What factors contribute to new hair growth?

Reviewed by Yoshinori Abe, MD

Internal Medicine

New hair growth depends on three key factors: hormonal signals, the number of stem cells in hair follicles, and the biological processes that regulate the hair growth cycle. Hormones such as androgens and estrogens directly affect follicle activity, while follicular stem cells determine how well hair can regenerate. Together, these elements control whether hair grows, rests, or sheds.

If you're noticing changes in your hair growth, it could point to an underlying issue worth exploring—ranging from hormonal imbalances to nutritional deficiencies or scalp conditions. Since hair changes often signal something deeper, the smartest next step is to get clarity fast. Take a free, instant, online symptom check to better understand what may be causing your symptoms and confidently navigate your next steps.

Reviewed for medical accuracy: 07/15/2026

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Explanation

Hair growth is a complex process influenced by multiple factors, including stress level.

Hormonal Effects: Hormones play a crucial role in hair growth. They can affect how hair follicles, which are tiny sacs in the skin where hair grows, behave and develop.

Dermal Papilla Cells: These are special cells found at the base of hair follicles. The number of these cells can determine the size, shape, and growth of the hair. More cells can lead to bigger and longer hair.

Regulation Mechanisms: The body has various processes that regulate hair growth. These processes ensure that hair grows, rests, and sheds in a cycle. Proper regulation is essential for healthy hair growth.

Overall, a combination of hormones, special cells in the hair roots, and the body's regulation processes all contribute to how hair grows. If you're experiencing unexpected hair changes or other concerning symptoms, take a free symptom checker test to better understand what might be affecting your hair health.

(References)

Ogawa H, & Hattori M. (1983). Regulation mechanisms of hair growth. Current problems in dermatology, 6140129.
Chi W, Wu E, & Morgan BA. (2013). Dermal papilla cell number specifies hair size, shape and .... Development (Cambridge, England), 23487317.
Grymowicz M, Rudnicka E, Podfigurna A, Napierala P, Smolarczyk R, Smolarczyk K, & Meczekalski B. (2020). Hormonal Effects on Hair Follicles. International journal of molecular sciences, 32731328.

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