Opill (norgestrel) is a brand-name birth control pill that’s taken to help prevent pregnancy. It’s available over the counter. As with other drugs, Opill can cause side effects, such as headache and changes in your periods.

Note: Opill is FDA-approved but is not yet available for purchase. The drug’s manufacturer expects Opill to be available over the counter in early 2024. For more information, talk with your doctor or pharmacist.

Opill can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took Opill in clinical trials:

  • changes in periods*
  • headache
  • nausea
  • abdominal pain, cramps, or bloating

* For more information about this side effect, see “Side effect specifics” below.

Mild side effects can occur with Opill. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Opill’s label information.

Mild side effects that have been reported with Opill include:

  • changes in periods*
  • headache
  • backache
  • breast tenderness
  • abdominal pain, cramps, or bloating
  • nausea
  • dizziness
  • increased appetite
  • fatigue
  • acne
  • vaginal discharge
  • nervousness
  • mild allergic reaction†

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you develop a side effect while taking Opill and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Side effect specifics” below.
† An allergic reaction is possible after taking Opill. However, it’s not clear whether this side effect occurred in clinical trials. To learn more, see the “Side effect specifics” section below.

Opill may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Opill’s label information.

If you develop serious side effects while taking Opill, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported and their symptoms include:

* For more information about this side effect, see “Side effect specifics” below.
† An allergic reaction is possible after taking Opill. However, it’s not clear whether this side effect occurred in clinical trials. To learn more, see the “Side effect specifics” section below.

Learn more about some of the side effects that Opill may cause. To find out how often side effects occurred in clinical trials, see the label information for Opill.

Changes in periods

Opill can cause changes in menstrual periods. These changes can include:

  • irregular periods
  • periods that are heavier or lighter than is typical for you
  • spotting or bleeding between periods
  • stopping of periods

In clinical trials, period changes were common with Opill. Period changes often settle after a few months of taking Opill.

You’re more likely to have irregular periods or spotting between periods if you don’t have a steady level of Opill in your body. This can happen if you don’t take Opill regularly at the same time every day or if you miss doses of Opill. It can also happen if you vomit or have severe diarrhea in the 4 hours after taking Opill. Taking certain medications or supplements with Opill can also cause this problem.

If any of these things happen, Opill may also be less effective at helping to prevent pregnancy.

What you can do

You should try to take Opill at the same time every day, even if you have bleeding. This allows the medication to work effectively and helps avoid irregular bleeding and spotting.

While taking Opill, talk with your doctor if your period becomes unusually heavy or lasts longer than 8 days. You should also talk with your doctor if you frequently have bleeding during sex. Your doctor may recommend a medical examination to check for any problems. They may also recommend switching to a different form of birth control.

If your period is late after missing Opill doses, or you miss more than two periods in a row, you should do a pregnancy test and talk with your doctor.

Ovarian cysts

Opill can sometimes cause ovarian cysts, which are small fluid-filled sacs that develop on the ovaries. This side effect wasn’t commonly reported in clinical trials of Opill.

Ovarian cysts may not cause any symptoms and often go away on their own. But they may sometimes cause symptoms such as:

  • abdominal pain or bloating
  • pelvic pain before or during your period
  • pain in your lower back or upper thighs
  • pain during sex
  • nausea and vomiting
  • frequent urges to urinate or pass a bowel movement

In rare cases, an ovarian cyst may rupture, become infected, or cause ovarian torsion (twisted ovary). This can cause symptoms such as:

  • sudden, severe abdominal pain or pressure
  • heavy vaginal bleeding
  • fever
  • faintness or dizziness
  • rapid breathing

What you can do

If you have symptoms of ovarian cysts while taking Opill, contact your doctor. They may recommend a pelvic exam or ultrasound to investigate the cause of your symptoms.

If you have symptoms of a ruptured or infected cyst or ovarian torsion, this is a medical emergency. Go to your local emergency department or call 911 right away.

Allergic reaction

As with most drugs, Opill can cause an allergic reaction in some people. However, It’s not clear whether this side effect occurred in clinical trials.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking Opill. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Be sure to talk with your doctor about your health history before you take Opill. This drug may not be the right treatment option for you if you have certain medical conditions or other factors that affect your health. These are considered drug-condition or drug-factor interactions. The conditions and factors to consider include:

Breast cancer: If you’ve ever had breast cancer, your doctor will likely recommend that you do not take Opill. Opill could make your breast cancer get worse or come back. Talk with your doctor about other forms of birth control that may be better options for you.

Other hormone-sensitive cancer: If you’ve ever had cancer sensitive to progestin hormones, your doctor will likely recommend that you do not take Opill. Opill could make your cancer get worse or come back. Talk with your doctor about other forms of birth control that may be better options for you.

Liver problems, including liver cancer: If you have liver problems, Opill could make them worse. Talk with your doctor about whether Opill is right for you. If you have liver cancer, your doctor will likely recommend that you do not take Opill. Talk with your doctor about other forms of birth control that may be better options for you.

Unusual vaginal bleeding: If you have any unusual vaginal bleeding, tell your doctor before taking Opill. Your doctor may recommend a pelvic or ultrasound examination to help diagnose the cause of any unusual bleeding. This can help determine whether Opill is a good option for you.

Allergic reaction: If you’ve had an allergic reaction to Opill or any of its ingredients, including Yellow No. 5 (tartrazine), your doctor will likely recommend that you do not take Opill. (If you’ve had an allergic reaction to aspirin in the past, you may also have an allergic reaction to tartrazine.) Ask your doctor what other medications may be better options for you.

Migraine: If you have migraine episodes, Taking Opill could make them worse or more frequent. Talk with your doctor before taking Opill. Other forms of birth control may be better options for you.

Other hormonal birth control: If you use other hormonal forms of birth control, such as the combined pill, patch, vaginal ring, implant, injection, or IUD, you should not take Opill as well. Doing so could raise your risk of side effects.

Pregnancy: Opill is taken to help prevent pregnancy. If you’re pregnant or think you could be pregnant, you should not take Opill. If you’ve had sex without a condom or other barrier method, you should not take Opill to try and prevent pregnancy. Opill will not work as an emergency contraceptive (morning-after pill).

Breastfeeding:If you’re breastfeeding your child, Opill should be safe for you to take. However, you should still talk with your doctor about the possible effects of Opill while you’re breastfeeding.

Alcohol consumption: If you drink alcohol, Opill is likely safe for you. Alcohol doesn’t interact with Opill.

If you’d like to learn more about Opill, talk with your doctor or pharmacist. They can help answer any questions you have about side effects from taking the drug.

Besides talking with your doctor, you can do some research on your own. These articles might help:

  • More information about Opill: For details about other aspects of Opill, refer to this article.
  • Dosage: For information about the dosage of Opill, view this article.
  • Interactions: To find out about Opill’s interactions, see this article.
  • A look at pregnancy prevention: For details about pregnancy prevention, see our pregnancy and parenthood hub.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.