How to increase height?.i am 18 yrs old now..

Cross your fingers: There's no good way for the average person to purposefully increase his/her height short of going through puberty while getting enough healthy calories. However, in those w/proven short stature & open epiphyses, growth hormone may help. But if your growth plates are closed, then growth hormone won't make you any taller. So start by first getting an xray of your hand to evaluate those growth plates.