“Shaving makes hair grow back thicker”

The persistent belief that shaving causes hair to grow back thicker, darker, or faster is a common misconception that has circulated for generations. This enduring myth likely stems from the immediate visual and tactile changes people experience shortly after shaving. As early as the 1920s, scientific studies began to debunk this idea, with research by Dr. Mildred Trotter in particular gaining attention for showing no hair growth stimulation by shaving in humans. Despite this early evidence, the myth has continued to be passed down, influencing grooming habits and perceptions of hair growth.

Scientifically, shaving only affects the dead part of the hair shaft above the skin's surface and has no impact on the hair follicle beneath, which is responsible for hair growth, thickness, and color. Hair thickness and growth rate are determined by genetics and hormones, not by external actions like cutting. When a razor cuts hair, it creates a blunt tip, unlike the naturally tapered end of unshaven hair. This blunt end can make the regrowing hair feel coarser or stubbier to the touch, and it may appear more noticeable or darker simply because the fresh hair has not yet been exposed to elements like sun, soaps, or other chemicals that can lighten hair over time.

People commonly believe this myth due to several perceptual illusions. The blunt, freshly cut hairs emerging from the skin can feel stiff and create an impression of increased density and coarseness. Furthermore, many individuals begin shaving during adolescence, a period when hair naturally darkens and thickens due to hormonal changes, leading to an incorrect association between shaving and these natural developments. The simultaneous regrowth of many hairs that were cut at the same length can also contribute to the perception of increased thickness. Ultimately, what is perceived as thicker or darker hair is merely a visual and tactile trick, not a change in the hair's fundamental properties or growth cycle.