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Can hormones change the color of your hair?

Hair color is determined by the amount and distribution of melanin pigments in the hair shaft. Melanin is produced by melanocytes, specialized pigment-producing cells located in the hair follicles. The two main types of melanin are eumelanin (which produces brown and black hues) and pheomelanin (which produces red and blonde hues). Genetics play a major role in determining hair color, but other factors like hormones, age, and environment can also impact hair pigmentation.

How Do Hormones Affect Hair Color?

Hormones like estrogen, progesterone, thyroid hormones, and melatonin can influence hair color by affecting melanin production and the hair growth cycle:

  • Estrogen – Higher estrogen levels during pregnancy can lead to darker, thicker hair. Estrogen may stimulate melanocyte activity.
  • Progesterone – May competitively inhibit estrogen receptors and lead to reduced melanogenesis.
  • Thyroid hormones – Both hyperthyroidism and hypothyroidism can trigger temporary hair darkening or lightening.
  • Melatonin – This sleep hormone also triggers hair pigment changes in animals by regulating melanin synthesis.

In addition, hormones that slow the hair growth cycle, like estrogen in pregnancy, may allow more time for melanogenesis and result in darker hair.

Does Hormonal Contraception Change Hair Color?

Hormonal contraceptives like birth control pills, implants, shots, intrauterine devices (IUDs), and vaginal rings commonly use estrogen and progesterone to prevent pregnancy. By influencing hormone levels, it is possible that contraceptives may also impact hair pigmentation.

However, the evidence is mixed when it comes to hormonal birth control and hair color changes:

  • Some studies have found no significant association between oral contraceptives and hair color changes.
  • Other reports indicate oral contraceptives may be linked to darkening of hair color in premenopausal women.
  • A few cases link hormonal IUDs like Mirena to hair darkening during use.
  • There are also anecdotal reports of hair lightening after stopping hormonal birth control.

Overall, more research is still needed to conclusively determine if and how specific types of hormonal contraceptives may influence hair pigmentation.

Does Pregnancy Change Hair Color?

Hair color changes during pregnancy are common. Most women experience darkening of hair during pregnancy. The reasons for this hair darkening may include:

  • High estrogen levels – Estrogen increases during pregnancy and can stimulate melanocyte activity.
  • Progesterone effects – Progesterone levels also rise, which may allow relatively higher estrogen levels.
  • Increased hair growth phase – Continued hair growth due to pregnancy hormones allows more time for melanogenesis.
  • Higher circulation – Improved circulation and nutrients during pregnancy may promote melanin synthesis.

A study of over 200 pregnant women found 63% experienced darkening of hair during pregnancy. Of these women:

Hair Color Before Pregnancy Percentage Who Experienced Darkening
Blonde 90%
Red 43%
Light brown 80%
Dark brown/black 10%

This data indicates blonde, red, and light brown hair is more likely to darken during pregnancy compared to already dark brown or black hair.

Does Hair Return to Normal Color After Pregnancy?

In most cases, the hair darkening observed during pregnancy is temporary. Within 6 months after giving birth, hair color typically returns to pre-pregnancy or normal baseline pigmentation.

However, a small percentage of women may experience permanent hair color changes after pregnancy. One study found that around 6% of women retained darker hair coloring postpartum.

Can Menopause Lighten Hair Color?

Shifts in hormones during menopause can also influence hair pigmentation. The decline in estrogen levels during menopause is associated with graying and lighter hair in some women.

A study of hair color and menopause found:

  • Before menopause, only 23% of women reported gray hair.
  • Within 5 years after menopause, 75% of women reported graying hair.

Animal studies also indicate estrogen deficiency is linked to depleted melanocyte function and lower melanin production.

In addition to hormonal changes, other factors like aging, genetics, and oxidative stress may contribute to graying hair and changes in hair pigmentation after menopause.

Can Thyroid Disorders Change Hair Color?

The thyroid gland regulates metabolism by releasing hormones like triiodothyronine (T3) and thyroxine (T4). Both hypothyroidism and hyperthyroidism have been associated with hair color changes:

  • Hypothyroidism – Insufficient thyroid hormone levels can cause generalized darkening of hair.
  • Hyperthyroidism – Elevated thyroid hormone levels may trigger diffuse lightening of hair.

