It is false that if you have the same symptoms as a friend, it's acceptable to take their prescription medicine. This is not acceptable because even though your symptoms may seem the same, they may differ a bit, and you may not be suffering from the same disease. So taking their medicine may do quite the opposite of what a medicine is supposed to do, if you do not suffer from the same disease. So you should go see a doctor who will decide what medicine you should be taking.