Hi, that product has about an 85% success rate at preventing pregnancy when taken correctly. And that means following the directions to a T. If it says to take two tabs on the instructions, TAKE the two tabs!!!! The difference of postinor 1 versus postinor 2 is that the 2 takes TWO pills. So, ya, you should take it. But again, read the instructions. Know that this isn't the first choice for many doctors for emergency contraception. It's not quite as effective and has a fair number of side effects. Your period likely will be late after this. Take a pregnancy test 2.5 weeks after the sex you had to make sure it worked. good luck