Does hair grow back thicker after shaving?

It has been a long standing idea that if you shave some hair, then it will grow back in thicker. This appears to be mainly regarding facial hair, however it certainly isn't true for all types of hair. Women especially can tend to be very paranoid about shaving any facial hair that they might have, from fear that shaving it somehow encourages more of it to grow and that they will end up with a full beard.

Certainly as young men grow up and begin to shave the hair seems to get thicker as they shave it and it grows back. But then again this could well be just as natural process as they grow. Similarly much older men past retirement age sometimes need to shave twice per day, where in their youth it was only once every couple of days. And at advanced ages men are certainly more capable of growing full beards that they might not have been able to in their youth or even middle age as well as they can in old age. Some of this might just be caused by the skin becoming looser, but that doesn't account for it in every case.

Certainly hair growth is an individual thing, but it does seem that either as you get older or as you shave more hair gets thicker in some places. This urban legend certainly doesn't always ring true however, for example balding men who shave their head of its remaining hair don't then eventually have a full head of hair back after sufficient shaving time. More often they eventually go bold completely, and their hair thins out just the same as it always did.

The origin of this myth probably arose because when hair grows out it becomes thinner at the tip, thus giving it the appearance of being thinner than it really is. Then when it is shaved the hair that grows back is slightly thicker than the end of the hair was previously, giving the appearance of it being thicker.

Keeping a particular area of hair constantly shaved can cause it to become more course and stubbly over time. This is because the nutrients and chemicals that cause the hair to grow become concentrated in the base of the hair, rather then being able to grow out and expand. This then makes the hair that is being shaved stronger and thicker at its base. However this has little effect on the thickness of the hair when it grows out, at which time it returns to its natural state.

In terms of hair growth it is a well-known fact that trimming the tip of the hair from time to time encourages it to grow faster and a little longer then it would have. Whether this can be applied to all hair is another matter. It is known that there is variation between hair growths even in the same place. So some hairs are growing faster then others. When they are then all shaved and are starting from the same point, they might look slightly thicker for the first few days.

So shaving a patch of hair that is fine and soft can cause it to become more stubbly and course. This does not however mean that there will be any more of it, or that it will grow any faster than it had been. The only increased growth in hair that's been cut is for the first day or two only, at which point it grows slowly again.

Overall I think there is some slight merit to this popular assumption. Hair on the face at least that is shaved does appear to grow back thicker, even if the shaving alone isn't the cause. Although it clearly isn't true in all cases. For example I personally have a short haircut, and when I get it cut the back of my neck is shaved by the barber. If the idea of hair growing back thicker was totally true I would probably be in the process of developing a full blown lions mane by now, which of course I'm not, sadly.