Prince William - Top Hair Expert Warns Prince William He'll Be Bald At 40

Pop idol Justin Bieber recently sparked controversy when he poked fun at the prince and suggested he should try taking hair loss drug Propecia to stave off baldness, which has blighted the males in his family, but Dr. Asim Shahmalak insists the heir to the throne's receding hairline is no laughing matter.

He suggests Propecia could halt the royal's problem, but it would not restore his lost hair.

Shahmalak, who runs the Crown Clinic in Manchester, England, tells WENN, "He would have to take Propecia for the rest of his life and it would not help him to grow new hair."

And he doesn't think Bieber's idea is a great one: "Around two per cent of patients who take Propecia suffer side effects,

such as the loss of libido."

But the hair doctor has urged the prince to do something or risk becoming completely bald on the top of his head by the age of 40.

He adds, "Prince William has been losing his hair since he was 25. His hair loss is even worse than his father's, and obviously his grandfather Philip is bald too. That is a strong family gene.

"Prince William has quite fine light brown hair. To restore the hair on the top of his head to a reasonable level of density, he will need at least 3,000 or 4,000 hair grafts where hair is taken from the back of the scalp and moved to the top of the head. This is similar to the treatment which (British soccer player) Wayne Rooney had."