The last week of birth control pills usually consists of inactive pills, which do not contain any hormones. They are sometimes called placebo pills or sugar pills. There are many different types of birth control pill.

One of the most common is the combination pill, which contains synthetic forms of the hormones estrogen and progesterone.

Different types and brands of the pill may include various amounts of placebo pills in their packs. Common types of combination pill packs include:

• 28-day pill packs: For most brands, the pills for the first 3 weeks of the pack contain the hormones, while those for the last 7 days do not contain any hormones at all. These pills are known as placebo pills, and they are there to help people make a habit of taking the pill regularly. Some newer pill brands use fewer placebo pills.
• 21-day pill packs: These pill packs contain 21 days of pills with active hormones. A person will then wait 7 days before starting a new pack, during which time they will not take any placebo pills.
• 91-day pill packs: Some types of pill contain 84 active pills and 7 inactive pills. People taking these pills should only get their period once every 3 months.