Medicines that affect birth control pills: Antibiotics, herbs, and supplements

Which medicines affect birth control?

Different medicines can have an effect on each other when taken at the same time. This is often referred to as drug interactions, and it’s the reason why your doctor asks about what kind of birth control you’re taking and if you’re using any other medications before prescribing a new treatment.

When it comes to birth control, there are a few medicines that can make certain contraceptives less effective by increasing the rate at which the body breaks them down. These medications are called “enzyme-inducing” medicines [1]. Drug interactions with birth control can also go the other way, meaning that the hormones affect how the medicine works. Now, let’s go over a few common medications that are known to interact with hormonal birth control.

Amoxicillin and penicillin: no impact on birth control effectiveness

Most of us have probably been prescribed antibiotics at some point in our lives. Most antibiotics, including two of the most common — amoxicillin and penicillin — can be used alongside hormonal birth control without any issues. Many studies have looked at whether birth control effectiveness is impacted by antibiotics, and the results have been reassuring [2]. 

While most antibiotics themselves won’t lower your birth control’s effectiveness, side effects like nausea or diarrhea might, since they can stop your body from absorbing the hormones needed to prevent pregnancy. Your pill packet should contain instructions for what to do if you vomit or have diarrhea — it usually involves using backup protection (like a condom) during sex. 

Rifamycin antibiotics can impact birth control effectiveness

In fact, only one type of antibiotic has been found to significantly interact with hormonal birth control: rifamycin antibiotics, which are used to treat tuberculosis. Rifamycin is an enzyme-inducing medicine that makes the body break down the hormones in birth control faster [1]. Studies have found that they make certain birth control options, like the combined birth control pill, less effective [3]. 

Anti-fungal medications may interact with birth control

Most anti-fungal medications don’t affect birth control effectiveness. However, there is research suggesting that combined contraceptives (like the pill) can become less effective if used at the same time as an anti-fungal medication called griseofulvin [4]. Your doctor will likely recommend that you use a backup method, for example condoms, during the treatment and for at least a month afterward [4].

Another anti-fungal medicine worth mentioning is fluconazole, which is often prescribed to treat yeast infections. While this medicine doesn’t affect birth control effectiveness, it may lead to higher levels of hormones when taken at the same time as the pill, which could lead to more birth control side effects [5].

Anti-HIV drugs can impact birth control effectiveness

Medications used to treat an HIV infection work by suppressing the levels of the HIV virus in the body [6]. Some anti-HIV drugs are another example of enzyme-inducing medication, which means that they can affect how well certain contraceptives work [1].

A review article from 2012 summarized the findings for different hormonal birth control options, and found that certain anti-HIV drugs can make the pill less effective at preventing pregnancy [7]. However, the results showed that both the birth control shot and hormonal IUD can be used alongside anti-HIV drugs without losing their effectiveness. Other options, like the birth control implant, patch, or ring didn’t have enough studies to determine if they are affected by these types of medications. It’s important that you discuss with your doctor to decide which combo of anti-HIV medications and contraception would suit you best.

Of course, you can also consider using a non-hormonal option, like the copper IUD or condoms, if you don’t want to worry about drug interactions (condoms are also the only method that protects against STIs). Make sure to speak with your doctor to find the best option for you.

Anti-seizure drugs: can impact birth control effectiveness

Anti-seizure drugs fall into two main categories: enzyme-inducing and non-enzyme-inducing [8]. As you may recall from the sections above, enzyme-inducing medications can cause the body to break down hormonal birth control faster than it should, making it less effective at preventing pregnancy. 

Anti-seizure drugs in the enzyme-inducing category can impact the effectiveness of several methods, including the pill, mini pill, implant, patch, and ring. However, the hormonal IUD remains as effective, and you can also consider non-hormonal options like the copper IUD or condoms [8].

It’s also possible for the drug interaction between birth control and anti-seizure drugs to go the other way, meaning that the hormones cause the medication to not work as well [9]. Make sure you discuss your options with your doctor and find a solution that works for you.

Which herbs and supplements affect birth control?

