Do Hair Relaxers Really Cause Uterine Fibroids? What the 2026 Study Found

Recent research says yes, there's a real link but not proof of direct cause. A 2026 Boston University study found that Black women who used chemical relaxers, especially temporary and keratin formulas, showed higher rates of uterine fibroids and larger fibroid growth than non-users. Scientists call this an association, not a guarantee. The risk builds slowly, over years of repeated use, not from a single salon visit. 

Here's what that actually means for your hair routine and what you can do about it. 

Why This Question Feels So Personal 

I'll be honest: the pushback I hear most about relaxers isn't about the science. It's about identity. Stopping a routine you've used for fifteen, twenty years doesn't feel like swapping shampoo brands. It feels like giving something up. "Will I still look like me?" That question deserves an answer before anyone gets told to change what's worked for them their whole life. 

So, let's start with what's actually in the bottle. 

What's Really in a Relaxer? 

A hair relaxer works by breaking down the protein bonds that give curly and coily hair its natural shape. That's how it makes hair lie flat. You'll find four main types on shelves: 

All four sit inside the "temporary relaxer/keratin" category the study flagged as carrying the strongest fibroid link. 

Inside the 2026 Study 

Boston University tracked around 1,700 Black women using repeated ultrasounds over several years. Recent relaxer users showed a higher fibroid risk and bigger fibroid growth. Temporary and keratin formulas scored worse than permanent ones. Hair dye use was tied to a 44% jump in fibroid incidence. The suspected culprits: phthalates, phenols, and parabens chemicals known to disrupt hormones. Researchers use the word "associated," not "causes." That distinction matters, and I'm not going to pretend it doesn't. 

Your Scalp Isn't a Barrier - It's a Fast Lane 

Here's the part most people skip past. The scalp is one of the most permeable, blood-vessel-dense stretches of skin on your entire body. That's exactly why medicated scalp treatments work so fast. It's also why what touches your scalp doesn't just sit there. It gets absorbed. A scalp-first approach to hair care treats that permeability as the whole point, not a footnote. 

One Bottle Won't Do It - But Years Might 

Endocrine disruptors don't follow a simple "more exposure, worse outcome" rule. Small doses, repeated over years, add up quietly. The effect often shows up long after the exposure that mattered. That's why no single relaxer appointment is "the cause." It's also exactly why switching now still counts, even if you've relaxed your hair for decades. 

The Herbal Trade-Off, Stated Honestly 

No herbal treatment restructures the hair shaft the way a relaxer does. A relaxer gives you straight hair in one sitting. That's instant. The cost is the exposure above. Herbal hair treatments work slower they support the scalp and the strand so what grows in is stronger over months, not one appointment. That's delayed gratification aimed at a different goal. It's not a downgrade. It's a different bet. 

Swapping Out, Step by Step 

Here's how the substitutions actually break down, by what they replace: 

The Herbs Doing the Actual Work 

Curious which combination fits your hair texture? That's worth figuring out before you overhaul your whole routine. 

If You're Not Ready to Quit Relaxers Yet 

This isn't about panic. It's about an informed choice. Ask what's actually in your formula. Space out treatments instead of stacking them every six weeks. Prioritize products without formaldehyde-releasing preservatives or hormone-mimicking ingredients. And don't treat your scalp in isolation bloodwork, stress, sleep, and hydration all feed into the same hormonal picture the study is pointing at.