Do Hair and Nails Keep Growing After Being Cut? The Science Behind the Process

By Dr. Bryan Rithesh Miranda

Have you ever wondered why you need to cut your hair or nails regularly, and what happens after you trim them? Hair and nails are fascinating parts of our body that constantly grow, even after being cut.

How Hair Grows?

Hair is made up of a protein called keratin. This protein is produced by cells in the hair follicle, which is located under your skin. The part of the hair you can see is called the "shaft," and the base of the hair, called the "root," is located in the follicle.

Diagram illustrating the anatomy of hair.

When you cut your hair, you’re only trimming the shaft, which is made up of dead cells. The living cells in the follicle keep producing keratin, allowing the hair to continue growing. That’s why your hair doesn’t stop growing after a haircut!

The Hair Growth Cycle:

Hair growth follows three stages:

Illustration of the hair growth cycle, detailing the Anagen (growth phase lasting 2–6 years), Catagen (transitional phase lasting 1-2 weeks), and Telogen (resting phase lasting 5–6 weeks) stages, showing the changes in the hair follicle and papilla.

1. Anagen (growth phase)

2. Catagen (transition phase)

3. Telogen (resting phase)

Hair typically grows for 2 to 6 years before it falls out, and the cycle begins again.

How Nails Grow?

Just like hair, nails are also made of keratin. Nails grow from a part of your finger or toe called the "nail matrix," which is located under the skin at the base of your nail (the cuticle area).

Detailed illustration of nail anatomy, showcasing the front and side views.

When you trim your nails, you’re cutting off the free edge, which is the part that has grown out beyond your fingertip. The cells in the nail matrix continue to push new keratin cells forward, and as a result, your nails grow longer.

Nail Growth Cycle:

Chart illustrating the average yearly growth rates of fingernails.

Fingernails grow about 3.5 millimetres per month, while toenails grow slower, around 1.6 millimetres per month.

Why Do Hair and Nails Keep Growing?

Hair and nails grow because of the continuous activity in the hair follicles and nail matrix. These areas are where living cells divide, grow, and eventually die, leaving behind the keratin that forms your hair and nails. Once they emerge, they no longer have living cells, which is why cutting them doesn’t cause pain.

Uses of Hair and Nails

1. Protection: Hair helps regulate body temperature and protects sensitive areas like your scalp from sun damage. Eyelashes and eyebrows prevent dirt and sweat from entering your eyes.

2. Touch Sensation: Fingernails protect the sensitive tips of your fingers, and they help us pick up small objects by providing extra support and precision.

3. Health Indicators: The condition of your hair and nails can also be an indicator of your overall health. Dry or brittle nails and hair may be signs of nutritional deficiencies or other health concerns.

Hair and nails are constantly growing because of the living cells in your hair follicles and nail matrix. Though you cut them, the growth continues beneath the surface. Regular maintenance is needed to keep them healthy, and their growth patterns can even give you clues about your health. Understanding this process helps us appreciate how our bodies work in fascinating ways!