Taking medication, no matter what type, always raises doubts and questions for various reasons. One of the topics that causes the most confusion when it comes to this, is whether an antibiotic cancels out the effect of birth control. Is this true or just a myth? The truth is that yes, there are antibiotics that can cancel out the effect of birth control. But not every type of antibiotic affects the other medication. Also, not every type of birth control will necessarily have its effectiveness compromised. But how can you know how medicines will act in each situation? What should you do when a woman taking birth control pills needs to take antibiotics? How does an antibiotic cancel out the effect of birth control? To understand this, we first need to better understand what each of these two types of medication are.
What is an Antibiotic?
In short, an antibiotic is any kind of medication used to fight another type of organism within a person, especially bacteria1. However, antibiotics have no effect against viruses, requiring a different type of treatment for those cases. Antibiotics basically work by killing the microorganisms that cause infections or by preventing them from multiplying. It’s important to understand how this type of medication works in order to better comprehend how an antibiotic can cancel out the effect of birth control.
What is Birth Control?
The birth control pill is usually a tablet that contains hormones designed to prevent ovulation in a woman’s body, but for this to happen, it must be taken correctly according to the medical prescription. There are several types of pills2, with the most popular being the 21-day type, the 24-day type, and the continuous type. In addition to pills, there are also other contraceptive methods such as the morning-after pill and injectable contraceptives. It’s important to mention all these different types of methods to understand which ones are affected by antibiotics and also how some are impacted.
Which Antibiotic Cancels Out the Effect of Birth Control?
As we emphasized before, specific antibiotics affect the action of birth control methods. And which ones are they? The only antibiotics that, in fact, have this capacity are those used in the treatment of tuberculosis (such as rifampicin and its derivative, rifabutin). Thus, these antibiotics used to treat this disease are well known and proven to cause this type of unwanted effect in women taking birth control pills, as well as in those who have used the morning-after pill or have taken some sort of injectable contraceptive. For this reason, the recommendation is that women who need to take antibiotic medication for tuberculosis treatment should have sexual intercourse only with condoms during the use of these medicines and up to 7 days after taking the last antibiotic. If unprotected intercourse occurred during this period, the chances of pregnancy increase. Of course, there’s no need to panic, but it’s important to pay attention to signs that might indicate pregnancy. Another important point to highlight is that, in any situation—whether or not you are taking medications (antibiotics or others)—if you have had vomiting or diarrhea at least after 4 hours of taking the birth control pill, this can also compromise its effectiveness.
Why Does the Antibiotic Cancel Out the Effect of Birth Control?
In general, this phenomenon happens because the concentration of hormones in a birth control pill is reduced due to the effect this type of antibiotic has in the person’s body. This mainly happens because the intestine is responsible for producing bacteria that generate reactions affecting a woman’s fertility. When these antibiotics are used, the bacteria are also affected, which means these reactions won’t occur, and as a result, the woman becomes fertile during the time the medication is acting in her body.
Other Effects
In addition to questions about antibiotics, some other frequent questions include whether alcohol cancels out the effect of birth control and which medications, besides antibiotics, can also alter the effectiveness of birth control3. Let’s address these two questions separately.
Does Alcohol Cancel Out the Effect of Birth Control?
Consuming alcohol does not cancel out the effect of birth control under any circumstances, even if it is taken together with the pill. But it is important to not overdo alcohol consumption, since both alcohol and the pill are metabolized in the liver, and overloading this organ can cause complications.
Do Medications Cancel Out the Effect of Birth Control?
On the other hand, although they don’t cancel out the effect of birth control like the antibiotics used in tuberculosis treatment, other medications are known to decrease its effectiveness. For example, some antidepressants and anticonvulsants, such as carbamazepine, topiramate, and lamotrigine, as well as some barbiturates, like phenobarbital (which also has anticonvulsant properties) and thiopental (usually indicated for the induction of general anesthesia and also for seizure control), can reduce effectiveness. Likewise, those who manage HIV with Antiretroviral Therapy (ART) may also see a reduction in the effectiveness of their birth control, depending on which antiretrovirals are being used in treatment. For example, patients taking efavirenz, nevirapine, and ritonavir are usually advised to use another barrier contraceptive method, like condoms, because the use of these medications can lower hormone levels in the blood and harm the effect of hormonal contraceptives. On the other hand, it is also often said that some antifungals may cause contraceptives to fail. However, in practice, the medication called griseofulvin has been associated with this effect in various case reports, as an agent that may reduce effectiveness. By better understanding issues such as whether an antibiotic cancels out the effect of birth control or another medication can interfere with its function, we can also understand how this affects our lives and the best way to resolve this sort of problem. Although it is a real concern, there are several ways to protect yourself so that an unintended pregnancy doesn’t occur, and also to avoid any consequences for women who need to use antibiotics that can cancel out the effect of birth control. That’s why it’s important to have this information and to know how to protect yourself when situations like this arise. Also Read: Birth Control Effects – Answers to Common Questions Photo: EME
