What Causes Hair Loss in Men? Genes, Shedding and Other Causes
What causes hair loss in men: inherited pattern loss, stress shedding, illness, medicines, thyroid and low iron. How each looks and which ones regrow.
By Julian Caraulani · Last updated
TreatmentReviewed by Dr. A. Goher, MBBS
- FDA-approved and compounded
- LegitScript seal ID shown
- No state list published
Finding the cause matters, because each one is handled differently. This page walks through the main causes of hair loss in men, how each one looks, and which ones regrow without help. Only pattern hair loss needs the drugs our price tables cover. We do not diagnose. A dermatologist can.
Causes of hair loss: the main list
| Cause | How it usually looks | Regrows on its own? |
|---|---|---|
| Male pattern hair loss (genes) | Receding temples, thinning crown, over years | No: treatment can slow or partly reverse it |
| Shedding after stress, illness or weight loss | Thinning all over, a few months after the event | Usually, within months |
| Age | Slow thinning and greying | No |
| Alopecia areata (immune) | Round, smooth bald patches | Often |
| Medicines and cancer treatment | Thinning or loss after starting a drug | Often, after the cause stops |
| Thyroid disease | Thinning hair, sometimes in clumps | Yes, once treated |
| Low iron, protein, zinc or biotin | Noticeable thinning | Yes, once corrected |
| Scalp infection or psoriasis | Scaly patches, broken hairs | Usually, once treated |
| Tight hairstyles or hair pulling | Loss at the hairline or in patches | Only if the root survives |
| Scarring alopecia | Smooth, shiny patches | No |
All rows come from the AAD's list of causes, read 14 Nov 2026.
What causes balding: male pattern hair loss
Pattern hair loss runs in families. The AAD says it means "you've inherited genes that cause your hair follicles (what each hair grows out of) to shrink and eventually stop growing hair" (AAD).
The driver is a hormone called DHT, which the body makes from testosterone. MedlinePlus, the US National Library of Medicine's health site, says it is "related to hormones called androgens, specifically an androgen called dihydrotestosterone (DHT)" (MedlinePlus: androgenetic alopecia, read 14 Nov 2026). Androgens are male hormones. Androgenetic alopecia is the medical name for male pattern hair loss.
MedlinePlus describes the pattern. Hair loss begins "above both temples". Over time, "the hairline moves back (recedes) to form a characteristic M shape." Hair also thins at the crown. It is common: "more than 50 percent of men over age 50 have some degree of hair loss."
This is the one cause that does not stop by itself. The AAD says, "Without treatment, you will continue to lose hair." It also says, "The earlier treatment is started, the better it works."
- FDA-approved and compounded
- LegitScript seal ID shown
- No state list published
Why is my hair falling out all at once?
Sudden, heavy shedding is usually a different problem. It is called telogen effluvium. The AAD says, "It's normal to shed between 50 and 100 hairs a day" (AAD: hair loss or hair shedding?, read 14 Nov 2026). Shedding far more than that is excess shedding.
The AAD lists common triggers. They include having "Lost 20 pounds or more", "Experiencing lots of stress", a high fever, or having "Undergone an operation". The timing is the clue: "Most people notice the excessive hair shedding a few months after the stressful event."
This kind usually fixes itself. The AAD says, "As your body readjusts, the excessive shedding stops." Hair tends to regain its fullness within six to nine months. Our guide to telogen effluvium vs male pattern baldness shows how to tell the two apart. Weight loss drugs are a common modern trigger, covered in our GLP-1 hair loss guide.
What causes thinning hair besides genes
Several health problems can thin hair. Each one usually improves once it is treated.
- Thyroid disease. The AAD says, "If you have a problem with your thyroid, you may see thinning hair." Treating the thyroid can reverse it.
- Low nutrients. "If you're not getting enough of one or more of these, you can have noticeable hair loss," the AAD says of biotin, iron, protein and zinc. A blood test can check.
