Hair Smoothening Treatment: Benefits, Cost, Side Effects, and Aftercare

Hair smoothening treatment can soften natural waves, tame frizz and add a glossy finish while keeping some natural bounce, making hair easier to manage without necessarily making it completely straight.

The treatment can also cause dryness, breakage or irritation, so understanding the process, cost, side effects and maintenance helps you make an informed choice.

Reviews and safety updates from the U.S. Food and Drug Administration (FDA) and recent medical literature indicate that chemical and heat-based smoothening can alter the hair shaft, with repeated or improper processing increasing the risk of dryness and breakage.

What Is Hair Smoothening Treatment?

A smoothening hair treatment is a salon process that uses a smoothing or straightening formulation with heat, and sometimes a neutralising step, to reduce frizz and change the appearance or structure of the hair shaft.

The result is usually smoother, more manageable hair, but the effect and risk depend on the exact formula, application method, heat exposure, and condition of the hair and scalp.

How Does Smoothening Change the Hair Shaft?

Hair smoothening works on the hair shaft, particularly its cuticle and internal keratin structure. Depending on the formulation, chemical processing can alter how the hair fibres sit or interact, while heat helps set the smoother shape and finish.

This can make the hair look less frizzy, smoother, and easier to style. However, chemical and heat processing can also increase porosity and weaken the shaft, particularly when hair has already been bleached, coloured, damaged, or repeatedly processed.

Why Is Smoothening Not One Standard Formula?

“Smoothening” refers to a category of salon treatments, not a single, fixed chemical formula. Different services may use thioglycolate or other bond-restructuring systems; keratin-, cysteine-, or carbocysteine-based formulations; or acid-based chemistry.

That matters because the ingredients, processing method, and heat exposure determine both the result and the safety profile. Some products may contain or release formaldehyde-related chemicals when heated, while others do not.

So, rather than judging a treatment by the word “smoothening” alone, it is more useful to ask the salon which product is being used and check its ingredient information or Safety Data Sheet (SDS).

What Are the Benefits of Hair Smoothening?

The main benefits of a smoothening hair treatment are reduced frizz, improved shine, and easier manageability. The exact result depends on the formulation, your hair type, and the condition of the hair before treatment.

Frizz Control, Shine and Manageability

Smoothening can make the hair surface appear more polished, helping reduce the rough, frizzy appearance that makes hair harder to style.

The treated hair may also look shinier and feel easier to manage because the strands sit more smoothly.

The treatment is mainly a cosmetic change to the hair shaft. It does not repair hair at the root or treat the underlying cause of hair fall.

Who Is Most Likely to Like the Result?

People who mainly want less frizz, smoother-looking hair, and easier styling are more likely to appreciate the result.

However, the outcome can vary with hair type, previous chemical processing, humidity, washing habits, and the specific formula used.

If the hair is already severely bleached, highly porous, gummy, or breaking, smoothening may increase the risk of further damage rather than deliver the desired result. A strand assessment is therefore important before treatment.

How Is Hair Smoothening Done?

A smoothening hair treatment usually starts with assessing the hair and scalp, followed by applying a formulation suited to the hair’s condition. The product is then processed and typically heated to create a smoother, more manageable finish.

The exact process varies by treatment, as smoothening can involve different chemical systems. Depending on the formulation, the service may involve bond restructuring, heat sealing or a neutralising step.

That is why the salon should confirm the exact product, processing method, and chemical system before treatment, rather than treating every smoothening service as the same procedure.

What Happens During The Initial Hair And Scalp Assessment?

Before the treatment begins, the stylist should assess the hair strands and scalp condition, including any previous chemical processing and the hair's strength.

A strand test can help determine whether the hair can tolerate the planned formula and heat exposure.

This assessment is particularly important if the hair is bleached, highly porous, already breaking or has recently undergone another chemical treatment.

How Are The Smoothening Product And Heat Applied?

The selected product is applied to the hair and processed according to the specific formulation and the manufacturer's instructions.

Heat, such as blow-drying or flat ironing, is then used as part of the smoothing process to help set the desired finish.

Because different products use different chemistries, there is no single processing time or heat protocol that applies to all hair-smoothening treatments. The exact formula matters more than the salon service name.

When Does A Neutraliser Become Part Of The Process?

A neutraliser is used with certain bond-restructuring formulations, rather than as a universal step in every smoothening service. Its use depends on the chemistry of the product being applied.

That is why asking the salon which formula is being used and whether it requires a neutraliser is more useful than assuming every smoothening treatment follows the same process.

Which Chemicals Are Used In Hair Smoothening?

There is no single chemical formula for a smoothening hair treatment. Salon products can use different systems, so the ingredient list and processing method matter more than the treatment name.

How Do Thioglycolates Restructure The Hair?

Thioglycolate-based systems, including ammonium thioglycolate, work by altering the hair’s disulfide bonds. They are used in chemical bond-restructuring treatments and may require a neutralising step.

How Do Keratin, Cysteine, and Acid-Based Formulas Work?

Other smoothening products use keratin-based, cysteine/carbocysteine, or acid-based formulations. Their chemistry and heat requirements vary, so the exact product should be checked rather than assuming all treatments work the same way.

Why Are Formaldehyde, Formalin, and Methylene Glycol Important?

Some hair-smoothing products can release formaldehyde gas when heated. Exposure may irritate the eyes, skin, and airways, and formaldehyde is a known human carcinogen. Before treatment, ask for:

• The exact ingredient list
• The product Safety Data Sheet (SDS)
• Adequate salon ventilation

Is “Formaldehyde-Free” Enough To Guarantee Safety?

