What Causes Hair Loss? Genetics, DHT, Hormones, and Everything Else Behind Thinning Hair

Q: Is hair loss genetic or hereditary?

Genetics play a major role in hair loss for both men and women. A family history of thinning or baldness raises the odds of experiencing similar patterns, though hormones and lifestyle factors influence how early and how severely hair loss develops.

Q: What role does DHT play in hair loss?

DHT (dihydrotestosterone) shrinks hair follicles over time in people who carry genetic sensitivity to this hormone. Smaller follicles produce thinner, shorter hair strands until growth stops altogether in affected areas.

Q: Can stress cause hair loss?

High or prolonged stress pushes hair follicles into a resting phase early, leading to a condition called telogen effluvium. Shedding usually appears two to three months after the stressful event and improves once stress levels drop.

Q: Do vitamin deficiencies cause hair thinning?

Low levels of iron, vitamin D, zinc, and biotin weaken hair growth cycles and contribute to shedding. Correcting a deficiency through diet or supplements often restores normal growth within a few months.

Q: Is hair loss reversible?

Reversibility depends on the cause and how long follicles stayed inactive. Hair loss from stress, deficiencies, or early hormonal changes often responds well to treatment, while long-dormant follicles from advanced genetic hair loss are harder to revive.

Q: What treatments target the root cause of hair loss?

PRP therapy and GFC stimulate follicle activity directly, while addressing hormonal imbalance, nutritional gaps, or stress treats the underlying trigger. A personalized evaluation identifies which combination fits the specific cause.

Emilio Duran

Sep 3

6 min read

Executive Summary:

Hair loss can stem from genetic factors and hormonal changes, illness, medications, nutritional issues, autoimmune conditions, and hair-care practices. Some forms involve follicle miniaturization, while others cause temporary shedding or patchy loss. Identifying the underlying cause is an important first step toward choosing appropriate treatment.

What Causes Hair Loss?

Hair doesn't just fall out for no reason. Something is always driving it: your DNA, a hormone shift, or something building quietly beneath the scalp. The tricky part is that hair loss rarely announces itself with one clear cause. It shows up as a tangle of genetics, hormones, and habits all pulling in the same direction. Maybe you've noticed a wider part or a hairline that looks different in photos.

That gap between what you see and what you expected can feel unsettling at first. Once you understand what's actually happening beneath the surface, the mystery starts to disappear, along with the feeling that you're fighting something you can't see.

What Triggers Hair Thinning in the First Place?

Every strand cycles through phases of growth, rest, and shedding. Under normal conditions, this cycle stays balanced. Hair thinning can occur when the normal growth cycle is disrupted, when more follicles enter the shedding phase, or when follicles gradually miniaturize. The underlying mechanism depends on the type of hair loss. Genetics, hormones, inflammation, and nutrition can all push that cycle out of balance, which is why two people with thinning hair can have completely different underlying causes.

The Hair Growth Cycle in Simple Terms

Hormonal changes, illness, medications, nutritional deficiencies, and significant physical or emotional stress can disrupt the hair growth cycle and increase shedding. One of the most common hormonal hair loss causes behind a shift toward telogen is a drop in estrogen or a change in thyroid output.

Is Hair Loss Genetic? The Truth About Inherited Baldness

Genetics plays an important role in pattern hair loss, and inheritance is more complicated than the old myth about it coming only from your mother's side. Genetic hair loss involves multiple genes, not a single inherited trait.

How Genetics Affects Both Men and Women

The androgen receptor gene sits on the X chromosome and is inherited from the mother, but researchers have identified other genes linked to pattern hair loss that can be influenced by genes from either parent. A family history on either side can increase the likelihood of developing pattern hair loss.

DHT and Hair Loss: The Hormone Behind Pattern Baldness

Dihydrotestosterone, or DHT, is a hormone made when testosterone is converted by 5-alpha reductase. DHT plays an important role in androgenetic alopecia, where genetically susceptible follicles can gradually become smaller and produce finer hairs. Research also suggests that the response to androgens depends on the individual follicle and genetic background. However, DHT does not explain every form of hair loss, and its role in female pattern hair loss is more complex than in male pattern hair loss.

Not every follicle responds to DHT the same way. Genetic differences in follicular sensitivity help explain why some follicles are more susceptible to pattern hair loss than others.

Hormonal Hair Loss Causes Beyond DHT

DHT gets most of the attention, but it isn't the only hormonal driver. Thyroid disorders can contribute to diffuse hair thinning or increased shedding. Hair often improves once the underlying thyroid condition and hormone levels are properly managed.

Hormonal changes around menopause can coincide with or contribute to increased hair thinning, particularly in women already predisposed to female pattern hair loss. Pregnancy often thickens hair temporarily, followed by postpartum shedding once hormone levels drop. PCOS can involve elevated androgen levels and is associated with female pattern hair loss in some women.

Other Factors That Contribute to Thinning Hair

Genetics and hormones explain most cases, but several reversible factors deserve attention. Understanding what triggers hair thinning beyond genetics and hormones helps rule out causes that are often easier to fix.

