Why Is My Hair Thinning or Falling Out? 10 Possible Causes You Should Know

Finding more hair than usual in your brush, shower drain, or on your clothes can be unsettling. Maybe your ponytail feels smaller than it used to. Maybe your part is getting wider. Or perhaps you’re noticing significantly more shedding every time you wash your hair.

If you’ve been searching “Why is my hair thinning?” or “Why is my hair falling out?”, you’re certainly not alone.

Hair loss isn’t one condition with one solution. It can be influenced by hormones, thyroid function, nutrition, genetics, stress, illness, medications, autoimmune conditions, and other factors.

That’s why simply buying another hair-growth supplement isn’t always the answer.

At Pro Health Functional Medicine in Chandler, Arizona, we believe the first question should be:

What could be contributing to the hair loss in the first place?

Here are 10 possibilities worth investigating.

1. Hormonal Changes

Hormones can play an important role in hair growth and shedding.

Women may notice changes in their hair during:

• Perimenopause

• Menopause

• Pregnancy and postpartum

• Changes in hormonal medications

• Conditions such as PCOS

  
  

For women in their 40s and 50s especially, hair may become finer, the part may widen, or overall density may decrease.

Rather than assuming hair loss is simply part of getting older, it may be worthwhile to discuss your symptoms and hormone health with your healthcare provider.

When medically appropriate, Pro Health Functional Medicine offers hormone evaluation and hormone replacement therapy (HRT) as part of an individualized approach to women’s health.

2. Thyroid Problems

Your thyroid helps regulate metabolism and influences many systems throughout your body—including your hair.

Both thyroid disease and changes in thyroid function can be associated with hair thinning or shedding.

Hair changes may occur alongside other symptoms such as:

• Fatigue

• Feeling unusually cold

• Weight changes

• Constipation

• Dry skin

• Changes in heart rate

• Menstrual changes

  
  

Because these symptoms overlap with many other conditions, laboratory testing can be an important part of the evaluation.

At Pro Health, comprehensive lab testing and thyroid evaluation can help determine whether thyroid function may be contributing to your symptoms.

3. Iron or Other Nutrient Deficiencies

Your hair follicles require adequate nutrition to grow.

Insufficient iron, protein, zinc and certain other nutrients can contribute to hair loss. Very restrictive dieting or consistently eating too few calories can also affect hair growth.

Depending on your symptoms and medical history, your provider may consider evaluating nutritional markers such as iron status and other nutrients.

Instead of randomly taking multiple “hair growth” supplements, identifying an actual deficiency allows treatment to be much more targeted.

Our approach can combine laboratory evaluation with individualized nutrition guidance to help identify and address nutritional gaps.

4. Not Eating Enough Protein

Hair is primarily composed of a protein called keratin.

If you’re consistently under-eating protein—or dramatically restricting calories—your body may not have the nutritional resources it needs to optimally support hair growth.

This can be particularly important during weight loss.

Healthy weight loss shouldn’t mean starving your body.

At Pro Health Functional Medicine, our weight-management approach incorporates nutrition and exercise guidance alongside medical care because protecting muscle, nutritional status, metabolic health, and overall wellness matters just as much as the number on the scale.

5. Rapid Weight Loss

Have you recently lost a significant amount of weight?

Major or rapid weight loss can act as a physiological stressor and may trigger a temporary type of excessive shedding known as telogen effluvium.

Interestingly, the shedding may not happen immediately. It can appear several months after the triggering event.

This is another reason sustainable weight management and adequate nutrition are so important.

6. Physical or Emotional Stress

Hair can sometimes tell the story of what happened to your body several months ago.

A significant stressor can push more hairs than usual into the resting phase of the hair-growth cycle.

Possible triggers include:

• Significant illness

• High fever

• Surgery

• Major emotional stress

• Childbirth

• Rapid weight loss

• Significant changes in health

  
  

The resulting shedding can occur months after the original event, making the connection easy to miss.

7. Insulin Resistance and Metabolic Health

Metabolic and hormonal health are interconnected.

Conditions associated with insulin resistance—particularly PCOS—can occur alongside hormonal changes that affect hair growth.

If hair thinning occurs along with symptoms such as increasing abdominal weight, irregular periods, acne, excess facial hair, difficulty managing weight, or blood-sugar concerns, a broader metabolic and hormonal evaluation may be appropriate.

At Pro Health, we can evaluate metabolic health through medical history, laboratory testing, nutrition, and individualized treatment when indicated.

8. Autoimmune Conditions

Sometimes hair loss involves the immune system.

Alopecia areata, for example, is an autoimmune condition in which the immune system attacks hair follicles and often produces distinct patches of hair loss.

Other autoimmune or inflammatory conditions can also affect hair.

