Can hair grow back? It depends on the cause

"Will my hair grow back?" is probably the most common question people ask when they notice hair loss. The answer is not the same for everyone. It depends on why the hair is falling out, and in particular on whether the hair follicle, the tiny structure in the skin that makes each hair, is still alive and working.

The key idea: is the follicle still there?

A normal scalp has follicles that cycle between growing and resting. At any time, most hairs are growing and a smaller share are resting, before they shed and are replaced ¹. Losing about 50 to 100 hairs a day is normal ².

Broadly, hair loss falls into three groups:

• The follicle is healthy but disturbed, for example by illness, stress or a medicine. Hair usually comes back once the trigger is gone.
• The follicle is gradually shrinking, as in pattern hair loss. Treatment can slow this, but the tendency remains.
• The follicle is destroyed and replaced by scar tissue. Hair in those areas does not come back.

Causes where hair usually grows back

Shedding after a trigger (telogen effluvium). Fever, surgery, childbirth, a crash diet, low iron, thyroid problems and some medicines can push many hairs into the resting phase at once, leading to heavy shedding a few months later ¹. Once the cause is found and dealt with, hair usually grows back ¹. The NHS notes that hair loss from a medical condition usually stops or grows back once you have recovered ². See chronic telogen effluvium if shedding goes on for many months.

Shedding after pregnancy. Many women shed more hair a few months after giving birth. This is temporary, and most regain their usual fullness by the child's first birthday ³. See hair changes in pregnancy.

Hair loss from cancer treatment (anagen effluvium). Chemotherapy can cause sudden loss of growing hairs. Hair usually starts to come back a few months after treatment ends, sometimes with a different texture or colour ⁴. Radiotherapy to the scalp may leave incomplete new growth in some people ⁴. See anagen effluvium.

Alopecia areata. Here the immune system attacks follicles but does not destroy them. In most cases hair grows back, though new episodes can occur, and recovery is less likely when hair loss is extensive ⁵. See whether alopecia areata goes away on its own.

Causes that tend to progress

Pattern hair loss (androgenetic alopecia) in men and women runs in families and tends to be lasting ². Hairs become finer and shorter over years. Treatments such as minoxidil, and finasteride for men, can slow loss and in some people improve density, but they work only as long as they are used ². Starting earlier, while follicles are still producing hair, generally gives treatment more to work with. See an evidence-based overview of treatments.

Traction alopecia from tight hairstyles often improves if the pulling stops early. Long-standing traction can lead to lasting loss ⁶.

Causes where hair does not grow back

Scarring alopecias, such as frontal fibrosing alopecia and lichen planopilaris, destroy follicles ⁷. Treatment aims to stop the condition spreading, protecting the hair that remains. Early diagnosis matters because hair already lost to scarring cannot return ⁷. See scarring alopecia.

How a doctor works out the cause

A doctor will usually:

• ask when the hair loss started, what happened in the months before, and about medicines, diet and family history
• look at the pattern: patches, diffuse thinning, or a receding hairline
• examine the scalp, sometimes with a magnifier (trichoscopy)
• order blood tests if needed, for example for iron or thyroid function (see blood tests)
• occasionally take a small scalp biopsy

What you can do now

• Do not panic about daily shedding if it is within the normal range ².
• See a doctor if hair loss is sudden, patchy, comes with itching, pain or redness, or is affecting your wellbeing. See what to do first.
• Take photos to track changes objectively.
• Be wary of promises. No treatment works for everyone ², and products claiming to bring back hair regardless of the cause are not being honest.

The bottom line

Hair often grows back after temporary triggers, can be helped to a degree in pattern hair loss, and does not return where follicles are scarred. Getting the right diagnosis is the first and most important step.

Frequently asked questions

Will hair grow back after stress or illness?

Usually, yes. Shedding after a trigger normally settles once the cause is dealt with, and hair grows back over the following months ^{1 2}.

Can a bald patch from pattern hair loss grow back?

Pattern hair loss tends to progress. Treatment can slow it and may improve density in some people, but works only while used ².

Does hair grow back after chemotherapy?

It usually starts to come back a few months after treatment ends, sometimes with a different texture or colour ⁴.

Why does hair not grow back in scarring alopecia?

Because the follicles are destroyed and replaced by scar tissue ⁷.

Educational content. Not medical advice.