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My hair has always grown so much faster than the hair of my friends. It was nice when I was trying to grow out my hair, but can be annoying when I have a shorter style that I like and have to go to the salon frequently just to maintain it. This frustration led me to finally research why hair grows so fast in some people but not others.

So why does my hair grow so fast?Hair growth rate varies widely among people. DNA largely determines a person’s hair growth rate. However, it is dependent on many factors including the part of the body, ethnicity, gender, age, stress level, and state of health.

I dove deep into the research and found some surprising things that explain a lot about my hair experiences. Read on to learn who is most likely to have the fastest growing hair.

How Fast Does Hair Grow on Average?

Before you learn why your hair is growing so fast, you may want to know exactly what is normal for human hair growth.

Scalp hair grows at a rate of about 0.6–1.4 cm (.03-.56 in) per month in general. However, hair growing as fast as 3.36 cm/month (1.3 in/month) has also been noted in research.

Here is the average growth rate of hairs on different parts of the body, according to data found in a research paper by Pragst F. Balikova, MA.

Part of Body	Average Growth Rate (mm per day)
Scalp, non-bald	0.32–0.46
Scalp, alopecia	0.08–0.15
Beard	0.25–0.29
Underarm	0.29–0.33
Pubic Area	0.3
Eyebrow	0.15–0.16
Thigh	0.13–0.25
Trunk/Arms/Legs	0.27
Forehead	0.03

Body Hair Growth Rate

If you are wondering about why your body or facial hair is growing so fast, the reason is most likely due to hormones.

Hormones affect hair growth in many ways, including the growth rate. If we are talking about body and facial hair, testosterone often increases the rate of growth and estrogen often decreases it.

This is why women with a lot of facial and body hair often have higher levels of testosterone than other women. Not only does testosterone make hair grow in these places, it makes the hair grow faster.

In addition, substances such as minoxidil, cyclosporin, diazoxide, and
chromakalin can increase the growth rate of body and facial hair.

Scalp Hair Growth Rate

If you are wondering why your scalp hair is growing so fast, then the main reason is likely ethnicity or hair thickness. But other factors may be at play too.

Ethnicity

Hair growth rates vary significantly between ethnicities.

In a large study on the diversity of human hair growth, people of African descent tended to have hair that grew the slowest as well as the thinnest hairs.

People of Asian descent had hair that tended to grow the fastest along with the thickest hairs.

And people with European descent fell in the middle.

Here’s a chart from that study showing the diversity in hair growth speeds.

However, as I cover in the next section, this may be more about hair thickness than ethnicity.

Hair Thickness

In a study of Asian and Caucasian subjects with straight and semi-straight hair, thicker hair fibers corresponded to a faster growth rate. Thin hair fibers had slow growth rates. This finding appeared to be unrelated to ethnic origin.

Another study analyzed 59,765 hairs and found that thin hairs grew slower than thick hairs.

This may explain why Asian people tend to have hair that grows the fastest. They also have the thickest hairs.

If you have thick hair, that explains why your hair is growing so fast. However, just because your hair seems thick doesn’t necessarily mean that it is actually is thick.

Especially if you are of European descent, you may just have dense hair. That means you have more hair follicles spaced close together and a lot of hairs, but they aren’t necessarily thick.

You can tell if your hair is thick by pinching an individual hair between your fingers and feeling it. If you feel nothing between your fingers, you don’t have thick hair.

If instead, your hair feels like some heavy sewing thread, you have thick hair.

Gender

One study of young adults found that the hair growth rate of scalp hair was pretty similar between males and females. However, hair tends to grow significantly slower at the nape in men.

In contrast, another study of Caucasian subjects found that women without pattern hair loss had a faster hair growth rate than men without pattern hair loss.

Overall, it seems that women are probably more likely to have fast-growing hair, but there will be exceptions to this rule.

Age

Hair growth speed can slow with age. Researchers have found that people under 25 have the fastest growth rates.

In other studies, the average growth rate in prepubescent, adolescent, adult, and older adults have been reported at 0.41, 0.30, 0.34, and 0.32 mm/day, respectively.

So very young people tend to have faster-growing hair, but once you reach adulthood, it tends to stay at the same rate.

However, aging can make hairs thinner over time. And as we have learned, thin hairs tend to grow slower.

Environmental Factors

Environmental factors may affect the growth rate of hair, but their influence is very minimal compared to genetics. Your sex and ethnicity are far more important.

In brief, different living conditions in people of the same origins appear to have a very low influence upon their inherent hair growth parameters. 

-Diversity in human hair growth, diameter, colour and shape. An in vivo study on young adults from 24 different ethnic groups observed in the five continents

Stress

Stress is one environmental factor that may impact hair growth rate by causing hair growth inhibition.

In fact, according to Erling Thom, a Dermatology researcher, many stress-related substances can stop hair growth.

Studies have demostrated that certain stress-mediating substances such as substance P, adrenocorticotropic hormone, prolactin, and cortisol actually inhibit the growth of hair.

-Erling Thom

In addition, severe illness may interfere with hair growth.

