Question: how do 28 day birth control pills work?
Answer: Take 1 pill every day for 28 days (four weeks) in a row, and then start a new pack on day 29. The last pills in 28-day packs of combination pills do not have hormones in them. These pills are called "reminder" or “placebo” pills — they help remind you to take your pill every day and start your next pack on time.