Is my period late because of the morning-after pill or am I pregnant?
Taking the Julie Morning After Pill (or any emergency contraceptive with levonorgestrel) can temporarily change your period—making it come earlier, later, heavier, lighter, or causing spotting. This is one of the most common side effects, and your cycle should return to normal within a month or two. These changes don’t affect your long-term fertility. Other common side effects (usually within a day or two) are similar to period symptoms, like nausea, tiredness, lower belly pain, headache, dizziness, and breast tenderness. If your period is more than one week late after taking the pill, or three weeks have passed since you took it without bleeding, take a pregnancy test. If you have ongoing changes or concerning symptoms, check in with your healthcare provider.
Menstrual changes are the number one side effect of taking a morning-after pill, but a late period is especially concerning when you’re worried about pregnancy. After taking the Julie Morning After Pill™, Plan B® or other OTC morning-after pills, the average delay in a period is around seven days. Being prepared for a disruption in your cycle may help calm your nerves when waiting for your period, so we’re sharing everything you need to know about why it happens, how long it lasts and when it’s the optimal time to take a pregnancy test.
Can the Plan B Delay Your Period?
The morning-after pill, like Plan B and Julie, can temporarily affect your period. In fact, a change in your cycle is one of the most common reported side effects of the morning-after pill. That’s because it contains a higher dose of levonorgestrel (the main ingredient in the Julie Morning After Pill) compared to what’s found in birth control pills, so it’s likely to impact your body’s natural hormone levels for a short period of time. Waiting for your period to arrive can be stressful, especially after taking emergency contraception, but just know that it’s totally normal for your period to be delayed.
While we’re on the topic, your period might also be lighter or heavier than usual, or you could experience spotting in between cycles. Since factors like stress can also affect your menstrual cycle, this could make your period even later. If your period is more than one week late, it’s best to take a pregnancy test.
Why does the morning-after pill affect your period?
The morning-after pill, like Julie’s, is made up of a synthetic hormone called levonorgestrel, which stops or delays the timing of ovulation (when the ovary releases an egg). It’s a bit of a domino effect: Anytime you take a hormone, it will impact your hormone levels, which can in turn temporarily impact your period.
Our menstrual cycles are made up of four phases: menstrual, follicular, ovulatory, and luteal. Since the morning-after pill affects ovulation, a chain reaction can occur where the other stages of your cycle become impacted or temporarily delayed, which is why some people experience an early or a late period. However, this change is not permanent and your cycle should reset in the following month. This has no impact on your reproductive health or long-term fertility.
What are the morning-after pill side effects compared to typical period symptoms?
Not everyone who takes the morning-after pill will experience side effects, but those who do can expect them to be pretty similar to period symptoms. The majority of symptoms from levonorgestrel are usually felt within 24 hours of taking it. Common side effects include:
- Changes in your period
- Nausea
- Lower abdominal pain
- Tiredness
- Headache
- Dizziness
- Breast tenderness
These symptoms tend to subside within a day or two. Levonorgestrel is FDA-approved and proven to be safe when taken as directed.
Symptom | After taking the morning-after pill | Your period |
Period disruption | Spotting between periods, heavier or lighter flow, early or late period | N/A |
Nausea | Within 24 hours after taking pill | Begins two to three days before flow |
Lower abdominal pain/cramps | Within 24 hours after taking pill | Begin one to two days before flow and peak on day two of period |
Tiredness | Within 24 hours after taking pill | Begins two to three days before flow |
Headache | Within 24 hours after taking pill | Begins two to three days before flow |
Dizziness | Within 24 hours after taking pill | Not typical |
Breast tenderness | Within 24 hours after taking pill | Begins two to three days before flow |
How long does the morning-after pill disrupt your cycle?
Great news: typically just for one menstrual cycle! Most people notice that their period starts either a few days early or a few days late, though some people have reported a two-week delay in menstruation. However, a late period does not always mean pregnancy. If it’s been seven days after your expected period date, it’s best to take a pregnancy test.
Remember, changes to your cycle may be expected when taking the Julie Morning After Pill, but everything should return to normal within another cycle or two. If you’re still experiencing changes thereafter, consider discussing with your medical provider.
When should you take a pregnancy test?
