Although Nick Jonas and Zac Efron used to be tween idols, both stars have matured into adult careers. No worries, both men have retained their heartthrob status! Which singer/actor is more swoon-worthy?

Zac Efron is a long way from his 'High School Musical' days. The actor continues to push himself, starring in a variety of projects. Anyone who wants to see him smolder only needs to watch 'The Lucky One,' a romantic drama based on a Nicholas Sparks movie. Zac has also received numerous nods from People's Most Beautiful list. Not too shabby!

Nick Jonas also has us "burning up." The singer recently posted a shirtless selfie that sent fans into a tizzy -- and for good reason. His healthy lifestyle is clearly paying off! Additionally, Nick is involved in multiple philanthropies, including promoting research funding for diabetes. We love a guy who gives back!

Which of these stars makes you flustered? Vote in the poll below!

Zac Efron

Stephen Lovekin, Getty Images

Nick Jonas

Monica Schipper, Getty Images