Hair Relaxers vs. Hair Straightening Treatments: What’s the Difference and Why It Matters
As conversations around cosmetic safety continue to evolve, there has been growing confusion around the difference between hair relaxers and hair straightening or smoothing treatments.
These products are often discussed interchangeably, particularly in conversations about formaldehyde exposure. However, they are not the same, and understanding that distinction is essential for scientific accuracy, public health awareness, and effective policy.
“There seems to be confusion around how different hair products function and what risks they present. Clarity is essential if we want to advance meaningful, science-based safety standards.”
— Amber Makupson, Founder, Clean Beauty Coalition
What are Hair Relaxers
Hair relaxers are products designed to permanently alter the structure of hair by breaking disulfide bonds within the hair shaft.
Traditional relaxers rely on highly alkaline substances, not formaldehyde.
Common substances used in relaxers include:
sodium hydroxide (lye systems)
calcium hydroxide (no-lye systems)
guanidine hydroxide
ammonium thioglycolate (in some systems)
These substances work by restructuring the hair at a molecular level, resulting in permanent straightening.
Traditional hair relaxers typically do not contain formaldehyde.
How are Hair Relaxers Used
Relaxers are applied directly to the scalp and hair and are typically:
left on for a controlled period
rinsed out
followed by a neutralizing process
Because of direct scalp contact and repeated use over time, relaxers are considered a long-term exposure category in cosmetic use.
What are Hair Straightening and Smoothing Treatments
Hair straightening or smoothing treatments — often referred to as:
keratin treatments
Brazilian blowouts
smoothing systems
are designed to temporarily smooth the hair and reduce frizz, rather than permanently restructure it.
These treatments typically involve:
applying a product to the hair
blow drying
sealing the treatment with high heat (flat ironing)
Where Formaldehyde Comes In
Formaldehyde is a volatile organic compound (VOC) that may be present in or released from certain hair smoothing treatments, particularly when heat is applied during the process.
These products may:
contain formaldehyde directly, or
use substances that release aldehyde compounds when heated
When heat is applied, these substances can release vapors into the air, creating an inhalation exposure pathway.
This is why:
salon workers have historically reported respiratory irritation
ventilation and protective measures became part of the conversation
regulatory agencies began issuing guidance
Key Differences in Exposure
Understanding how exposure occurs is critical.
Hair Relaxers
scalp contact exposure
high pH (alkaline systems)
repeated use over time
associated with long-term exposure research
Hair Smoothing Treatments
heat-activated process
airborne exposure during application
associated with inhalation exposure
particularly relevant in salon environments
These are fundamentally different exposure pathways, requiring different scientific and regulatory approaches.
Why This Distinction Matters
Grouping these products together can lead to:
inaccurate public health messaging
confusion in consumer education
misaligned policy discussions
For example:
concerns around relaxers often focus on long-term, repeated use and endocrine-related research
concerns around smoothing treatments focus on inhalation exposure during heat application
Each requires a different lens.
Policy Context: Where This Shows Up in Legislation
This distinction is already reflected in current policy discussions.
Healthy Hair Act
Targets formaldehyde in hair smoothing and straightening treatments, particularly those that release formaldehyde when heat is applied.
Safer Beauty Bill Package
Introduced by:
Rep. Jan Schakowsky
Rep. Lizzie Fletcher
Rep. Ayanna Pressley
Rep. Doris Matsui
This federal package addresses:
hazardous substances
ingredient transparency
occupational exposure
Safer Beauty for Georgians ActThe Clean Beauty Coalition’s state-level effort includes:
formaldehyde and formaldehyde-releasing substances
broader ingredient safety priorities
protections aligned with public health and environmental standards
Disproportionate Impact and Occupational Exposure
Both product categories raise important equity considerations, though in different ways.
Hair Relaxers
historically marketed to Black women and girls
often used beginning at younger ages
associated with repeated, long-term use
supply chain accountability
Smoothing Treatments
commonly performed in salon environments
stylists may perform multiple treatments per day
increased relevance for occupational exposure
Understanding these patterns is essential for equitable safety standards.
What Consumers Should Understand
Consumers should be aware that:
not all hair straightening products function the same way
relaxers and smoothing treatments involve different processes
exposure depends on both formulation and use conditions
Clear communication between stylists and clients is essential to ensure safe and informed decisions.
Clean Beauty Coalition’s Position
At the Clean Beauty Coalition, we believe:
scientific clarity must guide public conversations
different substances require different regulatory approaches
exposure pathways must be clearly understoodboth consumer and occupational safety must be prioritized
Hair relaxers and hair smoothing treatments are often grouped together — but they are not interchangeable.
Understanding the difference is essential to advancing accurate, evidence-based cosmetic safety policy.
Sources & References
U.S. Food & Drug Administration (FDA)
Hair smoothing products that release formaldehyde
National Institutes of Health (NIH)
Environmental health and exposure research
International Agency for Research on Cancer (IARC)
Formaldehyde classification
https://monographs.iarc.who.int
Occupational Safety and Health Administration (OSHA)
Formaldehyde exposure standards