However, hair color changes due to thyroid dysfunction are typically temporary. With treatment of the thyroid disorder, hair color often returns to normal.

Mechanisms of Thyroid Hormone and Hair Pigmentation

Thyroid hormones appear to impact hair color through several mechanisms:

  • Melanin production – T3 and T4 may alter tyrosinase activity and melanogenesis.
  • Hair cycling – Thyroid hormones influence progression of hair through growth phases.
  • Gene expression – Thyroid hormones regulate expression of hair pigmentation genes.

Can Vitiligo Cause Hair Color Loss?

Vitiligo is a chronic autoimmune skin disorder characterized by patchy loss of skin pigmentation. The cause is believed to involve immune cells attacking and destroying melanocytes.

In addition to white patches on the skin, vitiligo can also cause poliosis – a localized loss of pigment from head hair, eyebrows, eyelashes or body hair. This results in streaks or patches of white hair.

Estimates range from 30-50% of people with vitiligo experiencing poliosis. Any hair can be affected, but graying typically first appears at scalp hair temples and spreads across the head. Eyelashes, eyebrows and facial hair are also frequently involved.

Treatment of Vitiligo Hair Poliosis

Treatment options for vitiligo-related poliosis are limited. However, some potential approaches include:

  • Topical medications like steroids, calcineurin inhibitors
  • Camouflage products like hair sprays, dyes, powders
  • Micropigmentation – cosmetic tattooing to darker areas

But repigmentation success is variable. Those with stable, non-progressing vitiligo may have better outcomes.

Can Alopecia Areata Cause Hair Color Changes?

Alopecia areata is an autoimmune disorder that involves patchy hair loss, usually from the scalp but sometimes other areas. It occurs when the immune system incorrectly attacks the hair follicles, causing sudden hair shedding.

In some cases, the hair may regrow quickly. But it may be white hair initially, before recovering normal pigmentation. This temporary depigmentation is believed to be related to the autoimmune inflammation halting melanin production.

Among people with alopecia areata:

  • Around 10-30% may experience white hair regrowth before normal pigmentation returns.
  • White regrowth may be more common with severe hair shedding.
  • Hair color typically returns within 6 months as melanocyte function recovers.

Treatment is not required for temporary hair whitening. But treatments like steroids, immune modulators can help manage the underlying alopecia areata.

Can Stress Cause Hair Color Changes?

High stress levels raise cortisol production, which can have wide-ranging effects on the body. There are claims that stress may also alter hair pigmentation and cause graying.

But the direct scientific evidence linking stress to gray hair is limited. While stress can disrupt many body processes, it has not been definitively shown to degrade melanocytes or speed hair graying.

Any association between stress and hair color is likely indirect. For example, stress may cause other changes, like hair loss, that can expose gray hairs. Or stress may worsen medical conditions that can deplete hair pigmentation.

Managing stress levels through lifestyle, diet, and mental health support is still beneficial. But claims that reducing stress alone reverses gray hair are not yet substantiated.

Do Hair Dyes, Sun Exposure, Smoking Impact Hair Color?

Other external factors like hair dyes, sunlight, smoking can affect hair color over time:

  • Hair dyes – Frequent use of chemical hair dye can damage hair over time, causing dryness, brittleness and increased graying. But semi-permanent dyes with lower peroxide cause less damage.
  • Sun exposure – UV radiation can degrade hair protein and melanin, causing bleaching effects.
  • Smoking – Cigarette smoking is linked to premature hair graying. Toxins may increase oxidative stress and aging.

The Takeaway

Hair color is complex and influenced by many genetic, health, and lifestyle factors. Hormonal changes related to pregnancy, menopause, thyroid disorders can temporarily alter hair pigmentation.

While hair coloring from hormones is usually reversible, some permanent shifts can occur. Avoiding cigarette smoking, excessive sunlight, and reducing stress may help maintain normal hair pigmentation.

If concerned about progressive hair color changes, it is best to see your healthcare provider to assess for any underlying conditions.