Lots of men struggle with growing beards and become frustrated with patchy growth that never moves past heavy stubble. In most cases, the lack of growth is linked to testosterone levels. Specifically, testosterone contains a steroid called dihydrotestosterone, or DHT. DHT can have an adverse effect on head hair because it builds up in the hair follicles over time and leads to baldness. But it doesn’t have this effect on beard hair. This is why you may see a bald man with a full, bushy beard.