t take 2-3 months to start working if you take it as directed, although initial
side effects (like
spotting or nausea) may take that long to resolve. The pill is effective after 7 days of taking it properly.
OP: The detailed labeling for the one I take (Altavera) says that with one missed pill, if you take it when you remember and then keep your schedule, doesn't require any backup method, but missing more than one does.