The good news about having hair that is growing fast is that you are more likely to be a healthy person!

Final Takeaways

If you have fast-growing hair, the main reason is your DNA and hair thickness. Several other things, like environmental factors, age, stress, and medications may have an impact, but your DNA mostly calls the shots in this department.

Related Questions

Why does my hair grow so fast after waxing?

The most likely reason is that the hairs are breaking and not being pulled out by the root. So instead of taking a week or more to show back up, they are growing back in a few days, just like you shaved.

To ensure this doesn’t happen, make sure you aren’t waiting too long to wax. Longer hairs are more likely to break.

Want to remember this? Pin this to your favorite Pinterest board so you can find it later!

References

Agency for Toxic Substances and Disease Registry: Hair Analysis Panel Discussion: Exploring the State of the Science

Clinica Chimica Acta: State of the Art in Hair Analysis for Detection of Drug and Alcohol Abuse

European Journal of Dermatology: Diversity in human hair growth, diameter, color and shape. An in vivo study on young adults from 24 different ethnic groups in the five continents

International Journal of Cosmetic Science: Relationships Between Hair Growth Rate and Morphological Parameters of Human Straight Hair: a Same Law Above Ethnical Origins?

The Journal of Clinical Endocrinology & Metabolism: Effects of Sex Steroid Deprivation/Administration on Hair Growth and Skin Sebum Production in Transsexual Males and Females

Journal of Drugs in Dermatology: Stress and the Hair Growth Cycle: Cortisol-Induced Hair Growth Disruption

Skin Research and Technology: Gender Differences in Scalp Hair Growth Rates are Maintained but Reduced in Pattern Hair Loss Compared to Controls

As a little girl, I was envious AF of Shirley Temple’s curly hair. I dreamed of suddenly growing some gorgeous locks like hers. Since I heard that my mother’s friend developed curly hair as an adult, this seemed like a realistic goal. Unfortunately, that glory day never came for me.

But why does hair become curly with age for some people? Your hair may become curly with age if you inherited both straight and curly hair genes from your parents. Some of these genes can be inactive at birth but then become turned on by hormones, aging, or other factors including medication, nutrition, stress, illness, or pollution.

Science is a long way off from fully understanding what exactly causes hair to be curly and what factors can turn hair from straight to curly with age.

However, there is still a lot we do know. And with that information, you can make some educated guesses about why your hair has suddenly become curly.

What Determines Curly Hair?

Curly hair is largely determined by the hair follicle shape. An asymmetrical hair follicle will produce curly hair in all ethnicities.

Hair follicles are first formed in the first trimester of pregnancy. The shape is determined by your DNA. This shape is thought to be mostly fixed for life, however, genes can be turned on and off by your environment and experiences.

Just as your skin sheds and new skin grows, the hair follicles are going through a similar rebirth all the time. If any of the many genes associated with hair follicle shape is turned on or off, the hair follicle shape can change slightly or on rare occasions, a lot.

We don’t fully understand everything that triggers these hair-related genes to be turned on or off, but scientists do know some things that may help you make sense of your hair changes.

Hormones

Genes can turn on and off for lots of different reasons. These factors are not even completely understood by scientists! But we do know that hormones can turn genes on and off.

–Trisha Chong, Stanford University

Hormones can have huge effects on the body, including the hair. People often see changes in their hair texture when they go through puberty, and hormones are probably one reason for this.

Women going through pregnancy often notice changes to both their skin and hair. Pregnancy hormones play a role in these changes, so may possibly play a role in straight hair suddenly turning curly.

Keep in mind that women’s bodies produce pregnancy hormones each menstrual cycle as well as when using some forms of birth control. So even if you aren’t pregnant, pregnancy hormones could play a role in changes to your body.

Another cause of changing hormones is menopause. However, it’s more likely to see thinning hair than straight hair becoming curly during this phase of life.

Aging

Aging affects the hair follicles, but it is rarely a cause of curly hair. However, aging does make hair strands finer. This means gravity isn’t pulling each hair down as much. Lighter hair will make wavy or curly hairs become more apparent.

This is something I’ve noticed myself as I’ve aged. My hair was always a little wavy, but it was crazy thick when I was a child and adolescent. So I would have some waves if I kept my hair short, but if I grew it out very much, there were no waves to be found.

When I hit my 30’s, I noticed that my hair was becoming slightly lighter and my waves were obvious even when my hair was long.

The same thing could happen with people who have thick hairs but curl producing hair follicles, especially women who have had long hair their whole lives. As they age, the curls will become more curly and noticeable.

Changes in Nutrition

Factors such as genetic variation, weathering, diet or cosmetic treatments affect the constitution of the hair and underlie the variations in hair characteristics across hair ethnic groups, such as diameter, ellipticity and curliness.

-Human Hair and the Impact of Cosmetic Procedures: A Review on Cleansing and Shape-Modulating Cosmetics

Although there have been no direct links made between what you eat and hair becoming curly, nutrition has an impact on other aspects of hair including texture and strength. So if you changed your diet significantly before the onset of curly hair, that may be the cause.

