Hormones have the most impact on hair growth. They can alter how much hair grows, how much stops growing and how much is shed. To begin understanding how hormones affect the growth of hair it’s important to know the stages of hair growth.
Stage 1- ANAGEN is the GROWTH stage. On average about 85% of the hair is in this stage at one time. This stage lasts about 2-6 years.
Stage 2- CATAGEN is the SHEDDING stage. On average 1-3% of the hair is in this stage at one time. This stage last about 2 weeks.
Stage 3- TELEGEN is the RESTING phase. On average about 15% of hair is in this stage at one time.This stage lasts about 1-4 months.
Hormonal changes can dramatically affect any of these stages! The following are the most common hormonal changes.
PREGNANCY during and after has a major affect on the hair. Hair is at its fullest and most luminous stage during pregnancy! This is because more hair is in the growth stage due to estrogen and progesterone levels. However, about 3-5 months after pregnancy shedding and resting stages go back up and cause what seems like excessive hair loss mainly around the hairline. No worries! This hair will grow back once hormones return to a normal level.
THYROID GLAND function affects hair growth whether it is over-active or under-active (hyper/hypo-thyroidism). Either of these can cause the hair to be dry, brittle, and enter more hair into the shedding stage. Other conditions such as uncontrolled diabetes and lupus can also cause hair loss or cause the hair to be fine. Once controlled or treated hair growth usually returns to normal.
MEDICATIONS also interfere with hormone levels and can cause hair loss. Birth control, blood pressure, antidepressant, arthritis medications and anesthesia all have an adverse affect on hair growth stages. Sides effects (forced shedding stage) of medication will normally show up between 2-6 months after the start or finish of the medication.
STRESS is one of the most overlooked cause of hormonal changes. This is mainly because the effects of a traumatic experience don’t normally show until 2-3 months after. Fret not! This hair grows back!
AGE will affect the overall growth rate and texture of hair. Puberty increases hormone levels often increasing hair growth over the entire body. For men and women after age 40 testosterone decreases causing hair growth to slow down. For women estrogen levels can dramatically decrease causing hair growth to slow and/or be thinner. At this time it is important to change to using shampoos and conditioners that increase volume.