What Causes Hair Loss Besides Genetics? 10 Common Factors to Consider

While androgenetic alopecia (male pattern baldness) remains the most common cause of hair loss in men, it’s far from the only factor. Many non-genetic triggers can disrupt the hair growth cycle, weaken follicles, or inflame the scalp. Understanding these contributors is essential for proper diagnosis and an effective treatment strategy.Below we cover 10 factors that contribute to hair loss by answering the most common questions related to each.

1. Stress-Induced Hair Loss (Telogen Effluvium)

Severe physical or emotional stress can push a disproportionate number of hair follicles into the telogen (resting) phase. This condition, known as telogen effluvium, often appears two to three months after a triggering event such as surgery, illness, a breakup, or job loss.

Can stress really cause hair loss in males?

Yes, stress can significantly disrupt the normal hair growth cycle. This effect is especially pronounced during periods of acute stress such as hospitalization, surgery, high fever, physical trauma, or the sudden loss of a loved one.

Chronic stress, on the other hand, can have a more subtle but sustained impact by elevating cortisol levels over time. Prolonged high cortisol disrupts hormone balance and nutrient uptake, which can continuously impair the hair growth cycle, leading not just to shedding but also to weaker, thinner hair strands.

In either case, the extent of hair loss usually reflects both the severity and the duration of the stressor. It's important to note that addressing stress proactively through lifestyle changes, counseling, or medical support can help restore proper hair cycling and promote recovery.

How long does stress-related hair loss last?

Typically, it lasts about 3 to 6 months. Most individuals notice increased shedding begins two to three months after a major stressful event, such as surgery, illness, or intense emotional distress. This is because hair follicles prematurely enter the telogen (resting) phase in response to the stressor, leading to noticeable thinning or more hair in the shower, on your pillow, or when brushing.

Once the source of stress is removed or effectively managed, the body gradually restores balance, and hair follicles slowly return to their normal growth (anagen) phase. As new hairs begin to grow, overall shedding decreases and regrowth becomes more apparent. In most cases, full recovery is possible, but the speed of regrowth can vary depending on the duration and severity of the stress, as well as individual health factors such as age, nutrition, and underlying medical conditions.

Is stress-induced hair loss reversible?

Yes, telogen effluvium is usually self-limiting and reversible, provided the underlying cause is managed. When stress levels are reduced and the triggering event has passed, the hair cycle gradually normalizes, and new hair growth resumes. Most people experience full regrowth of lost hair, although this process can take several months.

In rare cases, if stressors persist or if there are additional contributing factors (like poor nutrition or ongoing medical issues), recovery may be slower. Supportive care—including gentle hair practices, proper diet, and stress management techniques—can promote healing and accelerate restoration.

Further Reading: American Osteopathic College of Dermatology, “Telogen Effluvium Hair Loss”

2. Hormonal Imbalances (Thyroid, DHT, Testosterone)

Even without a genetic predisposition, hormonal fluctuations can disrupt hair health. Elevated DHT (dihydrotestosterone; a byproduct of testosterone) levels can miniaturize follicles, while thyroid disorders (both hypo- and hyperthyroidism) can lead to excessive shedding.

How do hormones affect hair loss aside from genetics?

Hormones regulate the hair cycle in several important ways, influencing growth, shedding, and overall hair health. Androgens like DHT (dihydrotestosterone) are especially impactful: they shorten the anagen (growth) phase and miniaturize hair follicles, ultimately leading to thinner, weaker hair—even in men who lack a genetic tendency for balding. Elevated DHT levels may cause hair follicles to shrink prematurely, producing shorter, finer hairs or causing them to stop growing altogether.

Other hormonal fluctuations can play a role as well—for example, changes in testosterone, cortisol (the stress hormone), or even fluctuations related to aging or medications. These shifts can disrupt the timing of follicle cycling or the supply of nutrients to the scalp, further impacting hair shaft integrity and density. Managing underlying hormonal imbalances is often key to restoring healthy hair growth.

Can thyroid issues cause hair loss in men?

Yes. Both overactive (hyperthyroidism) and underactive (hypothyroidism) thyroid conditions can cause noticeable hair loss in men. These imbalances disrupt the normal hair growth cycle, often resulting in diffuse thinning across the scalp rather than in distinct patches.

The follicles may enter a resting phase prematurely or shed more than usual, making overall hair appear thinner. Addressing the underlying thyroid disorder—typically through medication, dietary changes, or hormone therapy—often helps stabilize or significantly reduce hair loss. In many cases, once thyroid levels are controlled, hair regrowth is possible over several months, though the timeline can vary based on the severity and how long the imbalance persisted.

3. Nutrient Deficiencies

Essential nutrients for hair include iron, vitamin D, biotin, zinc, and protein. Deficiencies can stem from poor diet, restrictive eating, malabsorption, or underlying conditions.

