Types of alopecia
Alopecia is broadly classified as either nonscarring (hair can regrow) or scarring (hair loss is permanent). Nonscarring alopecia is the most common type. It doesn’t destroy the follicles, so hair loss may be temporary. Scarring alopecia happens when hair follicle damage is irreversible, so hair can’t grow back.
In alopecia areata, the immune system mistakenly attacks hair follicles, causing hair loss. There are different types, which vary by the amount and location of hair loss.
- Alopecia areata (patchy) causes one or more round or oval bald patches on the scalp or other places on the body that grow hair.
- Alopecia areata totalis causes complete hair loss on the scalp.
- Alopecia areata universalis causes total hair loss on the body, including eyebrows, eyelashes, chest, armpits, and pubic area.
- Diffuse alopecia areata causes widespread hair thinning across the scalp.
- Ophiasis alopecia areata causes hair loss in a snake-like pattern along the back of the head and around the ears.
Also known as male-pattern baldness and female-pattern baldness, androgenetic alopecia causes gradual hair loss on the scalp after puberty. For people assigned male at birth, hair thinning usually appears in a circular pattern on the top and front of the head. For people assigned female at birth, thinning occurs all over the scalp but maintains a normal hairline.
Traction alopecia happens when tight hairstyles pull on the hair too much. This includes tight braids, buns, ponytails, updos, cornrows, hair extensions, weaves, and sleeping in rollers. It can also be caused by constant rubbing from a hat, headscarf, or other head covering, especially if the hair is pulled back tightly underneath.
Telogen effluvium causes excessive hair shedding when many hair follicles enter the resting phase (telogen) at the same time. It’s usually triggered by stressors like surgery, major weight loss, hormonal changes, or severe illness. Hair typically regrows once the underlying cause is resolved.
Anagen effluvium, also called chemotherapy-induced alopecia, is rapid hair loss that happens when hair follicles are damaged during the growth phase. It’s often caused by chemotherapy, radiation, or toxins, but hair usually grows back once the cause is removed.
Also called cicatricial alopecia, some types of scarring alopecia include:
- Lichen planopilaris (LPP) causes inflammation and scarring of the hair follicles. It’s the most common type of scarring alopecia.
- Central centrifugal cicatricial alopecia (CCCA) starts at the crown and spreads outward. It’s the most common hair loss type in Black people assigned female at birth.
- Frontal fibrosing alopecia (FFA) causes hair loss on the front and sides of the scalp and may also affect the eyebrows, eyelashes, and other body parts.