Sudden, patchy, rapidly progressing, painful, inflamed, or scarring hair loss deserves medical evaluation. A dermatologist is often an important part of diagnosing these types of hair loss.

9. Medications and Supplements

Hair loss can also be a side effect of certain medications.

If your hair loss began after starting or changing a medication, bring that timeline to your healthcare provider’s attention.

Don’t discontinue a prescription medication on your own because you suspect it is affecting your hair. Your provider can help determine whether the medication could be contributing and whether alternatives should be considered.

And more supplements aren’t necessarily better.

Taking excessive amounts of certain nutrients can actually contribute to hair loss, which is another reason we prefer testing and individualized recommendations over guessing.

10. Genetics and Female or Male Pattern Hair Loss

Sometimes the underlying cause is genetic.

Androgenetic alopecia—often called male-pattern or female-pattern hair loss—is the most common form of hereditary hair loss.

Women often notice a widening part or progressive thinning over the top of the scalp, while men commonly develop a receding hairline or thinning at the crown.

Early identification matters because some forms of progressive hair loss respond better when treatment begins sooner.

A dermatologist can help distinguish pattern hair loss from other conditions that may look similar.

Hair Shedding vs. Hair Thinning: What’s the Difference?

These aren’t necessarily the same thing.

Hair shedding often means you’re suddenly losing more hairs than usual. You may notice large amounts in the shower, brush, sink, or on your clothing.

Hair thinning tends to be more gradual. Your individual hairs may become finer, your overall density decreases, or your scalp becomes increasingly visible.

Understanding which pattern you’re experiencing can provide valuable clues about the underlying cause.

What Labs Can Be Checked for Hair Loss?

There isn’t one universal “hair loss panel.”

Testing should be based on your symptoms, health history, medications, diet, age, and pattern of hair loss.

Depending on the individual, a healthcare provider may consider evaluating areas such as:

• Thyroid function

• Iron status

• Blood count

• Nutritional status

• Hormones when clinically appropriate

• Blood sugar and metabolic health

• Other testing based on symptoms and medical history

The goal isn’t to order every possible lab. It’s to order the right labs for the right person.

How Pro Health Functional Medicine Can Help

When appropriate, our approach to unexplained hair thinning looks beyond the hair itself.

Depending on your individual situation, care at Pro Health Functional Medicine may include:

Comprehensive Lab Testing

We can investigate potential contributors such as thyroid function, iron status, nutritional deficiencies, metabolic health, and other relevant markers.

Hormone Evaluation & HRT

For appropriate patients experiencing perimenopause, menopause, or other hormonal concerns, we can evaluate hormone health and discuss treatment options when medically indicated.

Thyroid Evaluation

Hair loss combined with fatigue, weight changes, cold intolerance, constipation, or other symptoms may warrant a closer look at thyroid health.

Nutrition Support

Our nutrition services can help ensure you’re getting adequate protein, calories, vitamins, minerals, and nutrient-dense foods to support overall health.

Metabolic & Weight Management

If insulin resistance, metabolic health, or significant weight changes may be contributing, we can evaluate the bigger metabolic picture rather than focusing solely on the hair.

Personalized Medical Care

There is no single hair-loss protocol that’s appropriate for everyone. Treatment should be based on the underlying diagnosis.

And when the pattern suggests a dermatologic condition, we may recommend evaluation by a dermatologist rather than trying to treat something outside the appropriate scope of care.

When Should You See a Healthcare Provider About Hair Loss?

Consider scheduling an evaluation if you’re experiencing:

• Sudden or excessive shedding

• Noticeably widening part

• Significant loss of hair density

• Circular or patchy bald spots

• Hair loss accompanied by fatigue or unexplained weight changes

• Scalp redness, scaling, pain, or inflammation

• Loss of eyebrows or eyelashes

• Hair loss that continues for several months

• Hair changes alongside symptoms of hormonal or thyroid dysfunction

  
  

Sudden, patchy, painful, inflamed, or scarring hair loss should be evaluated promptly.

Don’t Just Treat the Hair—Investigate the Why

Hair thinning can be frustrating, but it can also provide information about what’s happening elsewhere in the body.

Sometimes the answer is genetics.

Sometimes it’s a temporary response to illness or stress.

And sometimes hair loss is one piece of a larger picture involving thyroid health, hormones, nutrition, metabolism, or another medical condition.

If you’ve been wondering “Why is my hair thinning?”, it may be time to stop guessing.

At Pro Health Functional Medicine in Chandler, Arizona, we help patients take a comprehensive look at their health and identify potential contributors to symptoms through individualized medical care, laboratory testing, nutrition, and treatment when appropriate.

Your hair may be the symptom. Understanding the cause is where the conversation should begin.

Contact Pro Health Functional Medicine to schedule a consultation and learn whether a more comprehensive evaluation may be right for you.