Which vitamin or mineral deficiencies cause hair loss in men?

Iron deficiency is particularly linked to telogen effluvium—a form of hair shedding where more follicles than usual enter the resting phase and fall out. Iron is vital for oxygen transport to hair follicles; when levels drop, the follicles become deprived of nutrients and may cease functioning properly.

In addition to iron, low levels of vitamin D have also been associated with increased hair shedding and slower regrowth, since vitamin D helps create new hair follicles and supports immune health. Biotin (vitamin B7) deficiency can weaken the hair shaft, making strands more prone to breakage and thinning; biotin also plays a critical role in the production of keratin, the main protein that constitutes hair.

Zinc is another essential mineral, as it aids in follicle repair and growth—zinc deficiency can disrupt normal hair cycling and result in hair loss, dryness, or brittleness.

Can a lack of protein cause hair loss?

Yes. Hair is primarily composed of keratin, a structural protein, which gives each strand its strength and resilience. When the body experiences severe protein deficiency—such as during crash dieting, prolonged fasting, malnutrition, or certain health conditions—it prioritizes essential organs and vital functions over hair production. As a result, the scalp receives fewer building blocks necessary for healthy follicles, and the body shifts hair follicles from the growth (anagen) phase into the resting (telogen) phase prematurely. This leads to increased shedding and noticeable thinning of hair. Over time, hair may become weaker, more brittle, and regrow at a much slower rate.

The impact of protein deficiency can be especially pronounced for individuals who suddenly reduce their protein intake, such as those on restrictive or fad diets, vegetarians or vegans without proper dietary planning, or those recovering from illness. Fortunately, once adequate protein levels are restored in the diet, hair growth often resumes within several months, though full density can take time to recover. Including a variety of protein-rich foods, such as lean meats, fish, eggs, dairy, legumes, nuts, and seeds, is essential to support strong hair structure and minimize the risk of deficiency-related shedding.

4. Medication Side Effects

Several medications list hair loss as a known side effect, including chemotherapy agents, beta-blockers, antidepressants, and retinoids.

What medications are known to lead to hair loss in males?

Chemotherapy causes anagen effluvium, which is a rapid and often dramatic form of hair loss that occurs when drugs target rapidly dividing cells, including those in hair follicles. This kind of hair loss is typically seen within days to weeks of starting treatment and often includes loss of not only scalp hair but also eyebrows, eyelashes, and body hair.

Beyond chemotherapy, a variety of commonly prescribed drugs can trigger telogen effluvium, a condition where more hairs than normal enter the shedding (telogen) phase. These include beta-blockers (used to treat high blood pressure), isotretinoin (a medication for severe acne), anticonvulsants (for seizure disorders), selective serotonin reuptake inhibitors (SSRIs, which are antidepressants), and others such as anticoagulants (blood thinners), retinoids, and some cholesterol-lowering agents.

The degree and speed of hair loss can vary significantly depending on a person’s sensitivity, the specific medication, its dosage, and how long it’s taken. Some people may only experience mild thinning, while others could notice more pronounced shedding or even patchy loss.

Is medication-related hair loss permanent?

Usually not. In most cases, hair often regrows within a few months after stopping the medication that triggered the shedding. The hair follicles are generally not permanently damaged—instead, the medication temporarily disrupts the natural hair growth cycle, leading to excessive shedding, which is usually reversible once the offending drug is discontinued. Hair typically begins to regrow as follicles re-enter the growth (anagen) phase, although full restoration of density may take several months.

However, there are exceptions. Prolonged or high-dose use of certain medications can cause more persistent shedding, and rarely, some drugs may trigger scarring (cicatricial) alopecia, where the hair follicle becomes permanently damaged and cannot regenerate. These situations are uncommon, and most people regain their hair with time and proper medical support.

5. Autoimmune Conditions (Alopecia Areata)

Alopecia areata is an autoimmune disease where the body attacks its own hair follicles, causing patchy hair loss. It can be triggered by stress, infections, or genetic predisposition.

Are autoimmune diseases a major factor in male hair loss?

Less common than genetic or stress-related causes, but highly impactful when present. In autoimmune conditions such as alopecia areata, the body's immune system mistakenly targets hair follicles as if they were foreign invaders, disrupting the normal growth cycle and triggering rapid hair shedding. The immune response can be sudden and aggressive, leading to patchy bald spots or, in some cases, widespread hair loss over a very short period.

Autoimmune-related hair loss can be unpredictable—flare-ups may develop unexpectedly, and the severity can vary from small, isolated patches to complete loss of scalp or body hair. Because autoimmune hair loss is rooted in immune system dysfunction, it often requires specialized treatment such as corticosteroid injections, immunotherapy, or other medications designed to suppress the immune attack and encourage regrowth. Early intervention and medical guidance are critical, as successful management can greatly improve the chances for hair recovery and reduce recurrence.