- Too much of some supplements. The AAD warns that "Taking large amounts of vitamin A or selenium is also toxic and can cause hair loss."
- Medicines. The AAD says hair loss is "A possible side effect of some medications." It warns not to stop a medicine before talking with your doctor.
- Alopecia areata. This is an immune problem that causes round bald patches. It can affect the beard and eyebrows too.
- Scalp infections and psoriasis. These cause scaly patches and broken hairs. Hair tends to regrow once they clear.
Hair care and hairstyles
How you treat your hair can matter too. The AAD says that if you "often wear your hair tightly pulled back, the continual pulling can lead to permanent hair loss." This is called traction alopecia. Harsh dyes and relaxers can damage hair over time.
Some common worries are not real causes, though. Our hair loss myths guide covers hats, dandruff and shampoo. Our guide on creatine and hair loss covers the gym supplement question.
How a dermatologist finds the cause
The AAD says a dermatologist will ask questions, look closely at your scalp and nails, and test your hair. "Gently pulling on your hair tells your dermatologist a lot about how your hair is growing and whether it's prone to breaking" (AAD: diagnosis and treatment). If a disease, low vitamins, hormones or infection are suspected, you may need a blood test or a small scalp sample.
Some men have more than one cause at once. A stressful year can add shedding on top of early pattern loss. That is why a firm answer comes from an exam, not from a photo.
Treatment for pattern hair loss
The drugs our price tables cover treat male pattern hair loss only. A 2024 review says "first-line treatment is minoxidil" and that "Oral finasteride is another treatment available for male patients" (Dakkak et al. 2024, PubMed). First-line means the first choice.
- Finasteride is an FDA-approved pill that lowers DHT. It needs a prescription.
- Minoxidil foam or liquid is approved over the counter for the crown.
The cheapest hair loss plan we track is Keeps at $14 a month, checked November 14, 2026. Our male pattern baldness treatment guide covers every option. Every program, scored on price and care, is on the best online hair loss programs.
Questions
FAQ
What causes hair loss in men?
Inherited male pattern hair loss is the most common cause. It is driven by genes and the hormone DHT, and starts at the temples or crown. Other causes include shedding after stress, illness or weight loss, thyroid disease, low iron or protein, some medicines, immune problems, scalp infections and tight hairstyles.
Why is my hair falling out?
Sudden, heavy shedding all over the scalp is often telogen effluvium. It follows a shock such as illness, surgery, stress or losing 20 pounds or more, usually by a few months. Slow thinning at the temples or crown over years points to pattern hair loss. A dermatologist can tell which you have.
What causes balding?
Balding in men is usually male pattern hair loss. Genes make some hair roots sensitive to DHT, a hormone made from testosterone. Those roots shrink over years and stop growing hair. The hairline moves back into an M shape and the crown thins. Without treatment, the loss continues.
What causes thinning hair?
Thinning can come from pattern hair loss, age, shedding after a stressful event, thyroid problems, or too little iron, protein, zinc or biotin. Too much vitamin A or selenium can also thin hair. Many of these improve once the cause is treated. Pattern thinning needs treatment to slow it.
Can hair loss in men be reversed?
It depends on the cause. Shedding after stress or illness usually stops and regrows within months. Thyroid and nutrient problems improve once treated. Pattern hair loss can be slowed and partly reversed with finasteride or minoxidil, but the gain fades if you stop. Scarring hair loss does not regrow.
When should I see a doctor about hair loss?
See a doctor if hair falls out in patches, comes out suddenly in large amounts, or comes with a sore or scaly scalp. Also go if you feel unwell, have lost weight without trying, or started a new medicine. For slow pattern thinning, earlier treatment works better. Every hair loss price, with its source and read date, is on our hair loss price page.
Check this page with an AI assistant:ChatGPTPerplexityClaude
Not affiliated with OpenAI, Perplexity or Anthropic.