Hair doesn't grow continuously. Each follicle runs through a repeating cycle, and every follicle on your scalp is at its own point in it. Understanding that cycle is the key to understanding both thinning and realistic expectations.
The four phases
- Anagen (growth): the longest phase, typically lasting two to seven years. Most of your hair is in this phase at any given time.
- Catagen (transition): a short phase of up to about two weeks, where the follicle winds down and shrinks.
- Telogen (rest): the follicle rests for up to around three months.
- Exogen (shedding): the old hair is released, and the follicle can start a new growth phase.
Where thinning comes from
Researchers describe the early end of the growth phase as a key driver of gradual thinning. When anagen is cut short, hairs have less time to grow long and thick, and more follicles sit in the resting phase at any one moment. That is why supporting a longer growth phase is seen as a central strategy in preventing hair loss.
The follicle's blood supply plays a part too. Cells at the base of the follicle release a growth factor called VEGF, which helps form the small blood vessels that feed the follicle. Studies have found lower VEGF levels in follicles affected by hair loss. Some plant extracts, rosemary included, have raised VEGF in animal studies, but rosemary's effect on scalp blood flow has not been directly measured in people.
Not all thinning is the same
Hair loss has many possible causes: genetics and hormones, stress, iron or other nutritional deficiencies, thyroid problems, certain medications, and autoimmune conditions. A topical serum can only address part of that picture. If your hair loss is sudden, patchy, or comes with other symptoms, a doctor or dermatologist should be your first stop.
The honest takeaway
Because hair moves through this cycle slowly, visible change is measured in months. In the main rosemary trial, nothing measurable had changed at three months; the results appeared at six. That is the window we ask you to judge us on.
Read the originals
- Park S, Lee J. Modulation of hair growth promoting effect by natural products. Pharmaceutics. 2021;13(12):2163. Read the full paper
- Gokce N, et al. An overview of the genetic aspects of hair loss and its connection with nutrition. Journal of Preventive Medicine and Hygiene. 2022;63(2 Suppl 3):E228–E238. Read the full paper
This article is general cosmetic information only, not medical advice. STRND is a cosmetic product and is not intended to diagnose or treat any medical condition.