Learn about the science-backed ingredients, lifestyle solutions and more that may affect the growth phases of your hair.

Approximately half of all women will experience hair loss or thinning by the age of 50 [1]. While genetics play a large role, other factors can affect how hair appears and feels.

By understanding how your hair works optimally, you can develop a routine that addresses the root of the problem, instead of just masking the symptoms. Using her proactive approach to achieving stellar strands, Dr Mamina Turegano, a board-certified dermatologist in Louisiana, explains each phase of the hair-growth cycle. 

With that, here are the four phases of hair growth:

The antigen/growing phase

Turegano explains that the antigen phase is the stage in which most of your hair is currently being produced by the follicle. Currently, 90 percent of the population is in this growth phase. 

The length of time your hair stays in this initial phase determines how long it can grow. She points out that people with very long hair (to the base of the back and beyond) have a genetically long antigen phase. “For most, it lasts about three to five years, but for those with hair that can grow long, this phase can go on for up to seven years.”

The catagen/regression phase

As soon as a new strand is sprouted and fully formed, the follicle proceeds to the catagen phase, which typically lasts a week or two. The follicle starts to separate from the bottom during this stage. Despite not being ready to shed yet, it is getting ready for the next phase.

The telogen/resting phase

The hair stops growing during this inactive stage, which lasts for about three to five months per strand. Consequently, Turegano says that the strands are nearly completely detached and ready to fall out. At any given time, you’ll have some strands in this phase that are preparing to depart and others newly emerging in the antigen phase.

The exogen/shedding phase

At this stage, strands start to clog your hairbrush or fall onto your favorite sweater. It’s typical to lose between 50 and 100 a day. 

Factors that affect hair growth

The hair thinning and loss issues Turegano sees are common. The most common culprit of hair loss is telogen effluvium, which occurs when your body undergoes a shock from illness, surgery or the loss of a loved one. 

In response to the body’s signal, a lot of hairs are converted from the antigen growing phase to the telogen resting phase. This results in a prematurely shortening of the growth phase.

Due to the length of the telogen phase, you may not notice significant shedding or thinning until three to five months after entering telogen. Turegano initially asks patients what happened three to five months ago.

This disruption of the delicate balance can usually be traced to a specific event. It can take several months to recalibrate and return to your normal growth phase-and that will also rely on whether or not you’re still being exposed to that stressor.

Taking care of your hair is like running a marathon

The two most common nutritional deficiencies that can cause thinning hair are iron deficiency and vitamin D deficiency, according to Turegano. A supplement can make a huge difference in the health of your hair, but you should consult your doctor first for a personalized strategy. In addition, underlying conditions can aggravate hair shedding, she says, so she does a full blood panel to rule out any low-hanging fruit.

Thyroid disease and hormonal disorders can be among them, since estrogen can also stimulate hair follicles, whether you are going through menopause or being postpartum. In other words, your hair can also be affected when the hormone disappears so acutely.

Scalp health is also important. Seborrheic dermatitis, the most frequent cause of dandruff, also causes inflammation on the scalp, she says. “People get itchy, flaky scalps that can aggravate hair loss.”

Creating a hair-care routine that optimizes growth

Your stress levels and hormone levels are under control, you’re eating a balanced diet while supplementing with a multivitamin, and a sunny, vitamin-d-rich vacation is just around the corner. There’s still a chance you’re harming your hair. Using harsh chemical treatments like highlights and coloring, heat styling and more on a consistent basis can damage and dull your hair before its time.

Hair health depends on scalp health

In order to strengthen strands and support the scalp, Turegano carefully curates her clients’ hair-care routine. In addition to treating your hair gently as you do your skin, she recommends minimizing chemical treatments and frequency, removing tangles carefully, avoiding super-tight topknots and ponytails and wrapping delicate damp strands in soft microfiber towels in place of regular ones, as well as picking the right shampoos, conditioners and other products. 

Keep in mind that each strand of hair in your mirror is at a different stage in the growth cycle, so you won’t see results immediately. It takes commitment to have healthy hair,” says Turegano. You can transform both the health of your scalp and your hair for the long run by committing to a scientifically proven routine [2]

[1] https://my.clevelandclinic.org/health/diseases/16921-hair-loss-in-women
[2] https://www.elle.com/beauty/a42939203/what-to-know-about-the-4-phases-of-hair-growth/