Encyclopedia
Hair loss conditions, A to Z
Not all hair loss is the same. Find your situation below to learn the signs, causes and what can help — in plain English.
Condition and treatment details have not been independently medically reviewed.
Visual guide
Norwood & Ludwig hair loss stages →
See what each stage looks like and which options fit it.
Non-scarring
Androgenetic alopecia
Male or female pattern hair loss
The most common cause of hair loss worldwide. Genetics and sensitivity to hormones called androgens (mainly DHT) make follicles gradually shrink, so hairs grow finer and shorter over years.
Alopecia areata
Patchy autoimmune hair loss
An autoimmune condition where the immune system attacks hair follicles, causing smooth round patches of hair loss. It can also affect beards, eyebrows and nails.
Traction alopecia
Hair loss from tension
Hair loss caused by repeated pulling from tight hairstyles such as braids, weaves, extensions, tight ponytails or buns.
Trichotillomania
Hair-pulling disorder
A body-focused repetitive behavior where a person feels urges to pull out their hair, leading to irregular patches.
Shedding
Telogen effluvium
Stress shedding
A sudden increase in shedding that happens when a stressor pushes many hairs into the resting (telogen) phase at once. Shedding typically starts 2–3 months after the trigger.
Thyroid-related hair loss
Hypo- and hyperthyroid shedding
Both underactive and overactive thyroid can cause diffuse thinning. Hair typically improves once thyroid levels are treated.
Iron deficiency hair loss
Low ferritin shedding
Low iron stores (ferritin) are linked with increased shedding, especially in women with heavy periods or plant-based diets.
Anagen effluvium
Chemotherapy hair loss
Rapid hair loss during the growing phase, most commonly from chemotherapy or radiation, starting within days to weeks.
Scarring
Scarring alopecia
Cicatricial alopecia
A group of conditions where inflammation destroys follicles and replaces them with scar tissue, making hair loss permanent in affected areas.
Frontal fibrosing alopecia
FFA
A scarring alopecia causing a slowly receding frontal hairline and eyebrow loss, most often in postmenopausal women.
Life stage
Postpartum hair loss
Shedding after pregnancy
A common, temporary telogen effluvium that begins 2–4 months after giving birth as hormone levels fall back to normal.
Menopause hair thinning
Perimenopausal hair loss
Falling estrogen can unmask female pattern hair loss and make hair drier and finer during perimenopause and after.
Hair shaft & scalp
Seborrheic dermatitis
Dandruff's stronger cousin
A common inflammatory scalp condition causing greasy yellow flakes and redness, linked to Malassezia yeast. It rarely causes lasting hair loss but can worsen shedding.
Scalp psoriasis
Plaque psoriasis of the scalp
An immune skin condition that forms thick silvery plaques on the scalp. Scratching and heavy scale can cause temporary shedding.
Tinea capitis
Scalp ringworm
A contagious fungal infection of the scalp causing scaly patches and broken hairs, most common in children.
Hair breakage
Trichorrhexis / hair shaft damage
Hair that snaps along the shaft rather than falling from the root. It looks like thinning but the follicle is fine.
This content is for educational purposes only and is not medical advice. It is not intended to diagnose, treat, cure or prevent any disease. Speak with a qualified healthcare professional about your individual situation.