How dangerous generic Viagra could be?

Hi folks
generic viagra is being sold very cheap on the internet and it is available without a prescription. Has anyone experienced any side effects? I always use genuine medicine but was just wondering what are the experiences of people using generic versions of the medicine.
cheers
generic viagra is being sold very cheap on the internet and it is available without a prescription. Has anyone experienced any side effects? I always use genuine medicine but was just wondering what are the experiences of people using generic versions of the medicine.
cheers