Does hair grow back thicker after shaving?
This is may seem a purely female concern, but who knows how many spotty teenage boys have assiduously plied the razor in the hope of transforming downy fluff into a manly beard? As it happens the definitive study on this point was conducted on men’s leg hair but the results are assumed to apply to both sexes and all parts of the body. In short, shaving has no effect on hair growth.
Shaving does change the appearance of the hair as it begins to grow back in. Since shaving only lops off the hair at the skin, instead of removing it completely, the hairs just keep coming. The stubble that grows back lacks the tapered ends of longer hairs and, because it hasn’t been exposed to the bleaching effects of light or chemicals, will also appear darker than before. Together these give the impression of thicker hair, but that impression won’t last.
That hair could grow back thicker is not an outrageous idea. Trimming the fur of mice and guinea pigs can stimulate hair growth. Other more drastic hair removal techniques like plucking and waxing can damage hair follicles and affect regrowth.
Changes in hair growth are actually routine. It happens most dramatically at puberty when some hair follicles expand and previously light, downy vellus hairs become thicker, darker terminal hairs. In baldness the follicles shrink, and the hairs along with them. Bald men (and women) typically still have hair, it’s just very light. In addition the rate of growth and colour of hairs vary over time.
In all these cases the number of hairs stays the same, while the hairs themselves change size. But the number of hairs can also change. Hair follicles go through cycles of growth and rest. If the proportion in each phase changes for any reason then the affected region will become more or less hairy.
Fascinating though all these change may be, not one of them is brought about by shaving. Genetics, hormones, nutrition, disease and injury can all affect the growth of hair, but shaving just doesn’t cut it.