Can Hormones Really Affect Curly Hair?

Your hair has stopped behaving like your hair.

You blame the shampoo or wonder if you used too much heat. Still, the new growth looks different. This can feel especially disorienting after pregnancy or during another hormonal shift, when straight hair begins to bend or familiar curls start growing looser.

The explanation may sit beneath the scalp. Hair follicles respond to hormones, which can affect growth and shedding. They may also influence the thickness and texture of the next strands your follicles produce.

So if your hair suddenly feels unfamiliar, you may not have caused it. Your body changed, and your hair may be responding with it.

The change begins at the root

Every strand is formed inside a follicle beneath the scalp. Its shape is decided before it reaches the surface.

Researchers examining human hair found that curls begin through uneven growth inside the hair bulb. That unevenness creates the bend of the strand as it forms. (British Journal of Dermatology)

Once a strand has left the scalp, hormones cannot reach back and reshape it. They can, however, affect what the follicle produces next.

This is why the roots matter. New growth that looks different may point to a change within the follicle. Ends that have become rougher or looser are more likely to reflect heat, colouring, tension or everyday wear.

What hormones can change

Hair follicles respond to hormonal signals, including oestrogen and androgens. Those signals can affect how long a hair keeps growing, when it begins resting and how thick the next strand becomes. (Journal of Investigative Dermatology)

Different follicles can also respond differently to the same hormone. Research into oestrogen and human hair follicles found that the response varied depending on the follicle being studied. (Journal of Investigative Dermatology Symposium Proceedings)

That helps explain why there is no universal hormonal hair change. One person may notice more curl. Another may see a familiar pattern loosen. For many, the biggest difference will be shedding or density rather than shape.

Pregnancy gives us the clearest example

Pregnancy is one of the better studied examples of hormones changing hair behaviour.

A study involving 116 participants found that more hairs remained in the active growth stage during pregnancy. After delivery, more moved into the resting stage, which helps explain the shedding many people experience postpartum. (Journal of the European Academy of Dermatology and Venereology)

The change in growth and shedding is well supported. Changes in curl pattern have not been studied nearly as closely.

That does not make someone’s experience imaginary. It means science can explain why pregnancy affects hair while remaining less certain about how often it makes hair straighter or curlier.

Can straight hair begin growing curly?

It can.

Doctors have documented rare cases in which adult hair began growing with a different shape. Certain medications have also been associated with new curling. In one report, two people with previously straight hair developed curls while taking alitretinoin. (Drug Safety Case Reports)

These cases do not prove that an ordinary hormonal shift will change everyone’s texture. They do show that an adult follicle is capable of producing a different strand.

Before changing your entire routine

Look at the new growth first.

If the roots have changed across much of your head, the follicle may be producing different hair. If the roots look familiar while the ends have changed, consider damage, length and product buildup.

Shedding can alter the way hair sits too. With less density, curls and waves may fall differently even when their natural shape has remained the same.

If your hair has become finer, use less product and notice how it responds. If a new wave or curl is appearing, heavy layering may pull it down before you get the chance to understand it.

A sudden texture change accompanied by significant shedding, scalp pain or other changes in your health is worth discussing with a qualified healthcare professional. Hair products can support the strand. They cannot diagnose why the follicle changed.

And if your straight hair has recently become wavy or curly, welcome to this side of it. We have plenty to share with you. 

At Chryosis, we care for the hair currently growing, even when it is different from the hair you remember.