Strictly speaking, giving out prescription drug without a MD's prescription is a criminal offence, punishable by prison term. I have heard people get in trouble for this in US, but not Canada.
Abusing anti-biotic is a very serious matter, you are putting not just yourself, but the whole society at risk: strong antibiotic-resistant germ can develop inside your body, then infect others.
American Medical Association issued a guideline early this year, it recommends against giving antibiotic, even to people who has 104F(40C) high fever.