---
title: "Hair Loss Science – Sons IE"
description: "The science behind male hair loss. Learn how DHT, genetics, and lifestyle drive hair loss, and how Sons Ireland treatments target the root causes."
url: "https://sons.ie/pages/hair-loss-science"
language: "en"
retrieved: "2026-11-02T00:55:49Z"
---

# How It Works

What’s hair loss all about then? We know it can be hard to get a full picture of what’s going on, so we’ll tell it to you straight. Here’s the science behind why guys lose their hair, how our products work, and what you can expect from treatment.

### The normal hair growth cycle

Hair normally grows, falls out, and regrows in a cycle, which can be broken down into four main phases.

### 1. Anagen (growing phase)

The strand of hair grows upwards from the root, with a nourishing blood supply to the follicle. This phase lasts 2–7 years and determines the length of our hair.

### 2. Catagen (regression phase)

The follicle shrinks as it moves away from the blood supply. This phase lasts about 10 days.

### 3. Telogen (resting phase)

The old shrunken follicle rests while a new hair begins to grow behind it. 10–15% of hairs are in this phase at any one time, which lasts around 3 months.

### 4. Exogen (shedding phase)

The hair is gradually loosened and the root detaches from the follicle. The strand falls out, and the cycle starts again.

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### Male pattern hair loss

Male pattern hair loss is a hereditary condition that affects two thirds of guys by age 35. Men who inherit this trait have a genetic sensitivity to a byproduct of testosterone called dihydrotestosterone (DHT) which slows and halts the normal hair growth cycle. DHT builds up around follicles, shrinking them over time and causing hair strands to thin, shorten, then eventually fall out – and not grow back,as they normally would.

### The Norwood Scale

The degree and progression of male pattern hair loss is assessed using the Norwood classification system, which has seven stages. Identifying where you are at on this scale helps determine the correct treatment.

No hair loss

1

An adult hairline

2

A mature hairline

Mild hair loss

3

Light recession around the temples

4

Deeper recession around the temples and crown

Moderate hair loss

5

6

Significant recession around the temples and crown

Advanced hair loss

7

Advanced recession and bridging hair begins to thin

8

Full recession and loss of hair from the top of the head

## What our products do

Oral Tablet blocks DHT, protecting follicles from shrinking and hair strands from thinning. Minoxidil increases blood flow, revitalising shrunken follicles. Our DHT blocking Shampoo enhances the effects of Finasteride, and our Biotin vitamin promotes hair health.

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Source: https://sons.ie/pages/hair-loss-science