Since 1998, the drug Viagra had been prescribed to more than 23 million men worldwide to help them treat erectile dysfunction. And is expected of any drug that treats one aspect of our body, it changes others. So far, Viagra has led to some men experiencing vision and hearing problems. Now a new study in the Journal of the American Medicine Association is associating Viagra use with higher risk of melanoma, a type of skin cancer. So, should men worry? Dr George Lee helps us understand.