We know that a delayed or missed period can be super stressful, but remember that there are many reasons why your period could be late. Don’t jump to conclusions!
As a general rule of thumb, it’s best to take a pregnancy test if:
- You’ve taken the morning-after pill and seven days have passed since you’d normally get your period.
- It’s been 3 weeks since you took the morning-after pill and your period still hasn’t come.
- 21 days have passed since the date of unprotected sex (pregnancy tests are usually the most accurate after three weeks).
- You had unprotected sex after taking the morning-after pill and didn’t use emergency contraception again (emergency contraception does not protect against future unprotected sex).
If you have other questions or concerns, or if you experience severe lower abdominal pain and/or persistent bleeding, contact your medical provider.
How late can a period be before I should take a pregnancy test? | If your period is more than a week late and you've had unprotected sex, take a pregnancy test. Home pregnancy tests are most accurate from the first day of your missed period onward. |
What causes a late period besides pregnancy? | A late period can be caused by stress, illness, sudden weight changes, excessive exercise, hormonal imbalances, thyroid issues, PCOS, or travel. If your cycle is consistently irregular, talk to a healthcare provider. |
What are the early signs of pregnancy? | Early pregnancy symptoms include a missed period, nausea, breast tenderness, fatigue, light spotting (implantation bleeding), and frequent urination. However, these symptoms can also have other causes. |
Can taking the morning-after pill delay my period? | Yes. Julie (levonorgestrel) can cause your period to come earlier or later than expected. If your period is more than a week late after taking Julie, take a pregnancy test to confirm. |
How accurate are home pregnancy tests? | Home pregnancy tests are highly accurate (over 99%) when taken correctly from the first day of a missed period. Testing too early may produce a false negative. For best results, use first-morning urine. |
While we love to share useful and helpful information, the above shouldn’t replace the advice of your healthcare professional. For questions about birth control and other women’s health issues, please talk to your doctor.
Julie wants to keep young women in the driver’s seat of their own stories and provide them with the tools necessary for a happy, healthy sex life.
We know (and have lived!) through the ups and downs of young adulthood firsthand, and we aim to normalize the events, conversations, and questions that come during this period to help destigmatize sexual health. We believe women should live life with total freedom — starting with their ability to choose how, when, and if they become pregnant.
We know that women can make the best choices for themselves when equipped with the right information. We don’t take sexual education lightly and are committed to sharing accurate and factual information through rigorous planning and QA processes. In fact, all Julie content is reviewed by at least two board-certified doctors on our medical board. Learn more about them here.
For more details on our editorial process, see here.
Tessa Commers, MD, FAAP, MS is a board-certified pediatrician based in the Seattle area with a particular interest in adolescent health and sexual education. In addition to clinical practice and serving as Head of Medical at Julie, Tessa also founded AskDoctorT — an education platform with over a million followers across Instagram, TikTok, and YouTube — aimed at improving adolescent health literacy and body confidence. She also hosted and wrote the puberty podcast “That’s Totally Normal!” and has contributed to peer-reviewed publications and educational initiatives focused on child and adolescent wellbeing.
Education: Children’s Mercy Hospital, Kansas City – Pediatric Residency; University of Nebraska Medical Center – Doctor of Medicine (MD); University of Nebraska Medical Center – Master of Science (MS, Genetics, Cell Biology and Anatomy); New York University – Bachelor of Arts (BA)
Dr. Jennifer M. Peña, MD, FACP, AAHIVS is a board-certified internal medicine physician and physician leader with more than 20 years of experience in primary care and women’s health. An Army combat veteran, Jennifer served in the White House Medical Unit under two presidential administrations, including as primary physician to the Vice President of the United States.
She also serves as chief medical officer, medical director, practice owner, and advisor to healthcare and health tech organizations across the U.S., the Caribbean, and beyond. Jennifer’s work in medicine includes appearances on CNN, BBC, MSNBC, Univisión, and more, as well as being named one of Business Insider’s “30 Leaders Under 40 Changing Healthcare” and Veteran of the Year by Latina Style magazine.
Education: Walter Reed Army Medical Center – Internal Medicine Residency; William Beaumont Army Medical Center – Internal Medicine Internship; University of Pittsburgh School of Medicine – Doctor of Medicine (MD); Yale University – Bachelor of Science (BS)
