Causes of Hair Loss and Current Treatments

A science-informed overview of common triggers, hair-loss patterns and established treatment approaches.

Dr Hamid HosseiniMD, MBioMed & PhD · Melbourne, AustraliaAbout the author

Hair loss can affect both men and women. Its causes include inherited susceptibility, hormonal changes, some medical conditions, nutritional deficiencies, medications, chemotherapy, radiation treatment and physical or emotional stress. Different forms of hair loss have different underlying mechanisms and may require different approaches 1, 2, 3.

Scientists and clinicians have studied ways to support hair growth and manage hair shedding for many years. Some treatments have strong evidence for specific diagnoses, but results vary, treatment may need to continue and no single approach works for every cause of hair loss 3, 4, 5.

Changes in hormones, age, genetics, nutritional status, health conditions and other factors can alter the normal hair-growth cycle. Understanding the type of hair loss is the first step towards choosing an appropriate treatment 6, 7, 8.

Illustration of hair loss and scalp health — Hair-loss illustration from the original article. View image file (Hamita Shopify Media Library).

What Causes Hair Loss?

Hair loss can be influenced by both factors within the body and external exposures or practices. The distinction is useful for understanding potential triggers, but it does not represent two separate medical diagnoses.

Internal factors

Genetics, androgen sensitivity, hormonal changes, autoimmune conditions, illness and nutritional deficiencies can affect hair growth. In androgenetic alopecia, DHT and inherited follicle sensitivity contribute to progressive miniaturisation of susceptible hair follicles.

External factors

Some medications, medical treatments, repeated traction from tight hairstyles, harsh hair practices and environmental exposures can contribute to shedding or hair-shaft damage. Stress may also trigger telogen effluvium.

Patterns of hair thinning and loss — Illustration of hair-loss patterns from the original article. View image file (Hamita Shopify Media Library).

Recognising Different Hair-Loss Patterns

In male-pattern hair loss, thinning commonly begins at the temples or crown, although patterns vary between individuals. Female-pattern hair loss often presents as gradual thinning across the central scalp, with the frontal hairline relatively preserved. Patchy, sudden or diffuse shedding can point to other causes 3, 9, 10, 11.

Clinicians may use the Hamilton–Norwood scale for male-pattern hair loss and the Ludwig scale for female-pattern hair loss. These classifications describe the distribution and extent of hair loss; they do not replace a clinical diagnosis 10, 11, 12, 13.

Hair-loss treatment options illustration — Overview image of hair-loss treatment options from the original article. View image file (Hamita Shopify Media Library).

Current Hair-Loss Treatments

The most appropriate treatment depends on the diagnosis, severity, medical history and individual preferences. Options may include addressing a nutrient deficiency or underlying medical condition, topical or prescription treatments, and selected procedures such as hair transplantation 3, 4, 9.

Topical minoxidil is commonly used to support growth and reduce progression in certain forms of pattern hair loss. Possible adverse effects include scalp irritation and unwanted hair growth outside the treatment area. Finasteride, usually prescribed orally for suitable male patients, reduces DHT formation; possible adverse effects include sexual dysfunction. Finasteride is not appropriate during pregnancy, and treatment choices should be discussed with a clinician. Other treatments have different risks and benefits 3, 4, 9.

Hair transplantation can be considered for appropriately selected patients, but it is invasive, involves costs and may not be suitable when donor-hair availability or medical factors limit the procedure 4, 9.

Dr Hamid hair-care products illustration — Dr Hamid hair-care illustration from the original article. View image file (Hamita Shopify Media Library).

Scientific References

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Alessandrini A, Bruni F, Piraccini BM, Starace M. Common causes of hair loss - clinical manifestations, trichoscopy and therapy. J Eur Acad Dermatol Venereol. 2021 Mar;35(3):629–40.
Phillips TG, Slomiany WP, Allison R. Hair Loss: Common Causes and Treatment. Am Fam Physician. 2017 Sep 15;96(6):371–8.
Nestor MS, Ablon G, Gade A, Han H, Fischer DL. Treatment options for androgenetic alopecia: Efficacy, side effects, compliance, financial considerations, and ethics. J Cosmet Dermatol. 2021 Dec;20(12):3759–81.
Hadshiew IM, Foitzik K, Arck PC, Paus R. Burden of hair loss: stress and the underestimated psychosocial impact of telogen effluvium and androgenetic alopecia. J Invest Dermatol. 2004 Sep;123(3):455–7.
Park AM, Khan S, Rawnsley J. Hair Biology: Growth and Pigmentation. Facial Plast Surg Clin North Am. 2018 Nov;26(4):415–24.
Thom E. Stress and the Hair Growth Cycle: Cortisol-Induced Hair Growth Disruption. J Drugs Dermatol. 2016 Aug 1;15(8):1001–4.
Buffoli B, Rinaldi F, Labanca M, Sorbellini E, Trink A, Guanziroli E, et al. The human hair: from anatomy to physiology. Int J Dermatol. 2014 Mar;53(3):331–41.
York K, Meah N, Bhoyrul B, Sinclair R. A review of the treatment of male pattern hair loss. Expert Opin Pharmacother. 2020 Apr;21(5):603–12.
Bertoli MJ, Sadoughifar R, Schwartz RA, Lotti TM, Janniger CK. Female pattern hair loss: A comprehensive review. Dermatol Ther. 2020 Nov;33(6):e14055.
Starace M, Orlando G, Alessandrini A, Piraccini BM. Female Androgenetic Alopecia: An Update on Diagnosis and Management. Am J Clin Dermatol. 2020 Feb;21(1):69–84.
Shrivastava SB. Diffuse hair loss in an adult female: approach to diagnosis and management. Indian J Dermatol Venereol Leprol. 2009;75(1):20–7; quiz 27–8.
Gupta M, Mysore V. Classifications of Patterned Hair Loss: A Review. J Cutan Aesthet Surg. 2016;9(1):3–12.