Clarifying shampoo: when to use it and how chelating differs

When hair feels coated, heavy, dull or will not hold a style, the cause is often build-up from products, oil or minerals in water. Two kinds of "reset" shampoo are meant for this: clarifying and chelating.

Quick answer: A clarifying shampoo removes product build-up and extra oil. A chelating shampoo is designed to bind minerals, such as those from hard water or pools. Use either only occasionally, often about once or twice a month, always follow with conditioner, and use them less if your hair is dry, curly, bleached or colored. Persistent flakes or itch are not build-up, so see a doctor.

What is build-up?

Build-up is a film that collects on hair and scalp over time. It can include:

• Styling products such as gels, creams, sprays and pomades, and leave-in conditioners.
• Oils and sebum, the natural oil from your scalp, which can build up if you go a long time between washes.
• Dry shampoo residue.
• Minerals from hard water. Hard water contains a lot of dissolved calcium and magnesium. The US Geological Survey explains that soap reacts with calcium to form "soap scum", and that hardness is not a health concern, but it can be a nuisance.

A review of hair cosmetics notes that excess residue is a common issue because so many people use leave-on products, and that some polymers can build up on hair. Residue is not dangerous, but it can make hair look flat, dull or hard to style.

Clarifying vs chelating

Many "hard water" shampoos combine both jobs. If you are not sure, try a clarifying shampoo first, since it is the simpler, better-known option.

Signs your hair may need a reset

• Products that used to work seem to do nothing.
• Hair feels heavy, sticky, waxy or coated.
• Curls lose their shape.
• Hair looks dull, or light hair looks brassy or tinted.
• Your scalp feels coated, or hair gets oily very quickly.

Persistent flakes, itch, redness or burning are different. These are not signs of build-up, and a clarifying shampoo is not a treatment for dandruff.

How to use them

1. Wet hair well.
2. Apply the shampoo to your scalp, not to the whole length. The American Academy of Dermatology (AAD) says shampooing the scalp removes built-up products, dead skin and extra oil while limiting dryness.
3. Massage gently with your fingertips, not your nails, and let the suds run through the lengths as you rinse.
4. Leave it on for the time stated on the label, then rinse thoroughly.
5. Follow with a conditioner or hair mask on the lengths and ends, because these shampoos can leave hair drier.

How often should you use them?

There is no medical rule. The AAD suggests that people who regularly use gels, oils, creams or pomades consider a clarifying shampoo before their moisturizing shampoo. A review of hair cosmetics describes anti-residue shampoos being used about once in every 10 washes, or more often if needed. In practice, many people choose once or twice a month.

• Use more often: if you have an oily scalp, use a lot of product, or swim often. Even then, stay within the label directions.
• Use less often: if your hair is dry, curly, bleached or colored. Stop if your hair feels straw-like or your scalp feels tight or irritated.

Curly, coily and dry hair

Curly hair is drier and more prone to breakage. The AAD advises washing thick, curly hair at least every 2 to 3 weeks, and suggests a clarifying shampoo before a moisturizing one if you use styling products often. For curly hair, always finish with a rich conditioner.

Colored and bleached hair

The hair-cosmetics review notes that heavily highlighted hair is the most sensitive to anti-residue formulas. Strong cleansers can also fade color faster. Ask your colorist how long to wait after coloring, and choose a gentle or color-safe formula. Learn more about color-treated hair.

What not to do

• Do not use one every wash. It is likely to dry your hair.
• Do not use one on a sore, irritated or broken scalp.
• Do not stack several strong cleansers or scrubs in one wash.
• Do not rely on home mixes. There is little good evidence that vinegar or baking soda remove minerals or build-up, and strong mixes can irritate the scalp.
• Do not skip conditioner. It restores softness and makes combing easier.

When to see a dermatologist

• Flakes, itch or redness that continue after clarifying.
• A scalp that burns, stings, oozes or has sores or crusts.
• Increased shedding, a widening part or patches of thinning hair.
• Sudden changes in your hair or scalp that are not explained by products or water.

FAQ

Are clarifying shampoos bad for curly hair?

Not if you use them occasionally and follow with a moisturizing conditioner. Using them too often can dry curls.

Do I need both a clarifying and a chelating shampoo?

Not necessarily. Many people only need a clarifying shampoo. Consider a chelating one if you have hard water or swim often and clarifying does not help.

Will a chelating shampoo remove hair color?

It might fade some color, as many strong cleansers can. Use formulas labeled color-safe and ask your colorist.

Can I use a clarifying shampoo for dandruff?

No. Dandruff is usually treated with a shampoo made for it. The AAD advises applying dandruff shampoo to the scalp only and leaving it on for the time on the label, then using a moisturizing shampoo on the rest of the hair.

Does a clarifying shampoo help hair grow?

No. It cleans hair and scalp, but it is not a treatment for hair loss.

Sources

• 6 curly hair care tips from dermatologists (American Academy of Dermatology)
• Tressed to impress: tips for keeping your mane magnificent (American Academy of Dermatology)
• Hair Cosmetics: An Overview (International Journal of Trichology, 2015; NIH PubMed Central)
• Hardness of water (US Geological Survey)