Disclaimer: None of the information in this article constitutes medical advice. All statements are merely the opinion of the writer(s). We recommend that patients follow their doctor’s guidance in regard to birth control.
Opill is the first FDA-approved birth control medication that’s available over-the-counter (OTC). The generic name for Opill is norgestrel, and we’ll use these terms interchangeably throughout this article.
But is Opill proven to work? How does its effectiveness at preventing pregnancy compare to other birth control methods? Is the drug dangerous? And how does it actually work?
In this article we’ll answer all of these questions and more as we analyze clinical studies on Opill to determine if the drug is effective, and how its efficacy compares to other birth control methods.
We’ll discuss side effects of the medication, and explain how it works.
Is Opill Proven to Work?
A clinical trial published in the Contraception journal found Opill to be effective at reducing fertility, even during ovulation.
A 2022 clinical trial reported similar results: “During 28 days of exposure to [Opill], most women had no evidence of ovulation.”
However it’s worth noting that the above-linked study only had 52 participants which is a relatively small sample size.
Even when patients forget to take the pill, it may still be effective according to a 2023 clinical trial, which found that "forgetting to take [Opill] for one day…may not jeopardize contraceptive efficacy.”
This is an important consideration for an oral contraceptive, given that human error and noncompliance (forgetting to regularly take the pill) is one of the leading causes of birth control failure, as we documented in our article on another birth control medication called Lo Loestrin Fe.
Overall, Opill appears likely to be effective at preventing unintended pregnancies, which is unsurprising given that the drug was approved by the FDA for that purpose.
The FDA's Opill information resource page states that the drug must be taken at the same time every day for maximum effectiveness.
But how does its effectiveness compare to other birth control methods? We’ll answer that question in the next section.
Opill vs. Other Birth Control Methods
We can’t find any long-term clinical trials that reported on the pregnancy rates of women taking Opill.
However, if we assume Opill’s effectiveness to be similar to other oral contraceptives, it may be an inferior option to long-acting reversible contraceptive (LARC) methods like IUDs.
A 2015 medical review documented that LARC birth control methods were around 20x more effective on average than oral birth control. Because these devices are implanted into the body, absorption and user error are less of an issue.
For women focused on effectiveness over convenience, it may be best to speak with your doctor about LARC birth control options.
As we documented in our review of Yaz birth control, failure rates from oral contraceptives with “typical use” are clinically shown to be as high as 8%. Typical use includes occasional noncompliance (forgetting to take the pill once in a while).
But does Opill cause side effects? We’ll discuss in the next section.
Does Opill Cause Side Effects?
Oral contraceptives in the same class as Opill are clinically shown to cause changes in weight and changes in mood in some patients.
More major side effects relate to the cardiovascular system according to the above-linked review.
The FDA label for Opill lists changes in menstrual bleeding patterns, ovarian cysts, headache, dizziness and nausea all to be potential side effects of the drug.
It’s important to note that the FDA label does not carry a black box warning, which is a good sign about the safety profile of Opill. Drugs with potentially life-threatening side effects are required to publish this warning on the medication label.
Opill has a more favorable safety profile than the average birth control drug we've reviewed on Illuminate Health.
Opill in the Media
A segment on CNN is only three minutes long and discusses the FDA's approval of Opill and some of the public health implications:
A YouTube video from a local San Francisco news station interviewed people about their reactions to the first OTC birth control medication:
How Does Opill Work?
Opill has several mechanisms of action.
First, the drug suppresses the duration of ovulation by around 50%.
Second, Opill thickens cervical mucus which makes it more challenging for sperm to penetrate and reach the egg.
Opill also causes hormonal changes that reduce the chance of pregnancy.
The way that Opill works in the body is similar to other oral contraceptive medications.
A YouTube video from Good Morning America discusses in more detail how oral birth control works and debunks top myths:
