Are you considering starting or switching birth control pills? If so, your doctor should be able to answer any questions you have regarding which birth control options are safe for you and what options may best suit your needs. If you decide you want to take birth control pills, you’ll need to figure out when you can start. We’ll discuss your options and what experts say about them here.

Birth Control Basics

Birth control pills contain synthetic hormones that work to prevent pregnancy. These hormones can stop ovulation and make it more difficult for sperm to enter your uterus. They can also alter your uterine lining, which can reduce the likelihood of implantation.

Over the past decade, birth control options have increased significantly. When birth control pills were first introduced in 1960, women would take 21 pills of active hormones with seven placebo pills. These reminder pills would allow for bleeding similar to a regular menstrual period.

There are now more brands of birth control pills to choose from, and there are also different regimens. Some packs have 24 days of active pills and four days of placebos. Others contain all active pills and no placebos. These pills make up an extended-cycle, or continuous, regimen. This level of hormones can either shorten how many periods you have or eliminate your periods altogether.

You’ll want to discuss these options with your doctor, as every birth control option isn’t right for every woman. When they’re taken correctly, birth control pills are up to 99 percent effective. Keep reading for more on how to ensure that accuracy.

How and When to Start Your Pill Pack

Once you have your birth control pack, you may want to start right away. Before you swallow that first pill, there are some things to note. First, look at what type of pill it is.

For combination pills, or pills that contain both estrogen and progestin, Sherry Ross, M.D., OB-GYN, and women’s health expert in Los Angeles, likes to recommend starting the pack on the first day of your period.

“This gives you protection against getting pregnant that month and reduces the likelihood of irregular bleeding,” she says.

If you take your first pill within five days of your period, you’re protected immediately.

However, if you want to start sooner and your period isn’t for a few weeks, you can still begin taking your birth control pills, but you won’t be protected right away.

If you start the pill pack midcycle, you’ll need backup birth control, Ross says. That means you should use condoms or another form of birth control during your first week of starting birth control pills. After one week, the pills will protect against pregnancy.

You can also start progestin-only pills midcycle. You’ll want to have a backup method in place for the first two days. After those two days, your birth control pills should be able to provide protection against pregnancy.

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Side Effects to Starting Midcycle

Because the pill is meant to mimic your menstrual cycle while preventing ovulation, Ross says starting the pill on the first day of your cycle or the first Sunday after your cycle starts is recommended.

When you start midcycle, you’re quite literally going against your body’s natural hormonal rhythm. Because of this, you may experience irregular bleeding while your body adjusts.

This irregular bleeding, or spotting, is almost a given during your first pack, but it could linger as long as a couple of months. Be sure to plan accordingly.

Are There Benefits to Starting Midcycle?

Although there’s no health benefit to starting your birth control midcycle, there are some benefits to starting birth control sooner. It mostly comes down to convenience.

Starting right away might make more sense for you if you’re more likely to forget your doctor’s instructions for how to take the pill by the time your next period rolls around. You may even want to skip your next period, which would affect when you start your pills.

If you want to delay or even skip your next period, starting midcycle might make more sense for you, says Fahimeh Sasan, D.O., assistant professor of obstetrics, gynecology and reproductive science, Icahn School of Medicine at Mount Sinai.

Just know you’re not protected immediately and take the necessary precautions.

Risk Factors to Consider

According to Ross, any potential benefits are outweighed by the side effects that can come with starting midcycle.

“If you do so, you will definitely be out of sync with the pill pack and have irregular bleeding,” she says.

Because the hormone levels of the pill pack are meant to coincide with your natural monthly cycle, how much you stray from your normal monthly cycle will affect how well you adjust to adding more hormones into your system at exactly the wrong times.

“The only reason for a woman to start the birth control midcycle is if she is already having irregular periods and wants to regulate her cycle or if she is eager to get started on contraception,” Ross says.

Staying on Track

Birth control pills are incredibly effective but only if they’re taken correctly. That means following all directions from your doctor and taking them at the same time every day.

“The birth control pill must be taken daily in order for it to work,” Sasan says. “The most common reason women will have birth control failure is that they were not taking the pill correctly on a daily basis.”

If you decide to start midcycle, make sure you know when pregnancy protection starts. It’s not immediate, and it varies by pill type. If this is worrisome, you may want to reconsider starting the pack at the beginning of your period. Otherwise, stock up on backup contraceptives for any potential sexual activity you may have before the pill’s protection kicks in.

The National Women’s Health Resource Center offers a few other tips to make sure your pill is working sufficiently. First, never skip pills, even if you’re not having sex. Second, understand that diarrhea or vomiting can affect the absorption of the pill. Certain antibiotics can alter their effectiveness, too. If either of these apply to you, contact your doctor to find out the next steps to avoid an accidental pregnancy. When in doubt, use backup contraception.

Deciding on the Right Birth Control for You

Not all birth control options are right for every woman, so be sure to talk with your doctor about the details of your medical history. You should also take your lifestyle into consideration. If you know you can be forgetful or that you may have difficulty taking a pill every day, this pill may not be the best option for you.

If you’ve recently been pregnant or are currently breast-feeding, you’ll want to talk to your doctor as well. Your doctor might prescribe a progestin-only pill or ask you to wait to take a combination pack.

If you’re concerned about the potential side effects of birth control, such as breast tenderness, bloating, or mood issues, there are other options available.

Deciding which birth control to use and how to start are questions that your doctor can help you answer while keeping your individual circumstances in mind. No matter what questions you have, there’s at least one birth control option that can work for you.

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