Common Causes of Hair Loss in Women
Hair loss in women can happen for many different reasons. Understanding the underlying cause is important, because the best treatment depends on what is triggering the shedding.
Some of the most common causes include the following.
Telogen Effluvium
Telogen effluvium is one of the most common causes of sudden hair shedding. It occurs when a large number of hair follicles enter the resting phase of the hair cycle at the same time.
This type of hair loss often happens 2–3 months after a physical or emotional stressor.
Common triggers include:
• Significant life stress
• Illness or surgery
• Rapid weight loss
• Medication changes
• Hormonal shifts
• Nutritional deficiencies
The good news is that telogen effluvium is usually temporary, and hair growth typically returns once the underlying trigger improves.
Iron Deficiency
Low iron stores are a very common contributor to hair shedding, particularly in women with heavy menstrual cycles.
Even when hemoglobin levels are normal, low ferritin levels (iron storage) can affect hair growth.
Symptoms that may occur alongside iron deficiency include:
• Fatigue
• Hair shedding
• Pale skin
• Exercise intolerance
Hormonal Changes
Hormonal shifts can affect the hair growth cycle.
Common hormonal triggers include:
• Perimenopause
• Postpartum hormone changes
• Thyroid disorders
• Polycystic ovary syndrome (PCOS)
These changes can cause hair follicles to spend less time in the growth phase, leading to thinning or shedding.
Thyroid Disorders
Both hypothyroidism and hyperthyroidism can contribute to hair loss.
The thyroid gland helps regulate metabolism and many body systems, including the hair growth cycle.
Hair loss from thyroid disorders is often diffuse, meaning it occurs across the entire scalp rather than in specific patches.
Androgenetic Hair Loss (Female Pattern Hair Loss)
Female pattern hair loss is a genetic form of hair thinning that tends to occur gradually over time.
It typically presents as:
• Thinning at the crown
• Widening of the hair part
• Reduced hair density
Unlike telogen effluvium, this type of hair loss tends to be progressive rather than sudden.
When should you see a healthcare provider for hair loss?
You should consider medical evaluation if you notice:
• Sudden or severe hair shedding
• Hair loss associated with fatigue or weight changes
• Patchy hair loss
• Hair thinning that continues to worsen over time
Blood tests can help identify common causes such as iron deficiency or thyroid dysfunction.
How Long Does It Take for Hair to Grow Back?
Hair grows in cycles, which means that hair regrowth usually takes time. When hair loss occurs due to stress, illness, or nutritional deficiencies, the hair follicles often need several months to return to a normal growth pattern.
Most hair follicles cycle through three phases:
Growth phase (anagen):
This is the active growth phase when hair is actively growing from the follicle. This phase can last several years.
Resting phase (telogen):
During this phase, the hair stops growing and prepares to shed.
Shedding phase:
The hair falls out, and a new hair begins growing in the follicle.
Because of this cycle, hair loss often appears 2–3 months after the triggering event, and regrowth may take 3–6 months to become noticeable.
What to Expect During Hair Regrowth
As hair begins to regrow, many people notice:
• Short “baby hairs” along the hairline
• Less hair shedding during washing or brushing
• Gradual improvement in hair thickness
Hair growth is usually slow and steady, growing about ½ inch per month.
When Hair Loss May Take Longer to Improve
Hair regrowth may take longer if the underlying cause has not been addressed. This can include:
• Iron deficiency
• Thyroid disorders
• Ongoing stress
• Hormonal changes
• Nutritional deficiencies
Identifying and addressing the underlying trigger is often the most important step in improving hair health.
Supporting Healthy Hair Growth
In addition to addressing underlying causes, certain nutrients may help support healthy hair follicles and the hair growth cycle. This is where targeted supplementation may be helpful.
The supplements below are commonly used to support hair health and may be helpful depending on the underlying cause of hair shedding.