● Significant physical or emotional stress can lead to telogen effluvium, a temporary increase in shedding.

● Nutritional deficiencies, including inadequate iron, protein, zinc, or biotin, can contribute to noticeable hair loss.

● Autoimmune activity causes alopecia areata, where the immune system attacks follicles.

● Certain medications list hair thinning as a known side effect.

● Tight hairstyles can cause traction alopecia, while excessive heat styling can weaken the hair shaft and cause breakage.

Comparing the Major Causes of Hair Loss

Cause	How It Affects Hair	Who It Typically Affects	Reversible?
Genetics (AGA)	Causes progressive follicle miniaturization in genetically susceptible follicles	Men and women with a genetic predisposition	Treatment can slow progression and may improve growth
DHT sensitivity	Androgen signaling contributes to follicle miniaturization in androgenetic alopecia	Genetically susceptible individuals	Often manageable with appropriate treatment
Thyroid imbalance	Can contribute to diffuse hair thinning or increased shedding	People with thyroid disorders	Hair may regrow after the underlying problem is treated
Telogen effluvium	Causes increased shedding after a physical or emotional stressor	People following illness, major stress, weight loss, surgery, or other triggers	Usually temporary and reversible
Alopecia areata	Immune activity attacks hair follicles, causing patchy or diffuse loss	People of any age or sex	Variable; regrowth is possible
Nutritional deficiency	Inadequate nutrients can contribute to increased shedding and impaired hair growth	People with inadequate intake or absorption problems	Often improves after the deficiency is corrected
Traction alopecia	Repeated or prolonged tension damages hair follicles	People who frequently wear tight hairstyles or extensions	Often improves if addressed early; prolonged damage can become permanent

The table above covers most cases of genetic hair loss in both men and women, along with reversible factors that often get overlooked.

Table Source: American Academy of Dermatology

Emerging Research: What's New in Understanding Hair Loss

Hair loss science has moved beyond a single-hormone explanation. Recent laboratory work has mapped additional molecular pathways involved in follicle miniaturization, independent of the classic DHT hair loss causes doctors have relied on for decades.

A 2025 scoping review covering PRP, photobiomodulation, stem cells, and exosomes noted that androgenetic alopecia affects up to half of all adults, driving interest in therapies that work with the body's own repair signals. Exosome therapy is one of the most closely watched developments in hair growth. A systematic review of clinical studies through 2025 found exosome-based treatments showed improvements in hair density and thickness, with a favorable safety profile, though the evidence base is still growing.

Curious how these regenerative advances could apply to you? Dr. Jay Goldstein stays current on the latest exosome therapy for hair regrowth research and can give you an honest read on your case, pointing you toward this option or a more established one if that makes more sense right now.

Why Identifying the Root Cause Changes Everything

Two people can lose hair for entirely different reasons and need different treatment plans. Someone with thyroid-related hair loss may need evaluation and treatment for the underlying thyroid disorder rather than treatment aimed specifically at androgenetic alopecia. Figuring out why does hair loss happen in your specific case matters more than following generic advice, since applying the wrong treatment wastes time follicles don't have to spare.

An evaluation may include a scalp examination and medical and family history. Depending on the symptoms and potential cause, a clinician may also recommend blood tests to look for conditions such as thyroid dysfunction or nutritional deficiencies. From there, a plan can target the actual mechanism driving your hair loss.

Frequently Asked Questions

Is hair loss genetic or hereditary?

Yes, pattern hair loss is strongly influenced by genetics and can involve multiple genes inherited from either side of the family.

What role does DHT play in hair loss?

DHT plays an important role in androgenetic alopecia. In genetically susceptible follicles, androgen activity can contribute to follicle miniaturization and the production of progressively finer hairs. Its role in female pattern hair loss is less clearly established than in male pattern hair loss.

Can stress cause hair loss?

Yes, major physical or emotional stress can contribute to telogen effluvium, which causes temporary increased shedding.

Do vitamin deficiencies cause hair thinning?

Certain nutritional deficiencies, particularly iron deficiency, can contribute to hair shedding or thinning. Treatment depends on whether a deficiency is actually present.

Is hair loss reversible?

Reversibility depends on the cause. Some temporary forms of shedding improve after the underlying trigger resolves, while hereditary hair loss is usually managed rather than completely reversed. Early treatment can help preserve existing hair and may improve density in some people.

What treatments target the root cause of hair loss?

Treatment depends on the diagnosis. Hereditary hair loss may be treated with options such as minoxidil and, in appropriate patients, certain prescription medications. Other causes require treatment directed at the underlying condition.

Final Thoughts

Hair loss rarely comes down to one cause. Genetics can influence susceptibility to pattern hair loss, while hormones, illness, medications, nutritional deficiencies, autoimmune conditions, and hair-care practices can contribute to other forms of shedding or thinning. Understanding which factors apply to you can make it easier to choose an appropriate treatment.

Ready to find out what's actually driving your hair loss? Ask Dr. Jay Goldstein about growth factor concentrate treatment, along with other regenerative options built around your specific diagnosis.