How to increase height after 18?

You cannot: you may still grow a bit and take good nutrition and a daily vitamin but a lot of it is genetic--so do not worry too muchj.

Done puberty?: At 18 yrs old, I image that you have reached full maturity; however, as a male you may still have a little bit of height growth to go. Live a healthy lifestyle - you will be as tall as your genes dictate. Unless you have a growth hormone deficiency, there is not much to be done at this point. See your doctor for an evaluation to determine if you have, indeed, reached your adult height.

Platform shoes: The growth centers of most males will close by age 18 although a few will grow a little longer.By 20, the growth centers have closed and you are done. If you wish, an x-ray of your hand could identify any additional growth potential.Good diet, exercise and proper rest allows you to reach your maximum height.

Stature: Is inherited and you can't increase it if you are healthy.