Anticonvulsant-Birth Control Interaction Calculator
This tool helps you determine if your seizure medication affects your birth control method. Select your anticonvulsant and birth control method below.
Many women taking anticonvulsants for epilepsy or other seizure disorders don’t realize their birth control might not be working as expected. This isn’t a rare issue-it’s a well-documented, clinically significant interaction that puts thousands of women at risk for unintended pregnancy every year. If you’re on medications like carbamazepine, oxcarbazepine, or topiramate, and you’re using the pill, patch, or ring, your contraception could be failing without you knowing it.
How Anticonvulsants Break Down Birth Control
The problem starts in your liver. Certain anticonvulsants trigger enzymes called cytochrome P450, which speed up how fast your body breaks down hormones. Oral contraceptives rely on steady levels of estrogen and progestin to prevent ovulation. When these hormones are metabolized too quickly, they never reach the concentration needed to work. Studies show that enzyme-inducing anticonvulsants can drop estrogen levels by 15% to 60% and progestin by 20% to 50%. That’s not a small drop-it’s enough to let ovulation happen. For example, women taking topiramate at 400 mg per day saw estrogen levels fall by 43%. At that point, the pill becomes unreliable, even if taken perfectly.Which Anticonvulsants Are the Worst Offenders?
Not all seizure medications affect birth control the same way. Some are high-risk. Others are safe. Here’s the breakdown:- High risk (strong enzyme inducers): Carbamazepine (Tegretol), oxcarbazepine (Trileptal), phenytoin (Dilantin), phenobarbital, primidone (Mysoline), felbamate (Felbatol), and topiramate (Topamax) at doses over 200 mg/day.
- Unique interaction: Lamotrigine (Lamictal) doesn’t speed up hormone breakdown-but birth control pills cut lamotrigine levels by half. That increases seizure risk. Plus, when you stop taking the pill during your placebo week, lamotrigine spikes, which can cause dizziness, blurred vision, or even seizures.
- Safe options: Valproate (Depakote), gabapentin (Neurontin), pregabalin (Lyrica), and levetiracetam (Keppra) don’t interfere with hormonal birth control.
The FDA requires drug labels to warn about these interactions. The Tegretol package insert says plainly: “Contraceptives containing estrogen or progestin may be ineffective when used concurrently with Tegretol.” If your doctor didn’t mention this, they’re not up to date.
What Birth Control Methods Still Work?
If you’re on a high-risk anticonvulsant, your options aren’t gone-they just need to change. Here’s what works:- Levonorgestrel IUDs (Mirena, Kyleena): These release progestin directly into the uterus. Blood levels stay high enough to prevent pregnancy even with enzyme inducers. Pregnancy rates are under 0.1% per year.
- Copper IUD (ParaGard): No hormones at all. Works by creating an inflammatory reaction that stops sperm. Completely unaffected by any medication.
- Depo-Provera (DMPA): The shot delivers 150 mg of progestin every 12-13 weeks. That’s such a high dose that liver metabolism can’t break it down fast enough to cause failure.
- Progestin-only pill (minipill): May work if taken perfectly every day, but it’s not ideal. Missing a pill by even 3 hours can reduce effectiveness. Most experts don’t recommend it as a first choice here.
What doesn’t work? The pill, patch, and ring. Even if you take them perfectly, the drugs are still breaking down the hormones too fast. Emergency contraception is also risky. Plan B (levonorgestrel) loses about half its effectiveness. Ella (ulipristal acetate) may not work at all. If you need emergency contraception, go straight to a copper IUD inserted within 5 days-it’s the only reliable option.
What About Lamotrigine and Birth Control?