What does alopecia areata look like in men?

Typically, alopecia areata presents as smooth, round, or oval bald patches on the scalp or beard area. The affected skin is usually normal in texture, appearing soft and unscarred, without flaking, scaling, redness, or inflammation. These bald patches can range from small coin-sized areas to larger zones of hair loss, and sometimes multiple spots may merge to form more extensive patches. In some cases, short, broken hairs called “exclamation point” hairs are seen at the edge of the bald areas—these grow narrower closer to the scalp. While the scalp is the most common site, alopecia areata can also affect the beard, eyebrows, eyelashes, and, occasionally, other parts of the body. Despite the dramatic appearance, the underlying skin remains healthy, which sets alopecia areata apart from other scalp conditions that may cause scarring or noticeable irritation. Hair regrowth is possible, though new hair may initially appear fine or lighter in color before thickening and returning to its typical shade over time.

Source: National Alopecia Areata Foundation, “Understanding Alopecia Areata”

6. Fungal and Bacterial Infections

Conditions like tinea capitis, folliculitis, and seborrheic dermatitis can inflame the scalp and damage follicles.

Can infections really lead to hair loss?

Yes. Infections disrupt the follicular environment and can lead to temporary or permanent hair loss, depending on the extent of inflammation and scarring. Fungal infections like tinea capitis invade the scalp, damaging the hair shaft and root, and often causing scaly, itchy patches where the hair breaks off or falls out in clumps. Bacterial infections, such as folliculitis, trigger localized inflammation and pus-filled bumps that can weaken or destroy hair follicles.

If the infection is superficial and treated promptly, hair usually regrows once the scalp heals. However, if the inflammation is severe or lingers untreated, the resulting damage can scar the follicles, making hair loss permanent in affected areas. Some chronic scalp conditions, like seborrheic dermatitis, can also foster an environment that impairs healthy follicle function over time, further contributing to ongoing shedding or thinning. Identifying and addressing infections early, with antifungal, antibacterial, or anti-inflammatory treatments, greatly increases the likelihood of full recovery and reduces the risk of long-term hair loss.

What are signs of a scalp infection causing hair loss?

Look for redness, swelling, scaling, itchiness, pustules, or oozing on the scalp—these are common signs of infection that can compromise hair follicle health. Affected areas may feel tender or sore to the touch, and in some cases, clusters of small bumps or sores (often filled with pus) may be visible. Tinea capitis, a common fungal infection, typically causes broken hairs and the appearance of black dots where strands have snapped off at the scalp's surface. Some infections lead to distinct, ring-like patterns of hair loss or patches of thinner hair surrounded by inflamed or crusted skin.

7. Poor Diet and Crash Dieting

Severe calorie restriction, especially without adequate protein, can lead to temporary hair shedding.

How does diet impact male pattern hair loss?

While it may not cause androgenetic alopecia, a poor diet can worsen existing hair loss and delay regrowth by depriving follicles of essential nutrients. Crash dieting or restrictive eating patterns can trigger sudden hair loss episodes (telogen effluvium) and slow the return to normal density once the underlying trigger is resolved. Even for those genetically predisposed to male pattern baldness, eating a balanced, nutrient-rich diet supports overall follicle health and may help maximize the quality, strength, and longevity of remaining hair.

Can crash dieting cause temporary hair loss?

Yes. Sudden calorie drops create metabolic stress that triggers telogen effluvium, a condition where large numbers of hair follicles prematurely enter the resting (telogen) phase and shed several weeks to months later. Because hair is a non-essential tissue, the body conserves nutrients during times of nutritional scarcity by diverting proteins, vitamins, and minerals away from hair growth and toward vital organs. The result can be noticeable thinning or excessive shedding, usually appearing 2-3 months after restrictive dieting begins.

Fortunately, this type of hair loss is usually not permanent—once regular eating patterns and adequate nutrition are restored, hair follicles gradually resume their normal growth cycle. Most people see new hair growth and a return to previous density within 3-6 months of nutritional recovery, although the timeline can vary depending on how long and how severely the body was deprived of nutrients. For optimal hair recovery, it’s important to reintroduce a balanced diet rich in protein, iron, zinc, vitamins, and healthy fats, and to avoid frequent or extreme dieting that disrupts the hair cycle.

8. Environmental Factors and Pollution

Pollutants, toxins, and even hard water can cause oxidative stress, inflammation, and follicular damage.

How does environmental pollution influence male scalp and hair health?

It disrupts the scalp microbiome, increases oxidative damage, and impairs circulation to follicles, contributing to thinning over time. Pollutants such as heavy metals, particulate matter, and toxic chemicals present in the air can settle onto the scalp and hair, causing direct irritation and triggering inflammatory responses within the skin. This exposure undermines the delicate microbial balance of the scalp, sometimes leading to itchiness, dandruff, or excess oil production—all of which further weaken follicles.

