Hair Loss Classification

Every successful medical treatment begins with an accurate diagnosis. In hair restoration, one of the primary objectives of the initial consultation is to determine both the type and the extent of a patient’s hair loss.

Hair loss can be classified according to its underlying cause, including androgenetic alopecia, alopecia areata, frontal fibrosing alopecia, diffuse alopecia, cicatricial (scarring) alopecia, and alopecia universalis, among others.

Because androgenetic alopecia (male pattern hair loss) is by far the most common form of hair loss in men, physicians commonly use the Hamilton–Norwood Scale to assess its progression.

In 1951, James Hamilton first described a series of progressive stages of male pattern baldness based on long-term clinical observations. In 1975, Dr. O’Tar Norwood refined Hamilton’s work, creating the classification system that remains the international standard for evaluating androgenetic alopecia in men today.

Hamilton–Norwood classification

The Hamilton–Norwood Scale classifies male pattern hair loss into seven principal stages:

• Type I – Minimal or no visible hair loss along the frontal hairline.
• Type II – Mild recession at the temples, creating the appearance of an early mature hairline.
• Type III – More pronounced frontotemporal recession. This is generally considered the first stage of clinically significant hair loss. Early thinning at the crown may also begin.
• Type IV – Noticeable hair loss at both the frontal hairline and crown, although a band of hair still separates these two areas.
• Type V – The bridge of hair between the frontal and crown regions becomes progressively narrower.
• Type VI – The frontal and crown areas merge as the separating band disappears.
• Type VII – The most advanced stage, with hair remaining only around the sides and back of the scalp.

Why is hair loss classified?

Determining the stage of hair loss is an essential part of diagnosis and treatment planning.

The Hamilton–Norwood classification allows the physician to:

• Monitor disease progression over time.
• Evaluate the effectiveness of medical treatments.
• Determine whether the patient is a suitable candidate for hair transplantation.
• Estimate the number of follicular units that may be required to achieve the desired result.
• Develop an individualized treatment strategy based on both current hair loss and the likely future progression of androgenetic alopecia.

This classification therefore serves as an important clinical tool rather than simply a descriptive scale.

Frequently Asked Questions

Is a diagnosis necessary before a hair transplant?

Yes. At Instituto Médico del Prado, a comprehensive diagnosis is considered the foundation of every successful treatment. Identifying both the type and severity of hair loss enables Dr. Espinosa Custodio to recommend the most appropriate medical therapies and determine whether hair transplantation is the best option. Every initial consultation and surgical assessment is performed personally by Dr. Espinosa Custodio.

What is the purpose of the Hamilton–Norwood Scale?

The scale provides a standardized way of documenting the extent of androgenetic alopecia. It helps both the patient and the physician understand the current stage of hair loss, estimate future progression, and calculate approximately how many follicular units may be required if hair transplantation is indicated.

Can I determine my own stage of hair loss?

The Hamilton–Norwood Scale can provide a general indication of the degree of hair loss you may have. However, only a consultation with an experienced hair restoration specialist can accurately diagnose the type of alopecia, determine its stage, assess the donor area, and recommend the most appropriate treatment plan.

Dr. Espinosa Custodio works at Instituto Médico del Prado, his hair clinic in Madrid, and performs hair transplants in Mexico, twice a year. If you would like to make an appointment, you can contact us on +34 912 468 664, on WhatsApp +34 627 396 322 or on the contact page of our website. From Mexico you can contact us at +52 55 4590 9909.