This is a tricky one. Lamotrigine is often the go-to drug for women with epilepsy because it has fewer side effects and less risk to a developing baby. But it’s caught in the middle. Combined hormonal birth control cuts lamotrigine levels by about 50%. That means your seizure control could slip. One woman on Reddit shared: “I had two seizures in a week after starting the pill. My neurologist didn’t know the pill would lower my lamotrigine.” The fix? Either avoid estrogen entirely and use a progestin-only method, or adjust your lamotrigine dose. Most doctors increase the dose by 50-100% when someone starts hormonal birth control. But you need close monitoring-blood tests every few weeks-to make sure you’re in the safe range. Avoid the placebo week in your pill pack. Extended-cycle pills (taking active pills for 84 days straight) help keep lamotrigine levels stable.Why This Isn’t Just About Pregnancy
Unplanned pregnancy is dangerous for women on anticonvulsants. Many seizure medications-especially enzyme inducers-carry a 30-40% higher risk of major birth defects compared to the general population’s 2-3%. That includes heart defects, cleft palate, and neural tube defects. Plus, pregnancy can make seizures worse. Hormonal shifts, sleep disruption, and stress all trigger seizures. If you’re not planning to get pregnant, you’re not just protecting yourself-you’re protecting a future child.
Why So Many Women Don’t Know This
A 2022 survey by the Epilepsy Foundation found that only 35% of women with epilepsy got counseling about birth control interactions from their neurologist. Only 22% heard it from their gynecologist. That’s a massive gap. One woman wrote in a support group: “I got pregnant on Ortho Tri-Cyclen while taking Tegretol. My neurologist never mentioned it. My OB said the pill was fine. No one connected the dots.” This isn’t just a lack of communication-it’s a systemic failure. Neurologists focus on seizure control. Gynecologists focus on contraception. Neither always checks what the other is prescribing.What You Should Do Right Now
If you’re on an anticonvulsant and using hormonal birth control, here’s your action plan:- Identify your medication. Is it carbamazepine, topiramate, phenytoin, or lamotrigine? If yes, you’re at risk.
- Check your current method. Are you using the pill, patch, or ring? If yes, stop relying on it.
- See both your neurologist and gynecologist. Bring this article. Ask: “Does my medication interfere with my birth control? What’s the safest option for me?”
- Choose a non-interfering method. Go for a levonorgestrel IUD or copper IUD. They’re long-lasting, over 99% effective, and require no daily effort.
- Use backup protection. If you’re still on a risky method, use condoms every time until you switch.
Don’t wait for your next appointment. If you’re sexually active and on one of these drugs, your birth control might already be failing. You don’t need to guess. You don’t need to hope. You just need to act.
What’s Changing in 2025?
Newer anticonvulsants like perampanel (Fycompa) and brivaracetam (Briviact) don’t induce liver enzymes. That means they’re safer for women who need reliable contraception. More doctors are switching patients to these drugs when possible. The NIH is tracking 5,000 pregnancies to better understand how different anticonvulsants affect birth outcomes. And the Bill & Melinda Gates Foundation is funding a non-hormonal contraceptive gel that works without touching liver metabolism-potentially solving this problem for good. In early 2024, the American College of Obstetricians and Gynecologists and the American Academy of Neurology are launching a shared decision-making toolkit for doctors. It’s designed to make sure no woman slips through the cracks again.For now, the solution is simple: Know your drugs. Know your options. Don’t assume your birth control is working. And don’t let silence put your health at risk.
December 23, 2025 AT 09:32
Charles Barry
Let me guess-your doctor is part of the pharmaceutical cabal. They don’t want you to know that Big Pharma designed these drugs to keep women dependent on both seizure meds AND birth control. Why? Because if you got a copper IUD, they’d lose billions. The FDA? Controlled by the same people who invented the pill. You think they care about your fertility? They care about your monthly co-pay. Topiramate? It’s not just breaking down hormones-it’s breaking down your autonomy. Wake up. The system is rigged.
And don’t even get me started on the ‘shared decision-making toolkit’-that’s just corporate speak for ‘we’ll pretend we care while you keep paying for unnecessary blood tests.’
