This is one of those topics where I want to be careful about staying in my lane. I’m a stylist, not an endocrinologist. But I see the effects of thyroid problems in my chair constantly — and I’ve learned enough over the years to know when to say “you should get your thyroid checked.”
How thyroid issues show up in hair
Both hypothyroidism (underactive) and hyperthyroidism (overactive) can cause hair changes. The most common presentation I see: diffuse thinning all over the head, hair that’s become drier and more brittle than usual, slower growth, and sometimes changes in texture — curly hair going straighter or vice versa.
With hypothyroidism specifically, the outer third of the eyebrows can thin noticeably. If a client mentions thinning hair AND thinning eyebrows, I always suggest thyroid testing.
Why it happens
Your thyroid regulates metabolism throughout your body, including your hair follicles. When thyroid hormones are off — either too high or too low — the hair growth cycle gets disrupted. More follicles enter the resting phase, fewer new hairs grow in to replace them, and the hairs that do grow tend to be finer and more fragile.
The tricky part is that hair changes usually lag 2–3 months behind the thyroid issue. By the time you notice the thinning, the problem has been going on for a while.
The testing conversation
If you suspect a thyroid issue, ask your doctor for a complete thyroid panel — not just TSH. You want TSH, Free T3, Free T4, and thyroid antibodies (TPO and TG). Some women have “normal” TSH but elevated antibodies, which indicates Hashimoto’s thyroiditis — an autoimmune condition that can cause hair loss even before other thyroid numbers go out of range.
Push for the full panel. A lot of primary care doctors only run TSH, and that doesn’t always tell the whole story.
Recovery takes patience
Once thyroid levels are properly managed with medication, hair typically starts improving — but slowly. We’re talking 6–12 months to see meaningful regrowth. The follicles need time to shift back into the active growth phase.
During that recovery period, be gentle with your hair. Minimize heat, avoid harsh chemical processes, and use bond-strengthening treatments like K18 to protect what you have while new growth comes in.
What I can and can’t do
I can’t diagnose you. I can’t treat you. What I can do is notice patterns and be honest with you about what I’m seeing. If your hair has changed in ways that don’t match your styling habits, product routine, or recent life events, something internal might be going on.
I’d rather send you to your doctor unnecessarily than not say anything and watch you lose more hair. That’s just how we operate at Reverie — we look at the whole picture.
If you’re dealing with unexplained hair changes, book a consultation. We’ll give you an honest assessment and point you in the right direction — whether that’s a new product or a doctor’s appointment.
