The Common Causes of Excessive Hair Loss in Men

If you're starting to go bald, it could feel like you're losing a piece of your identity. Understanding the cause of your excessive hair loss can help you decide if treatment options are right for you or if your hair will grow back.

Here are some common causes of hair loss in men.

Man looking at hair loss in mirror
becon / iStockPhoto

Surgery or Illness

If you recently underwent a major surgery or are recovering from a serious illness, hair loss is normal. Many people experience dramatic levels of hair loss some weeks after major surgery or after an illness.

While the level of hair loss may appear excessive, it's really no more than a reaction to a specific event, and hair will return to normal after a period of time.


Some anticoagulants (medications that help stop the blood from thickening, or "clotting") and many chemotherapy drugs used in cancer treatments are well known for causing hair loss. Hair usually returns once the medication stops.

Some antidepressants also may result in hair loss, and too much vitamin A can have the same effect.

Hormonal Imbalances

Testosterone is a hormone that's responsible for deeper voices, muscular growth, and sex drive, among other things.

When your body converts testosterone to the less useful dihydrotestosterone (DHT), you can experience hair loss. DHT attacks and shrinks hair follicles and may result in hair thinning or hair loss.

Thyroid Issues

Patients with hyperthyroidism or hypothyroidism often experience hair loss due to a speeding up of the conversion of testosterone to DHT. Even people who are undergoing thyroid treatment are not immune from the hair loss associated with their condition.


If you've been under a lot of pressure at work or at home, you might be able to blame your hair loss on stress. Excessive physical or emotional stress can cause hair to stop growing normally, falling out two or three months later.

Luckily, hair loss due to stress is usually not permanent.

Alopecia Areata

Alopecia areata is an autoimmune condition that is also exacerbated (made worse) by stress. It causes hair to fall out in round patches on the scalp and elsewhere on the body due to your immune system attacking hair follicles.

About 5% of people with alopecia will lose hair on their entire scalp. Typically, hair grows back, but it's common for hair loss to reoccur.

Other Causes

Certain fungal infections can result in hair loss. Losing your hair may also signal some underlying problem, such as diabetes or lupus.

As it is not always possible to assess the cause of rapid or excessive hair loss, it is always worth seeking medical advice to diagnose the cause of your hair loss.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Watras MM, Patel JP, Arya R. Traditional anticoagulants and hair loss: a role for direct oral anticoagulants? A review of the literature. Drugs Real World Outcomes. 2016;3(1):1-6. doi:10.1007/s40801-015-0056-z

  3. Urysiak-czubatka I, Kmieć ML, Broniarczyk-dyła G. Assessment of the usefulness of dihydrotestosterone in the diagnostics of patients with androgenetic alopecia. Postepy Dermatol Alergol. 2014;31(4):207-15. doi:10.5114/pdia.2014.40925

  4. Vincent M, Yogiraj K. A descriptive study of alopecia patterns and their relation to thyroid dysfunction. Int J Trichology. 2013;5(1):57-60. doi:10.4103/0974-7753.114701

  5. Peters EMJ, Müller Y, Snaga W, et al. Hair and stress: A pilot study of hair and cytokine balance alteration in healthy young women under major exam stress. PLoS ONE. 2017;12(4):e0175904. doi:10.1371/journal.pone.0175904

  6. Pratt CH, King LE, Messenger AG, Christiano AM, Sundberg JP. Alopecia areata. Nat Rev Dis Primers. 2017;3:17011. doi:10.1038/nrdp.2017.11

Additional Reading
  • American Academy of Dermatology. Alopecia Areata: Overview.

By Jerry Kennard
 Jerry Kennard, PhD, is a psychologist and associate fellow of the British Psychological Society.