Opill (norgestrel) is an over-the-counter oral birth control pill. Opill can cause side effects that range from mild to serious. Examples include irregular periods, headache, and nausea.

The Food and Drug Administration (FDA) has approved Opill for pregnancy prevention in females* who are able to become pregnant. The drug is not yet available, but the manufacturer expects it to be on the market in early 2024.

Opill is not approved for use as an emergency contraceptive and will not protect against sexually transmitted diseases.

Opill comes as an oral tablet and contains the active ingredient norgestrel. (An active ingredient is what makes a drug work.)

Keep reading to learn about the common, mild, and serious side effects Opill can cause. For a general overview of the drug, including details about its uses, see this article.

* In this article, we use the term “female” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.

Some people may experience mild to serious side effects during their Opill treatment. Examples of the drug’s commonly reported side effects include:

These are just a few of the more common side effects Opill can cause. And they won’t occur in everyone who takes this medication. Keep reading to learn more about mild to serious side effects of Opill.

* To learn more about this side effect, see the “Side effects explained” section below.

Mild side effects have been reported with Opill. These include:

In most cases, these side effects should be temporary. And some may be easily managed with home remedies or over-the-counter medications. But if you have symptoms that are ongoing or bothersome, talk with your doctor or pharmacist.

Opill may cause mild side effects other than those listed above. See the drug’s patient information leaflet for details.

* To learn more about this side effect, see the “Side effects explained” section below.

Serious side effects have been reported with Opill. These include:

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.

* To learn more about this side effect, see the “Side effects explained” section below.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Opill, visit MedWatch.

Get answers to some frequently asked questions about Opill’s side effects.

How do side effects of Opill compare with those of other birth control pills, such as Camila?

Opill and Camila are both birth control pills without estrogen. However, Camila requires a prescription, and Opill is an over-the-counter medication.

Opill’s active ingredient* is norgestrel, and Camila’s is norethindrone. Both are progestins.

All progestin-only birth control pills have similar side effects. These include:

  • headache
  • acne
  • breast tenderness
  • dizziness
  • fatigue (low energy)
  • irregular periods

* An active ingredient is what makes a drug work.

Does Opill cause long-term side effects?

It’s possible. Long-term side effects include those that may start at any time you’re taking a drug, even if you’ve taken it for a long time. It also includes side effects that may not go away even after you stop taking the drug.

Examples of long-term side effects that may occur with Opill include:

  • irregular periods*
  • acne
  • ovarian cyst*
  • liver problems

If you’re concerned about possible long-term side effects from Opill, talk with your doctor or pharmacist.

* To learn more about this side effect, see the “Side effects explained” section just below.

Learn more about some of the side effects Opill may cause.

Ovarian cyst

The growth of an ovarian cyst is a potential side effect of Opill. This drug stops the release of an egg and its fluid from the ovary, leading to the formation of a cyst. Because Opill continues to prevent fluid release, the cyst can gradually increase in size.

Most of the time, an ovarian cyst does not cause symptoms, but sometimes a cyst may cause:

  • uterus pain before or during your period
  • menstrual cycle changes
  • abdominal pain or bloating
  • vaginal bleeding
  • quickly feeling full while eating
  • lower back or upper thigh ache
  • painful intercourse
  • nausea and vomiting
  • painful or urgent bowel movements
  • frequent urges to urinate
  • breast tenderness

Factors that can increase the risk of an ovarian cyst when taking this drug include:

What might help

Work with your doctor to help catch the formation of cysts in the early stages. You can do this by discussing your risks, reporting your symptoms, and scheduling preventive wellness checks with them. Early identification of an ovarian cyst during Opill treatment is essential to avoid serious side effects such as:

  • ruptured cyst, which can cause heavy bleeding and sudden, severe pain
  • twisted ovary, which can cause severe abdominal pain and pressure
  • infected cyst, which can cause fever, night sweats, and severe pain
  • excessive blood loss, which can lead to nausea, vomiting, weakness, and shortness of breath

A ruptured or infected cyst, twisted ovary, or excessive blood loss is a medical emergency. If you experience any of these serious side effects, seek medical care immediately or call 911 or your local emergency number.