Drug interactions might not be the first thing that comes to mind when you walk up to the supplements shelf in a store — after all, it’s called drug interactions — but it’s actually something worth considering. Supplements aren’t regulated in the same way as medicine, so there’s usually less research into how they may interact with other types of treatments. Nevertheless, supplements can affect how certain medications work, and there are even supplements that you shouldn’t take while you’re on hormonal birth control (and some that are fine). Let’s take a look at some common ones!

Ashwagandha and birth control

Ashwagandha is a medicinal plant that’s been around for thousands of years. Nowadays, ashwagandha supplements are used for a variety of purposes, for example, to help with stress, anxiety, and sleep, and to promote athletic performance. It’s important, though, only to use it as a short-term treatment (for a maximum of three months) since it’s not known if it’s safe to use in the long term [10]. 

While there’s not much research about ashwagandha and birth control specifically, a 2015 study found that ashwagandha doesn’t seem to affect the enzymes that break down hormonal birth control [11], meaning that they can probably be used together. However, ashwagandha can interact with other types of medications (including those that treat high blood pressure, diabetes, and thyroid conditions) [10], so it’s always good to check with your doctor if you’re thinking of giving it a try.

Melatonin and birth control

Melatonin is a hormone involved in our circadian rhythm. The full story of what melatonin does in the body is not entirely understood, and it’s thought to be important for several processes, but one of its main purposes is to help us sleep [12]. Melatonin supplements are most commonly used for sleeping issues. There’s also a significant link between melatonin and the regulation of reproductive hormones during the menstrual cycle [13]. 

There’s no evidence that melatonin has any effect on birth control. However, some research suggests that the hormones in birth control can affect the levels of melatonin that the body produces and therefore increase the risk of experiencing side effects when taking melatonin supplements [14], so you should speak with your doctor if you’re considering taking both at the same time.

Grapefruit and birth control

Did you know that grapefruit can actually affect a number of medications [15]? While research on grapefruit and birth control is limited, one study found that grapefruit can increase how much estrogen the body is able to absorb from birth control [16]. While this most likely doesn’t impact birth control effectiveness, higher estrogen levels in the body may lead to more side effects like breast tenderness, headaches, or nausea [17].

St. John’s wort and birth control

Here’s one you should definitely avoid if you’re on the pill: St John’s wort. This plant-based supplement has a number of uses, including treating mild depression and alleviating symptoms of menopause [18]. 

Similar to the enzyme-inducing medications we covered earlier in this article, St John’s wort can make the body break down the hormones in birth control pills faster than intended and make them less effective [18]. Most studies that have looked into this have been focused on the birth control pill, but it’s good to be cautious even if you’re using other hormonal contraceptives since there isn’t much research about how they may be affected by this supplement. As always, make sure to check with your doctor if you have questions. 

Activated charcoal and birth control

The main use of activated charcoal is as treatment when a person has ingested a toxin, and it works by preventing the body from absorbing it [19]. However, it’s also used in many hair and skincare products, as well as in supplements to help with bloating or indigestion. 

You should be careful if you need to take activated charcoal if you’re on the pill. The charcoal may prevent the body from fully absorbing the hormones in the pill, making this method less effective. One study found that it’s okay if the activated charcoal is taken at least three hours after or twelve hours before you take the pill [20], but it’s best to use a backup method if you need to take activated charcoal while you’re on the pill to be sure.

Magnesium and birth control

There’s no evidence that taking magnesium has any impact on birth control effectiveness. On the contrary, some research suggests that taking birth control pills may result in lower levels of certain minerals — like magnesium — and that it may be beneficial to take magnesium supplements if that’s the case [21]. However, it’s always good to consult with a healthcare provider before deciding to take supplements to check if you need them. A small diet adjustment may work just as well!

Maca root and birth control

Maca root is traditionally used to help promote fertility and increase libido [22]. It hasn’t been studied whether maca root has any impact on hormonal birth control, so you should discuss with your healthcare provider if you’re planning on using both at the same time. 