Just as aging makes hair thinner, so can a poor diet. And thinner hair can be more wavy and curly than thicker hair.

In addition, copper has been linked to curly hair in some studies. Have you been eating a lot of high copper foods like lobsters, oysters, or liver?

Or perhaps you started a multivitamin high in this mineral? That may have something to do with your change in hair texture.

Medications

Medications for seizures and bipolar disorder, on rare occasions, can cause curly hair. The reason for this is still unknown, but some researchers have speculated that it has to do with how metals are processed in the body. Changes in the concentration of metals like copper are seen in the hairs of these patients.

Sometimes hair becomes straight again after they stop using these medications, but there have been reports of patients continuing to have curly hair even after discontinuing their medication.

Some medications used to treat cancer, called epidermal growth factor receptor inhibitors, can also affect hair texture. This can result in hair becoming straight or curly.

And just as hormones may impact hair texture, any medications that affect hormones, such as glucocorticoids or thyroxine, could also potentially make hair become wavy or curly.

Illness and Stress

Both illness and stress can take a toll on the body. Hormone levels are often altered by illness or stress. This is why people who are chronically ill or under a lot of stress often have thinning hair or hair loss.

These changes in your body could possibly affect gene expression, which could change your hair texture.

In addition, some specific illnesses, like hyperthyroidism, are linked to changes in hair texture.

Pollution

Pollution has been linked to hair loss in some studies. It’s common in some areas of the world for people to experience hair loss when moving from rural areas to highly industrialized cities with lax pollution standards, like in China.

There are no studies linking curly hair to pollution. However, pollution can affect our hormone levels. And as we have learned, hormones may have an effect on hair texture. So it’s something to think about if your hair changes started after you moved to a more polluted environment.

Climate

Did you move to a different climate? Things like temperature and sun exposure can affect hormone levels, so that maybe what’s going on.

Or it could be the new climate directly affecting your hair.

Just as curly hairs typically curl the most when wet, humidity in the air brings out waves or curls in hair.

So if you lived in a desert your whole life and suddenly moved to a humid area like the Southern US, for example, you’d likely notice that your hair is more wavy or curly.

Whose Hair Is Most Likely to Become Curly With Age

We know from genetic studies that people with African ethnicity are most likely to hair curly hair at birth. So of course, their hair isn’t going to suddenly become curly. However, it could become more curly with age.

In contrast, most people with East Asian ethnicity are likely to have very straight hair. Genetically, it’s unlikely that they have any genes that will suddenly make their hair wavy or curly.

People with Western Asian or European DNA, however, are the most likely to have a mix of genes that would create straight hair that becomes curly with age.

Of course, if your ethnicity is some mixture of African, Asian, and European, it’s also more likely that you have a mixture of genes that could mean your hair will change as you age.

Final Takeaways

Unfortunately for little girls born without curly hair, like me, it’s rare for hair texture to change significantly with age. Yet, it still happens in rare occasions for some people.

We still don’t know that much about hair texture and genetics. But anything that can change gene expression may have an effect on your hair, no matter what age you are. If your hair has suddenly changed from straight to curly, it’s likely due to hormones or changes in your environment. It’s most likely a permanent change, but not always.

So make the most with what the good Lord gave you and enjoy those curls while you got them. And if you hate your new glorious curls, just remember, I’m envious of you! I guess we usually want what we don’t have! That’s why there are also great hair straighteners in the world, like this one. 😉

Related Questions:

Can hair change from curly to straight?

Yep! Just as straight hair sometimes becomes curly, curly hair can sometimes become straight. However, this tends to be a rare occurrence as hair follicle shape and hair texture is mostly fixed by birth.

How to change hair follicle shape naturally?

There is no known way to do this, unfortunately. I looked and looked. But you can bet there is a billion-dollar cosmetics industry trying to figure it out, so maybe we will know one day!

What’s the best hair removal method for busy women with lots of responsibilities?

I personally have found epilation to be the best hair removal method for my busy life. The results last as long as waxing, but it’s much cheapers and easier to do at home. I used to have to shave every day, but now hair removal takes a fraction of that time.

To learn more about epilation, check out the Epilator FAQ and Beginner’s Guide.

Want to remember this? Pin this to your favorite Pinterest board so you can find it later!

References:

Cosmetics: Human Hair and the Impact of Cosmetic Procedures: A Review on Cleansing and Shape-Modulating Cosmetics

Clinical Psychopharmacology and Neuroscience: Curly Hair Induced by Valproate in Bipolar Disorder

Epilepsia: Valproic Acid–induced Hair‐texture Changes in a White Woman

Experimental Dermatology: The Biology and Genetics of Curly Hair

JAMA Dermatology: Hair and Nail Changes during Long-Term Therapy with Ibrutinib for Chronic Lymphocytic Leukemia

Journal of the American Academy of Dermatology: Hair Disorders in Patients with Cancer

Standford Medicine: Other Traits

Trends in Genetics: The Secret Life of a Hair Follicle

U.S. National Library of Medicine: Aging Changes in Hair and Nails

U.S. National Library of Medicine: Is Hair Texture Determined by Genetics?