How to Start Birth Control Pills

The Logistics of Starting, Including When and How to Take Your First Pill

Many young people struggle with the question of when to start birth control, particularly when it comes to the birth control pill. Nearly 65% of American women ages 15–49 use contraception, and 13% of those rely on the pill.

Some people take the pill to prevent pregnancy, while others use it as medication to help with painful periods, migraines, or other medical conditions. 

Whether you’re sexually active and looking to avoid pregnancy or taking the pill for another reason, it’s important to know when to start birth control and when birth control starts working.

Any person with a period, no matter what their age, can use the pill to prevent pregnancy. You can start the pill at any point in your menstrual cycle. However, depending on when in your cycle you start it, the pill may not be effective for seven days. That means you may need to use backup birth control, like condoms, during that time.

This article will explain when it's all right to start birth control and when it will become effective once you do begin taking it.

Woman taking birth control

Mindful Media / E+/ Getty Images

How It Works

The pill prevents pregnancy by stopping ovulation. At the same time, the pill thickens the mucus of the cervix, which makes it difficult for sperm to get past the cervix and into the fallopian tubes, where fertilization occurs.

When taken exactly as directed—meaning every day at the same general time, without fail—the pill is 99% effective at preventing pregnancy. Because no one is perfect, the real-life efficacy of the pill is estimated to be about 91%.

There are two types of birth control pills:

  • Combination pills are the most common. They contain the hormones estrogen and progestin.
  • Minipills contain only progestin.  

In order for the pill to be most effective, it must be taken at the same time every day. This is particularly essential for the progestin-only (minipill) to work.

If you miss a birth control pill, you should take it as soon as you notice. If you miss more than one combination pill, you may be at risk for unplanned pregnancy. If a progestin-only pill (minipill) is taken more than three hours late or missed on any given day, you should use backup contraception, like condoms, or abstain from sex for at least two days to avoid getting pregnant.

When you start birth control, decide when to take the pill each day, and stick with that schedule. Setting a daily alarm or calendar reminder on your cellphone can help you remember.

Age and Birth Control

Since the birth control pill works by preventing ovulation, it can be used once a person begins ovulating. A person ovulates for the first time before they have their first period. Studies have shown that the pill is very safe for teenagers, so even young teens can choose to start the pill if they are sexually active or have another medical reason.

Although the pill is safe for very young teens, it can be difficult for younger people to remember to take a pill at the same time every day. Because of this, the Centers for Disease Control and Prevention (CDC) recommends long-acting reversible contraception (LARC), like the implant or intrauterine devices (IUDs), as the most effective birth control for teens. The risk of pregnancy among teens is less than 1% when using LARC compared to 9% when using the pill. 

According to the CDC, contraception is needed until age 44 if a woman wants to avoid pregnancy, as it is rare to become pregnant after that age. However, people over age 44 do still get pregnant. The American College of Obstetricians and Gynecologists and the North American Menopause Society (NAMS) both recommend that women continue contraceptive use until menopause or age 50–55 years.

How to Start

It’s best to start taking the birth control pill as soon as it is prescribed to you. Studies have shown that delaying the start of taking the pill can increase the risk for unplanned pregnancy.

However, the type of pill and where you are in your menstrual cycle will determine when the pill becomes effective at preventing pregnancy. 

Starting Combination Pills

  • If you begin taking the pill within five days of the start of your period, you are protected from pregnancy right away, and you do not need to use backup birth control.
  • If you begin the pill at any other point in your cycle, it will take seven days to become effective. Use backup birth control like a condom for those seven days.
  • Combination pills can be started six weeks after giving birth for breastfeeding people, and three weeks after giving birth for people who are not breastfeeding.
  • Combination pills can be used immediately after an abortion or miscarriage.

Starting the Minipill

  • The minipill is effective after two days, no matter when in your cycle you start it. For the first two days, use backup birth control like condoms.
  • The minipill can be used immediately after giving birth, having an abortion, or miscarrying.

Side Effects

For teens, the side effects of the birth control pill are generally very mild and are less severe than the risk and side effects of pregnancy.

