Hair relaxers are not good for your hair in a structural sense. They work by breaking the internal bonds that give hair its natural shape, and that process permanently weakens every strand it touches. The straightening effect is real, but it comes at a measurable cost to hair strength, elasticity, and scalp health. Whether that tradeoff is worth it depends on your priorities, but understanding exactly what relaxers do helps you make that choice with clear eyes.
How Relaxers Change Your Hair
Your hair gets its shape from protein bonds called disulfide bridges deep inside the hair shaft. These bonds hold the spiral structure of keratin, the protein that makes up hair. A relaxer uses a strongly alkaline chemical, typically with a pH between 12 and 13, to swell the hair and pry open the outer cuticle layer. Once inside, the active ingredient breaks those disulfide bridges apart, making the hair soft and pliable enough to be combed straight. The bonds then reform in a new, straightened position.
There are two main types. Lye relaxers use sodium hydroxide and work through a process called lanthionization, which permanently replaces about a third of the hair’s cystine (a key amino acid) with a different, weaker cross-link. No-lye relaxers often use ammonium thioglycolate, which selectively weakens cystine bonds without disrupting the entire protein structure. This type requires a separate neutralizing step with hydrogen peroxide to lock the new shape in place. No-lye formulas cause less overall protein disruption, but both types permanently alter the hair’s internal chemistry.
The Damage Is Measurable
Research using electron microscopy shows clear structural damage after relaxer treatment. The cuticle, your hair’s protective outer layer, develops irregularities, fissures, and partial detachment. These aren’t cosmetic imperfections. A damaged cuticle means the softer interior of the hair shaft is exposed to friction, heat, and environmental stress with less protection.
The numbers tell the story. Tensile strength, meaning how much force hair can withstand before breaking, decreases across all hair types after chemical straightening. Studies on Afro-textured hair found a 71% reduction in the energy needed to comb through treated strands, which sounds like a benefit until you realize it reflects how much weaker and more fragile the hair has become. Protein integrity drops too: levels of tryptophan, an amino acid that serves as a marker for protein health, decline after treatment. At the chemical level, researchers have documented increased cysteine damage, dehydration of protein side chains, and elevated cysteic acid, all signs that the hair’s core structure has been compromised.
With repeated treatments, these effects compound. Multiple relaxer sessions are associated with increased frizz (the very problem people are trying to solve), thinning and weakening of the hair shaft, split ends, and breakage. One study of a commercial relaxer brand found hair breakage or loss in 95% of users evaluated.
Effects on Your Scalp
The scalp takes damage too. Relaxers with a pH above 12 are caustic enough to irritate skin on contact, which is why burning during application is so common. Repeated chemical exposure can cause scalp flaking, irritation, and inflammation around hair follicles.
There’s a more serious concern for people who use relaxers long term. Central centrifugal cicatricial alopecia (CCCA) is a form of permanent, scarring hair loss that begins at the crown and spreads outward. It disproportionately affects Black women. While researchers initially believed relaxers were a direct cause, the condition has also been found in women who never used chemical products, suggesting the relationship is more complex. Current understanding is that chemical relaxers may allow irritants or bacteria to enter damaged follicles, triggering an inflammatory cascade that eventually destroys the follicle and replaces it with scar tissue. Dermatology guidelines recommend that people with signs of CCCA avoid regular relaxer use, as it’s associated with increased disease incidence.
Chemicals Beyond the Active Ingredient
The alkaline agent that straightens your hair isn’t the only chemical worth thinking about. Laboratory testing of hair products marketed to Black women found that relaxers, root stimulators, and hair lotions frequently contained endocrine-disrupting chemicals. These included nonylphenols, parabens, diethyl phthalate, bisphenol A, and several other phthalates. Endocrine disruptors interfere with hormone signaling in the body, and scalp skin is particularly absorptive because of its rich blood supply and the follicle openings that relaxers widen during treatment.
A large study from the National Institute of Environmental Health Sciences tracked nearly 34,000 women over several years and found that those who used straightening products had an 80% higher rate of uterine cancer compared to women who never used them. For frequent users, defined as more than four times in the previous year, the risk was even sharper: roughly 2.5 times higher than non-users. These were the first epidemiological findings linking straightening products to uterine cancer, and they prompted the FDA to propose banning formaldehyde and formaldehyde-releasing chemicals from hair smoothing and straightening products sold in the United States. That proposed rule, announced in 2024, specifically cites both short-term effects like breathing problems and sensitization reactions, and long-term risks including increased cancer rates.
How to Minimize Damage If You Use Relaxers
If you choose to continue relaxing your hair, spacing and technique matter more than anything else. The standard recommendation is to wait at least 6 to 8 weeks between touch-ups, and many stylists encourage stretching to 10 or 12 weeks when possible. Relaxing too soon risks overlapping the chemical onto previously treated hair, which is already weakened and cannot tolerate a second round of bond-breaking without severe breakage.
Every touch-up should be applied only to new growth, the section of hair closest to the scalp that hasn’t been chemically treated yet. Overlapping onto already-relaxed lengths is one of the most common causes of mid-shaft breakage and thinning. A skilled stylist will coat previously relaxed ends with a protective barrier before applying product to the roots.
Deep conditioning after every treatment helps replace some of the moisture and flexibility that the process strips away, though it cannot rebuild the broken disulfide bonds. Limiting heat styling between treatments also reduces cumulative stress on hair that’s already structurally compromised. Protein treatments can temporarily reinforce weakened strands, but they’re a patch, not a fix. The chemical change from relaxing is permanent, and no conditioner reverses it.
Alternatives Worth Considering
If your main goal is manageability or a smoother texture, several options cause less structural damage than traditional relaxers. Keratin treatments (sometimes called Brazilian blowouts) use lower temperatures and coat the hair rather than breaking internal bonds, though many formulas contain formaldehyde or formaldehyde-releasing chemicals, which carry their own health risks. Pressing or flat ironing offers temporary straightening without chemical alteration, but frequent heat use still damages the cuticle over time.
Protective styling, twist-outs, braid-outs, and simply learning to work with your natural texture avoid chemical damage entirely. The shift toward natural hair care over the past decade has produced a much wider range of products designed to define and moisturize curls and coils without straightening them. For many people, the tradeoff of convenience that relaxers offer simply doesn’t hold up once they understand the cumulative cost to their hair and potentially their health.