Not necessarily. The FDA recommends checking specifically for formaldehyde, formalin, and methylene glycol, rather than relying only on marketing claims.

Some glyoxylic/glycolic acid formulations have also raised an emerging safety concern, as case reports and reviews have described acute kidney injury after exposure to certain hair-straightening products. This does not apply to every smoothening treatment.

What Are The Side Effects Of Hair Smoothening?

A smoothening hair treatment can affect both the hair shaft and scalp, particularly when the process is repeated or performed incorrectly. The risk depends on the formula, processing, and heat used.

Can Smoothening Make Hair Dry And Brittle?

Chemical processing can weaken the hair shaft, leading to:

• Dryness and increased brittleness
• Breakage and split ends
• Changes in hair strength and texture

Repeated or improper processing can increase the risk of shaft damage.

Can Smoothening Irritate Or Burn The Scalp?

Yes. Chemical exposure can cause scalp irritation, inflammation, eczema or chemical burns. Allergic reactions are also possible with some formulations.

Can Smoothening Fumes Irritate the Eyes and Airways?

Some heated smoothening products can release formaldehyde gas, which may irritate the eyes, nose, lungs and skin. This is why proper ventilation and checking the product’s ingredient list or SDS matter.

What Should You Know About Glyoxylic Acid?

Some hair-straightening products containing or suspected of containing, glyoxylic/glycolic acid have been linked to acute kidney injury in case reports and reviews. This is an emerging concern for specific formulations, not a risk that applies to every smoothening treatment.

Does Hair Smoothening Cause Permanent Hair Loss?

Usually, no. A smoothening hair treatment more commonly causes hair-shaft breakage or temporary shedding rather than permanent hair loss.

Permanent loss becomes a concern if severe scalp injury causes follicular damage or scarring, which is not the routine outcome.

How Can You Tell Breakage From Shedding?

Hair breakage and hair shedding can look similar after smoothening, but the pattern of hair loss can help you tell them apart:

• Breakage: Many short, uneven strands with rough or broken ends; the hair snaps along the shaft.
• Shedding: Full-length strands come out from the root and may have a root bulb.
• Follicular loss: Persistent, patchy, or progressive thinning may indicate an underlying hair-loss condition.

When Does Hair Fall Need A Dermatologist?

Hair loss after smoothening needs a dermatologist’s assessment when it shows any of these patterns:

• Patchy or progressively worsening
• Lasting for more than 6 to 8 weeks
• Associated with scalp pain, burning, scaling or scarring
• Causing severe breakage that continues after stopping chemical processing

Note: A smoothening treatment changes the appearance and behaviour of the hair shaft; it does not treat medical causes of hair loss.

How Much Does Hair Smoothening Cost In India?

The hair-smoothing cost in India usually ranges from ₹3,000 to ₹12,000 or more, while Mumbai salon prices often range from ₹ 4,000 to ₹6,000. The final price depends on the hair length, thickness, product formula, and salon.

What Is The Typical Price Range?

Hair smoothening prices in India typically fall within the following range:

• India: ₹3,000 to ₹12,000+
• Mumbai: Around ₹4,000 to ₹6,000 starting prices

These are indicative ranges and can vary between salons and formulations.

What Changes The Final Cost?

Several factors can affect the final hair smoothening cost, including:

• Longer or thicker hair
• Premium or specialised formulations
• Salon pricing and location
• The amount of product and processing required

How Long Does Hair Smoothening Last?

Hair smoothening results commonly last around 3 to 6 months, but the duration varies with the formulation, hair type, washing habits, humidity, and new hair growth.

How Long Do Smoothening Results Usually Last?

Semi-permanent smoothening gradually wears off with washing and new growth. The exact duration depends on the product chemistry and how the hair is maintained, so there is no fixed timeline for everyone.

What Happens As New Hair Grows?

Smoothening changes the treated hair shaft, not the hair follicle. As new hair grows, it develops with its natural texture, so the difference between treated lengths and new growth can become noticeable.

What Aftercare Does Hair Smoothening Need?

Hair smoothening aftercare should focus on following the instructions for the exact formulation, while limiting unnecessary heat and chemical processing.

There is no universal aftercare routine, as washing and styling instructions vary by product.

When Can You Wash Your Hair?

Follow the manufacturer's or salon instructions for the product used. Some formulations require a waiting period before washing, while others do not, so a fixed 48 or 72 hour rule should not be applied to every treatment.

How Should You Care For Smoothened Hair?

Keep the routine gentle and follow the product-specific aftercare guidance. If the hair feels dry, prioritise gentle conditioning and avoid unnecessary heat or repeated chemical processing, which can worsen existing damage.

Can You Oil Or Tie Your Hair?

Oiling is optional, and the right timing depends on the product used. Tight hairstyles may also be discouraged initially, as some formulations can cause the hair to crease.

Kibo Clinics' Perspective On Smoothening Hair Treatment?

Choosing a smoothening hair treatment should depend on your hair condition, scalp health, and the exact formula being used. While it can improve smoothness and manageability, it does not treat underlying hair loss or thinning.

At Kibo Clinics, we recommend assessing your hair and scalp first, especially if you have persistent shedding, breakage or thinning, rather than relying on a cosmetic treatment alone.

If you're unsure whether hair smoothening is right for you, a Kibo Clinics board-certified hair transplant surgeon can assess your hair and scalp, identify potential causes of hair loss, and recommend a personalised treatment plan.

Frequently Asked Questions