For all people, the side effects of the pill include:

  • Changes to the menstrual cycle or spotting
  • Nausea
  • Mood swings
  • Migraines
  • Breast tenderness or weight gain 

In rare cases, the birth control pill can cause blood clots, heart attack, high blood pressure, and stroke, particularly among people who smoke. Before starting birth control, talk to your doctor about the side effects. 

If You Miss a Pill

The pill is 99% effective if it’s taken at the same time every single day. If you miss a pill, your risk for pregnancy is increased. 

Taking your pill at the same time is particularly important if you’re on the minipill, which relies on a smaller dose of hormones to prevent pregnancy. The minipill becomes less effective if you take it more than three hours later than your regular time. If that happens, you should use backup birth control for two days.

Here’s what you should do if you miss a combination pill. In all cases, your risk for pregnancy is increased, so you should use a backup form of birth control for at least seven days. 

  • If you miss one pill, take it as soon as you notice.
  • If you miss two, take the most recent missed pill as soon as possible, then resume taking the remaining pills at your usual time (even if it means taking two pills on the same day). Use backup contraception or avoid intercourse for seven days.
  • If you miss three or more, throw out the pack and restart with a new pack. Use backup birth control for at least seven days.

Consider emergency contraception if two or more hormonal pills were missed during the first week and unprotected sexual intercourse occurred in the previous five days.

A Word From Verywell

Starting birth control is a very personal choice. You should talk with your healthcare provider about whether taking the pill is right for you and when you should start the pill. Consider including your sexual partner in this conversation. 

Once you’ve been prescribed the pill, you should begin taking it right away. Just remember to use backup contraception for 48 hours on the minipill and seven days on the combination pill unless you started the combination pill within the first five days of your cycle. 

Remember that the birth control pill is only one form of contraception. Other forms, like the implant and IUDs, are discreet and highly effective for a longer period of time, so they’re often a good choice for young people.

Ultimately, the right contraceptive is the one that works well with your body and lifestyle. No matter what contraceptive you use, remember that condoms are the only way to prevent the spread of sexually transmitted infections (STIs).

Frequently Asked Questions

  • When does birth control start working?

    If you are taking a minipill, it becomes effective within 48 hours, no matter when in your cycle you start it. If you start a combination pill within five days of starting your period, it is effective immediately. If you start it at any other point in your cycle, it will not be effective at preventing pregnancy for seven days, and you should use backup birth control during that time.

  • What’s the best time of day to take birth control?

    The best time of day to take birth control is the time that you will consistently remember. Some people like to take it in the morning, others at bedtime. Just remember that you need to stick to a specific time even on weekends. Consider setting an alarm to remind yourself to take the pill at the same time daily.

  • When do you get your period on birth control?

    Most birth control pill packs are set up for a 28-day cycle. Combination pills have 21 active pills, which contain hormones, and seven sugar pills, which have no active ingredients. Most people get their period during the week of sugar pills. Minipills contain hormones in every dose, which can lead to slightly irregular periods.

  • Do you have to take birth control at the same time every day?

    Yes. You must take the birth control pill at the same time each day to have the most protection from pregnancy. This is especially important for the minipill. If you miss your regular time by more than three hours while on the minipill, use backup birth control for 48 hours.

  • How does birth control affect your period in the first month?

    Birth control can help regulate your period, beginning the first month you take it. If you take the minipill starting at the beginning of your cycle, you’ll likely get your period four weeks later. If you take a combination pill, you can expect your period to begin shortly after switching to the inactive pills, which are usually a different color.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Current contraceptive status among women aged 15–49: United States, 2015–2017.

  2. Planned Parenthood. How do I use the birth control pill?

  3. Planned Parenthood. How effective is the birth control pill.

  4. Committee on Adolescent Health Care. Committee opinion no 699: adolescent pregnancy, contraception, and sexual activity. Obstet Gynecol. 129(5):e142-e149. doi:10.1097/AOG.0000000000002045

  5. Centers for Disease Control and Prevention. Few teens use the most effective types of birth control.

  6. Centers for Disease Control and Prevention. When can women stop using contraceptives.

  7. Lesnewski R. Initiating hormonal contraceptionAm Fam Physician. 103(5):291-300.

  8. MedlinePlus. Birth control pills.

By Kelly Burch
Kelly Burch is has written about health topics for more than a decade. Her writing has appeared in The Washington Post, The Chicago Tribune, and more.