December 24, 2025 AT 09:15
Rosemary O'Shea
Oh, darling, how quaint. You’ve clearly never read a proper pharmacokinetics textbook. The real tragedy here isn’t the interaction-it’s the fact that most women still think a ‘pill’ is a legitimate form of contraception. If you’re on enzyme inducers and relying on anything less than a levonorgestrel IUD, you’re not just irresponsible-you’re culturally negligent. I’ve seen women in London lose three pregnancies before they even realized their carbamazepine was sabotaging their estrogen. And now you’re surprised? The science has been clear since 2008. This isn’t a gap in communication-it’s a failure of intellectual discipline.
Also, ‘emergency contraception’? Please. If you’re having unprotected sex and aren’t on a copper IUD, you’re not ‘at risk’-you’re just statistically inevitable.
December 25, 2025 AT 20:46
Tony Du bled
Wow. I didn’t realize my lamotrigine and the pill were playing tug-of-war with my brain. I had two seizures last month and thought it was just stress. Turns out my OB prescribed me the pill without checking with my neurologist. Guess who’s getting an IUD next week. Thanks for the wake-up call. No drama, no conspiracy-just bad coordination between doctors. I’m not mad, just relieved I found this before it got worse.
December 27, 2025 AT 12:59
Jamison Kissh
It’s fascinating how medicine treats women’s bodies as a series of isolated systems. Neurology focuses on seizure thresholds, gynecology on hormonal regulation-but no one looks at the whole organism. We’ve reduced women’s health to algorithmic interactions: drug A × drug B = risk C. But what about the lived experience? The woman who misses her pill because she had a seizure at 3 a.m.? The one who can’t afford an IUD? The one whose doctor dismisses her concerns because ‘the pill is fine’?
This isn’t just a pharmacological problem. It’s a philosophical one. We’ve built a system that optimizes for efficiency, not humanity. And until we fix that, no amount of toolkit launches or NIH studies will matter.
December 28, 2025 AT 05:55
Candy Cotton
It is imperative to note that the United States Department of Health and Human Services issued a formal advisory in 2021 regarding the concomitant use of enzyme-inducing antiepileptic drugs and hormonal contraceptives. The American College of Obstetricians and Gynecologists has reiterated this guidance in their Practice Bulletin No. 224. Any failure to adhere to these evidence-based standards constitutes a deviation from the standard of care. Women who experience unintended pregnancy under these circumstances may have legal recourse if their providers failed to document counseling. This is not a suggestion. It is a clinical obligation. Compliance is non-negotiable.
December 29, 2025 AT 13:41
Jeremy Hendriks
There’s a deeper truth here: we live in a world where women are expected to manage their biology like a corporate budget-balance hormones, suppress ovulation, avoid side effects, all while the system ignores the fact that their bodies aren’t machines.
They give you a pill and say ‘take it daily.’ But what if your brain is busy trying not to seize? What if you’re too exhausted to remember? What if your doctor doesn’t know? The real failure isn’t the drug interaction-it’s the assumption that women can, and should, be perfect managers of their own physiology. We built a system that demands perfection from people who are already fighting for survival. And then we blame them when they fail.
Maybe the real solution isn’t a better IUD. Maybe it’s a society that doesn’t treat women’s bodies like collateral damage in a medical spreadsheet.
December 30, 2025 AT 05:25
Tarun Sharma
Thank you for this detailed and clinically accurate overview. In India, access to specialized neurology and gynecology care remains limited. Many women are unaware of these interactions. This information should be translated into regional languages and disseminated through primary health centers. A simple pamphlet could save lives.
December 30, 2025 AT 18:04
Kiranjit Kaur
Thank you for sharing this 💖 I’ve been on lamotrigine for 8 years and just started the pill last year-no idea it could affect my seizure control. I’m going to see my neurologist this week and ask about switching to a non-hormonal option. I feel so much less alone knowing others have been through this. Let’s keep talking about this-no woman should have to figure this out on her own 🌸