How Hair Grows: Understanding The Three Stages Of Hair Growth

By Lisa Rhodes, MD April 19, 2016 3 Comments

hair growth stages

Each year millions of Americans deal with some form of hair loss or hair thinning. In order to determine which type of hair loss treatment is best suited for an individual’s situation, it is important to understand how hair grows.

Hair grows from a hair follicle (sometimes called the root) located under the skin. Blood vessels situated at the bottom of each follicle provide a nourishing blood flow that enables the hair to grow. From the time your hair begins to grow until the time it falls out, each individual hair passes through a growth cycle of three distinct stages: Anagen, Catagen, and Telogen.

Anagen Phase

The anagen phase is commonly referred to as the growing phase as the hair grows about half an inch in length every 28 days during this period. While the amount of time the follicle remains in the anagen phase differs from person to person (it is determined genetically), this phase typically lasts from two to six years. The length of time the hair is in the anagen stage also determines how long an individual’s uncut hair can grow, with most falling within a range of 18 to 30 inches.

Catagen Phase

The catagen phase is a short transitional phase that lasts about two weeks. During this phase the follicle begins to shrink and the individual hair becomes restricted from nourishment (blood supply) provided by the underlying vessel.

Telogen Phase

The telogen phase is a resting phase which lasts around 3 months. During this phase the hair is released from the follicle and falls out and a new hair begins to grow in its place. Most healthy scalps will shed 50 to 150 individual stands of hair daily.

How the hair regrowth cycle affects hair thinning and hair loss

Each hair follicle is independent and goes through this growth cycle at different times. Hair loss or balding occurs when the natural growth cycle becomes disrupted; particularly when either the anagen phase shortens or the telogen phase increases (or a combination of both).

Disruption of the growth cycle can stem from many different factors including metabolic imbalances, illness, improper nutrition, stress, and genetics. Fortunately there are many effective hair restoration treatments and medications that can counteract disruptions to the hair growth cycle.

Please contact us today to learn more.


Lisa Rhodes, MD

Lisa Zanetti Rhodes, MD received her Dermatology specialty training at the McGaw Medical Center of Northwestern University in Chicago, where she served as Dermatology Chief Resident in her last year. Dr. Rhodes is Board Certified by the American Board of Dermatology, and is a member of the Texas Medical Association, the Travis County Medical Society, and the Alpha Omega Alpha Medical Honor Society. Dr. Rhodes serves as a community preceptor at The University of Texas Medical Branch School of Medicine.

3 Responses to “How Hair Grows: Understanding The Three Stages Of Hair Growth”

  1. Jordan says:

    Very interesting! It’s cool to see the science behind hair growth and how it works. Whether you’re trying to get hair to grow better or faster, or make sure hair stays gone longer, it’s good to know this process.

  2. Helen says:

    I am a lupus and rheumatoid arthritis patient and went from having a head full of thick long hair to being just about bald! Once I began to lose my hair it started coming out at a very fast rate, this was before my diagnosis. Now that I have a diagnosis and am on medicine the back of my hair is beginning to come in and fill out, but certain medicines will cause it to fall again. Still, I am glad to see that my hair follicles are still there and that my hair is able to regrow. However, I am a woman who enjoy having my own hair I abhor wigs to be honest. They are hot, expensive to keep buying and feel funny.

    • WD Staff WD Staff says:

      Hello Helen,

      Thank you for reading our blog and submitting your comment. We are very sorry to hear about your hair loss issue. Since this is definitely a medical situation we would first encourage you to visit your current physician treating your conditions to ask if either PRP or hair transplant surgery is a viable option. Especially since you indicate that some hair regrowth is occurring. There is a good chance the recommendation will be to allow natural regrowth to continue prior to intervention.

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