4 Stages of Hair Growth (2024)

Your hair grows in a cycle of four stages or phases. The stages are anagen (growth stage), catagen (regression stage), telogen (resting stage), and exogen (shedding stage). Learn more about these stages, how long each one lasts, and what can affect the hair growth cycle, including chemotherapy.

How Does the Hair Follicle Work?

Hair follicles are pores, or small tubes, that contain a root from which hair grows. Follicles develop primarily in the two top layers of skin. They connect to blood vessels at a rounded base that contains a root called the dermal papilla. The papilla sends signals about growth as well as the color and size of the hair strands.

When your hair is in the growing phase, a strand emerges from the root and grows through the hole at the top of the follicle.

The 4 Stages of Hair Growth

The four stages of the hair growth cycle are:

1. Anagen
2. Catagen
3. Telogen
4. Exogen

Each follicle goes through an estimated 10 to 30 cycles during your life.

Anagen Stage

The anagen stage is when your hair is growing. During this phase, the bottom of the follicle expands and produces the fibers, which will become strands of hair. In the "proanagen phase," the follicle makes cells that will form the hair. When the hair reaches the skin's surface, that is the "metanagen" phase.

The anagen phase typically lasts for two to eight years for each follicle. About 90% of the follicles on the scalp are in the anagen stage at any one time. Hair grows at a rate of about a third of a millimeter a day, or about 15 centimeters a year, which is nearly 6 inches.

Catagen Stage

The catagen phase is a transition from the active phase to the third phase, lasting about two weeks. During this stage, the hair follicles become slightly smaller and detach from the papilla.

Telogen Stage

The telogen stage of the hair cycle is a resting phase, during which the hair doesn't grow, and the follicle is dormant. About 10% to 15% of the hairs on your body are in this resting phase at any one time, which typically lasts for a few months.

Exogen Stage

Not all descriptions of the hair cycle include the exogen stage, but it refers to the phase when hairs are shed from the body, pushed out as new strands emerge from the follicle, and when the anagen phase begins again. About 100 to 150 follicles shed hair each day, though the number varies from person to person.

What Can Disrupt the Hair Growth Cycle?

If the hair cycle is disrupted, hair may begin to fall out more quickly than it can grow back, resulting in thinning hair, a receding hairline, or losing hair in patches. Many factors can disrupt the hair cycle, including:

• Thyroid or other hormone imbalances
• Inflammation
• Stress
• Genetics
• Rapid weight loss
• Giving birth
• Surgery
• Autoimmune conditions such as psoriasis, lupus, or autoimmune thyroid disease
• Nutritional deficiencies, including vitamin D, iron, and protein
• Medications, including blood thinners, oral acne medication, and birth control pills.
• Medical treatments like chemotherapy

Healthy Hair Growth Tips

To encourage hair growth, make sure you get an adequate supply of vitamins and nutrients, including vitamin D, vitamin C, and iron. Some hair care supplements contain these nutrients, but you can also get them from your diet.

Many claims about other nutrients, ingredients, or techniques, likescalp massage,promoting hair growth exist, but the evidence is limited, though research continues.

You can keep your hair healthy and reduce loss by:

• Choosing a shampoo designed for your hair type
• Washing oily hair more frequently, up to once a day
• Concentrating your shampoo on the scalp, where the oil and dirt build up
• Using conditioner on the tips of your hair to build strength and help protect it from harmful ultraviolet (UV) rays
• Protecting your hair when swimming to avoid exposure to harsh chemicals

Research into the gene FGF5, which regulates hair length and plays a role in the transition from the anagen to the telogen phase, has shown that inhibiting the gene may extend the anagen phase of hair growth, but there are no Food and Drug Administration (FDA)-approved treatments using this approach at this time.

Summary

Your hair cycles repeatedly through four different stages during your lifetime. They are the active or anagen phase when your hair is growing, the catagen phase when it is transitioning to the telogen or resting phase, and the exogen phase when the hair follicle that produces hair is dormant.

Many factors can disrupt the hair cycle, including nutritional deficiencies, disease, stress, and genetics. To keep your hair healthy, eat a balanced diet, use shampoo and conditioner for your hair type, and protect it from too much sun or too many chemicals.