The only scientific way to increase facial hair is to increase
the amount of testosterone in the bloodstream. A doctor could test
for testosterone insufficiency and prescribe injections, but there
is no guarantee. Side effects of testosterone injections include
increased aggressive behaviour and shrinkage of the
testicles.
Facial hair also increases with age, so waiting works too. Men from
some racial and genetic backgrounds have little or no facial hair
even with plenty of testosterone, so if all else fails, you might
wish to consider altering your DNA.
