged hair
Dry or curly hair needs conditioner along its entire length, the AAD says. Pair a rinse-out conditioner with a leave-in and a periodic mask, and look at the habits behind the dryness: the AAD recommends lower heat, less frequent hot tools and blotting rather than rubbing hair with a towel.
Color-treated hair
Colored, bleached and permed hair is on the AAD's list of hair types that may benefit from a leave-in. The AAD also advises conditioning after every wash and spacing chemical services apart, and mentions a leave-in conditioner with zinc oxide as one way to protect hair from the sun.
How to use each type of conditioner
- Pre-poo (optional): work it through dry or damp lengths, detangle gently, wait as directed, then shampoo.
- Shampoo the scalp. The AAD advises massaging shampoo into the scalp and letting it rinse through the lengths.
- Rinse-out conditioner or mask: apply from mid-lengths to ends (full length if curly or dry). For a deep conditioner or mask, leave it on for the time on the label, then rinse.
- Blot, don't rub. Wrap hair in a towel or T-shirt to absorb water.
- Leave-in: on slightly damp hair, use the smallest amount that works, applied to the hair only, not the scalp. Rub a cream between your palms first, or spray from mid-strands to ends.
- Detangle with a wide-tooth comb, starting at the ends and working up.
- Style as usual, adding a heat protectant if you use hot tools.
What to look for when buying
- The right texture for your hair. Sprays and light lotions for fine hair; creams, butters and masks for curly, coily or dry hair.
- Clear directions. Make sure the label says leave-in or rinse-out, and follow it.
- Your scalp's needs. Keep rich products off the scalp to avoid buildup and irritation.
- Fragrance, if you react easily. Patch-test first.
Shop our conditioners and hair masks and hair styling collections. From the listings:
- Banana Leave-In Conditioner is a creamy leave-in with banana extract and marshmallow root, described as moisturizing without feeling heavy.
- Coconut Milk Strengthening Deep Conditioner is a rich rinse-out treatment made for hair that feels weak or dry from heat, color, protective styles or everyday handling.
- Fenugreek Detangling Pre-Poo goes on before shampoo and is designed to add slip, loosen tangles and release shed hair.
Curious about oils as a pre-poo? Our guide to castor oil for hair looks at what's known about it.
Who should be careful
- Anyone with a sensitive scalp. The AAD advises keeping leave-in off the scalp to avoid buildup and irritation. Patch-test new products on your inner arm for 7 to 10 days, as the AAD describes.
- Fine hair prone to limpness. Heavy masks and butters can weigh it down.
- Persistent breakage. The AAD recommends seeing a board-certified dermatologist if breakage or unmanageable hair continues despite using both a rinse-off and a leave-in conditioner.
FAQ
Can you use leave-in conditioner every day?
Yes, for many people. The AAD says you can apply leave-in after every shampoo, especially on long or chemically treated hair, and that it can stay in for up to a week if applied from mid-strands to ends rather than the scalp. Use the smallest amount that works, and wash it out with shampoo if hair starts to feel coated.
Do I need a leave-in if I already use conditioner?
Not always. Dermatologists quoted by the AAD say rinse-off conditioner alone may not be enough for long, fine, color-treated, permed or heat-styled hair, and that many people benefit from both. If your hair combs easily and isn't frizzy after regular conditioner, a leave-in is optional.
Is a hair mask the same as a deep conditioner?
Mostly. Both are rinse-out treatments that stay on longer than a regular conditioner, and brands use the names interchangeably. A 2015 review describes deep conditioners as having more concentrated ingredients or more viscosity. Follow each product's directions for how long to leave it on and how often to use it.
How often should you deep condition your hair?
It depends on your hair. Cleveland Clinic suggests weekly deep conditioning for frequent swimmers, and the AAD suggests a hot oil treatment twice a month for Black hair. Dry, curly or damaged hair may benefit from regular masks, while fine hair may need them only occasionally. Cut back if hair feels heavy or greasy.
Can I use regular conditioner as a leave-in?
The AAD advises against it. Rinse-off conditioners can contain detergent that may damage hair if left on, and the common tip of diluting conditioner in a spray bottle can do more harm than good. Choose a product labeled as a leave-in conditioner for your hair type instead.
Should you use leave-in conditioner before or after a hair mask?
After. A hair mask or deep conditioner goes on in the shower and is rinsed out. Once you've towel-dried your hair, apply a small amount of leave-in to slightly damp hair, then detangle and style. That order follows the AAD's routine: shampoo, rinse-off conditioner, towel-dry, then leave-in.
Sources
- American Academy of Dermatology: Dermatologists' top tips for using leave-in conditioner
- American Academy of Dermatology: Tips for healthy hair
- American Academy of Dermatology: 10 hair care habits that can damage your hair
- American Academy of Dermatology: Black hair: Tips for everyday care
- American Academy of Dermatology: How to test skin care products
- Gavazzoni Dias MFR. Hair Cosmetics: An Overview. International Journal of Trichology, 2015
- Rele AS, Mohile RB. Effect of mineral oil, sunflower oil, and coconut oil on prevention of hair damage. Journal of Cosmetic Science, 2003
- Cleveland Clinic: How to Protect Your Hair From Chlorine
This guide is general information, not medical advice. Patch-test new products and ask a dermatologist or doctor about skin or health concerns.
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