Can air pollution really lead to hair loss?

Pollutants can penetrate the scalp and damage follicular cells at the molecular level. Fine dust, soot, smoke, and toxic chemicals suspended in the air can cling to hair strands and the scalp, leading to repeated irritation, inflammation, and an unstable scalp environment. Over time, these pollutants create oxidative stress, which harms the structural proteins and lipids that fortify hair and maintain healthy follicle function. Research has shown that exposure to air pollution not only weakens individual hairs—making them more difficult to grow and easier to break—but also disrupts the normal hair growth cycle by shortening the growth phase and triggering premature entry into the shedding phase.

Men who live in industrial cities or near high-traffic areas are at enhanced risk, and the cumulative effects may appear as gradual thinning, increased breakage, and sometimes even localized bald spots, especially if scalp cleansing and protective care are neglected. To reduce risk, it’s important to regularly wash the scalp, use antioxidant-rich shampoos or scalp serums, and take steps—like covering the head in polluted environments—to minimize ongoing exposure.

9. Traction Alopecia from Grooming Habits

Consistent tension from hairstyles, helmets, or aggressive brushing can cause traction alopecia, a form of mechanical hair loss.

What is traction alopecia? Can grooming habits cause long-term hair damage?

A preventable form of hair loss caused by chronic pulling on the follicles. This commonly results from tight hairstyles—such as braids, ponytails, man buns, cornrows, dreadlocks—or repeated use of hair extensions, helmets, or headbands that put ongoing stress on the same areas of the scalp. Over weeks, months, or years, this tension weakens the follicle anchors, leading to gradual thinning around the frontal hairline, temples, or wherever the tension is greatest. Early signs may appear as broken or receding hair near the edges, followed by patchy bald spots if the cause is not addressed.

If the tension continues, the constant inflammation can damage the follicles permanently and lead to scarring (cicatricial alopecia). At this stage, hair loss becomes irreversible because the follicles are replaced by scar tissue. However, when identified early and the traction is relieved, hair usually regrows over several months. Preventing traction alopecia involves choosing looser hairstyles, alternating how hair is worn, and being gentle while brushing or styling.

10. Chronic Illness or Major Surgery

Hair loss may occur after systemic illness or surgery due to physiological stress or inflammatory responses.

Can illness or surgery trigger hair loss in men?

Yes. The body diverts energy from hair production to recovery. Serious illnesses, major surgeries, prolonged fevers, infections, and even hospitalization can all act as significant stressors to the system. When faced with physiological stress, the body shifts its resources toward essential organs and healing processes, deprioritizing less critical functions like hair growth. This systemic shock often forces many hair follicles into the resting (telogen) phase, resulting in noticeable shedding—sometimes called telogen effluvium.

Anesthesia, blood loss, changes in medications, and the physical stress of surgery itself can further exacerbate the risk, especially if recovery is prolonged or complicated by additional health issues. Most stress-related hair loss of this type appears a few months after the triggering event and tends to resolve on its own as the body returns to normal and healing is complete. Prompt nutritional support, rest, and effective management of underlying medical issues can help expedite regrowth and reduce overall hair loss.

Is post-surgery hair loss temporary?

Usually, yes. Most cases of hair shedding after surgery—known as telogen effluvium—are self-limited and resolve naturally within 6 to 9 months once the body returns to its baseline health. As your body recovers from the physiological stress of anesthesia, blood loss, and the healing process, normal hair growth resumes and any excessive shedding gradually subsides. During this regrowth phase, you may notice new, fine hairs sprouting in affected areas, eventually thickening over time.

However, the speed of recovery can be influenced by several factors. Older adults or individuals with compromised immune systems may experience a slower return to full hair density, and recovery could be further delayed if there are ongoing complications, additional illnesses, or continued nutritional deficiencies. Ensuring good postoperative care, balanced nutrition, and effective management of stress and underlying conditions can help support the hair’s return to normal.

Wrap Up

While genetics is a major player, it’s only one piece of the hair loss puzzle. Non-genetic factors can significantly contribute to hair thinning and shedding. The good news? Many of these causes are identifiable and treatable. If you’re experiencing hair loss, consult with a professional at Flycatcher for a personalized diagnosis and plan. Early intervention can make a world of difference. You can schedule a consultation here or download our Hair Restoration Information Packet.

Flycatcher is conveniently located in Spicewood, Texas – just three miles west of The Galleria in Bee Cave. We’re proud to serve Spicewood, Bee Cave, Lakeway, and the surrounding areas of Austin and the Texas Hill Country. Call or shoot us a text at (737) 239-0112 today.