Irregular period

Irregular periods were a common side effect reported in studies of Opill. Irregular periods can be described as:

  • no period
  • spotting
  • light or short periods
  • bleeding between periods
  • heavy bleeding for a short or long time

Irregular periods can cause symptoms such as:

  • dizziness
  • fatigue (low energy)
  • skin that is paler than usual
  • nausea
  • vomiting
  • shortness of breath

Excessive bleeding from irregular periods may lead to iron-deficiency anemia.

Factors that can increase the risk of irregular periods when taking Opill include:

  • taking doses at changing times of the day
  • missing doses
  • taking medications that may reduce the effectiveness of Opill
  • vomiting or diarrhea within 4 hours of taking a dose

What might help

If you have irregular periods while taking this drug, try to take the tablets at the same time every day and avoid missing doses. It may take time for your monthly cycle to regulate. But if you miss two periods, take a pregnancy test and contact your doctor.

Talk with your doctor right away if you have any of the following:

  • bleeding lasting longer than 8 days
  • frequent bleeding with sex
  • an unusually heavy period

They’ll likely recommend a medical examination and suggest a different birth control option.

Allergic reaction

Like most drugs, Opill can cause an allergic reaction in some people. Symptoms can be mild to serious and can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin (usually in your eyelids, lips, hands, or feet)
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

In addition, Opill contains FD&C Yellow No. 5 (tartrazine). This can lead to allergy-like reactions, such as bronchial asthma, in some people. While FD&C Yellow No. 5 doesn’t affect many people, those sensitive to it may also be allergic to aspirin.

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms. Examples include:

  • an oral antihistamine, such as Benadryl (diphenhydramine)
  • a product you apply to your skin, such as hydrocortisone cream

If your doctor confirms you’ve had a mild allergic reaction to Opill, they’ll decide whether you should continue taking it.

If you have symptoms of a severe allergic reaction, such as swelling or difficulty breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to Opill, they may have you switch to a different treatment.

Keeping track of side effects

During your Opill treatment, consider taking notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you first start taking a new drug or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were taking when you had the side effect
  • how soon you had the side effect after starting that dose
  • what your symptoms were
  • how your symptoms affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Keeping notes and sharing them with your doctor will help them learn more about how Opill affects you. They can use this information to help adjust your treatment plan if needed.

Below is important information you should consider before starting Opill.

Warnings

Opill can sometimes cause harmful effects in people with certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether this drug is a good treatment option for you. Talk with your doctor about your health history before starting Opill. Be sure to tell them if any of the following factors apply to you:

* Opill belongs to the progestin group of birth control pills.

Alcohol and Opill

There are no known interactions between alcohol and Opill. If you have questions about consuming alcohol during Opill treatment, talk with your doctor or pharmacist.

Pregnancy and breastfeeding with Opill

If you’re able to become pregnant or breastfeed a child, consider the following information.

Pregnancy

Since there’s no need for pregnancy prevention in someone who’s already pregnant, Opill is not prescribed for pregnant people.

And although studies show that taking progestin-containing birth control pills during pregnancy won’t harm fetal development, it does increase the risk of an ectopic pregnancy. (This is when a fertilized egg doesn’t implant inside the uterus as it usually would.)

Be sure to talk with your doctor if you have a history of ectopic pregnancy before starting this medication.

Breastfeeding

Opill is considered safe to take while breastfeeding. Most doctors recommend progestin-only* birth control during breastfeeding because it does not contain estrogen. But if you’re breastfeeding or planning to do so, you should still talk with your doctor before starting Opill treatment.

* Opill is in the progestin-only group of birth control pills.

Like most drugs, Opill can cause a number of side effects that range from mild to serious. But most are temporary and go away after a few days to weeks. If you have questions about side effects that Opill can cause, talk with your doctor. Examples of questions to help get you started include:

  • What should I do if Opill causes me to throw up after I take a dose?
  • Will I gain weight while taking Opill?
  • Can Opill cause a blood clot, especially if I smoke tobacco?
  • How long will it take for irregular bleeding from Opill to stop?
  • Is it safe to take over-the-counter cramp pills to treat abdominal pain and bloating caused by Opill?
  • What side effects of Opill should prompt me to call you?

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Disclaimer: Healthline 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.