However, it’s good to know that maca extracts may have estrogen-like properties, so you shouldn’t use these supplements if you have any hormone-sensitive conditions, such as endometriosis, breast cancer, uterine cancer, ovarian cancer, or uterine fibroids [23]. 

Probiotics and birth control

Probiotics can help promote gut health. You can find them in fermented foods (like yogurt or kimchi), as well as in different supplements, and they are generally safe [24]. There aren’t any known effects of probiotics on birth control, but research is lacking in this area so it’s a good idea to check with your doctor if you have questions.

Can birth control lead to vitamin deficiencies?

Now that we’ve covered some common supplements, let’s talk about why you might consider taking supplements in the first place. When you think about birth control side effects, symptoms like mood swings, acne, or low libido might come to mind. But did you know that some birth control options have been linked with lower levels of vitamin B6, B12, and folate (although it’s not fully understood if this is directly caused by the birth control or a result of other factors, such as diet) [25]? These are all part of a group of vitamins that are essential for our metabolism, production of red blood cells, and our brain and nervous system [26]. 

However, research has found evidence that birth control pills can lead to lower levels of vitamin B6 [25]. Similarly, both the pill and the birth control shot have been linked to lower levels of vitamin B12, although, it’s not yet known whether this leads to any symptoms or need for treatment since the levels were still within the range that’s accepted as normal [27].

When it comes to folate (folic acid) and birth control, different studies have found varying results. One study found that folate levels were impacted by older versions of contraceptive pills with higher estrogen contents, but not by modern birth control pills containing less estrogen [25]. However, a review summarizing 17 studies found that folate levels are lower for women using birth control pills [28].

Do you need to take supplements if you’re on birth control?

A balanced diet is, in most cases, enough to cover our nutritional needs. Supplements can be a helpful addition if we’re not getting enough of certain nutrients, minerals, or vitamins, but you don’t have to take any unless there’s a need. It’s also not always the case that more equals better — it’s possible to take too much. Before you start adding supplements to your diet, it’s always best to speak with your doctor who can help you determine if you need any, which ones, and what dosages. 

Here’s a summary of some of the supplements available:

• Vitamin B6: Vitamin B6 is found in several foods, such as red meat, potatoes, beans, and some fruit. A lack of vitamin B6 can result in anemia, a weakened immune system, and depression [26].

• Vitamin B12: Vitamin B12 deficiency can also lead to anemia, as well as fatigue. This vitamin can mostly be found in animal products, and it’s sometimes added to other food items. If you’re vegan, it’s generally recommended to consider taking supplements since it can be difficult to get enough vitamin B12 from a vegan diet [26].

• Folate (folic acid): Folate is found naturally in a number of foods, for example, leafy vegetables, grains, nuts, meat, and dairy. Low folate levels during pregnancy are related to a higher risk of birth defects, preterm labor, and lower birth weight [26]. So if you’re planning on getting pregnant in the near future (even if you’re on birth control now), it’s a good idea to speak with your healthcare provider to see if they recommend you take folate supplements.

• Magnesium: One study found that birth control may lead to lower levels of minerals like magnesium [21], and symptoms of magnesium deficiency include fatigue and muscle cramps [29]. Magnesium is found naturally in foods like leafy greens, seeds, grains, and dark chocolate.

• Zinc: Another mineral that may be lower for women on the pill [21], zinc is needed for our immune system and metabolism [30]. You can find zinc naturally in seeds, legumes, grains, eggs, and poultry.

Are there any vitamins you shouldn’t take while on birth control?

There isn’t any evidence that vitamins would make birth control less effective, so there’s no need to avoid any specific vitamins. However, as with any supplements, you also don’t need to take additional vitamins unless you have a vitamin deficiency.

Interestingly, there is evidence suggesting that higher estrogen levels may be linked to higher levels of vitamin D. Studies have found that women taking birth control that contains estrogen tend to have higher vitamin D levels than those who don’t, and the effect of vitamin D supplements is improved for those on birth control [31].

Additionally, taking vitamin C together with birth control containing estrogen may increase your estrogen levels, which can lead to more side effects from the birth control itself for some people [32].

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