5 Lamotrigine Interactions to Know About

Lamotrigine (Lamictal) is an antiepileptic medication. It’s FDA approved to treat certain seizure conditions. It’s also approved to treat bipolar 1 disorder.

Lamotrigine has many interactions. Many of them can change how lamotrigine is cleared from the body. This can make it less effective, or make side effects worse.

Here, we’ll discuss five important lamotrigine interactions. But this isn’t a complete list. It’s best to talk to your healthcare provider and pharmacist about all of the medications you’re taking. They can help you more thoroughly check for lamotrigine interactions.

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1. Divalproex and valproic acid

Divalproex (Depakote) and valproic acid — collectively called valproate — are two other anti-seizure medications. Divalproex can also help treat bipolar disorder and prevent migraines. Valproate products and lamotrigine are often prescribed together for seizures or bipolar disorder. But it’s important to know that they do interact.

Valproate products can significantly raise blood levels of lamotrigine. This interaction can worsen lamotrigine side effects, such as dizziness. It can also raise the risk of developing rare but severe skin reactions, like Stevens-Johnson syndrome, while taking lamotrigine.

To manage this interaction, your healthcare provider will likely prescribe a lower lamotrigine dose when starting the combination. They may also lower your existing dose, if a valproate product is being added to your treatment regimen.

2. Other antiepileptic medications

There are other antiepileptics that interact with lamotrigine, such as:

• Carbamazepine (Tegretol)

• Phenytoin (Dilantin)

• Phenobarbital

Similar to valproate, these medications can be combined with lamotrigine. But certain dose changes may be needed to avoid problems.

These three anti-seizure medications can lower lamotrigine levels in the body. So lamotrigine may be less effective. This could mean a higher risk of seizures or a worsening of bipolar disorder symptoms. Healthcare providers typically raise lamotrigine doses when combining it with these other medications.

3. Certain hormonal birth control

Ethinyl estradiol, the most common estrogen in hormonal birth control, can interact with lamotrigine. This particular estrogen can lower lamotrigine levels by about 50% to 60%. Lower levels can lower lamotrigine’s effectiveness.

What’s more, many birth control pills have changing levels of estrogen throughout each pack. If estrogen levels go up, lamotrigine levels can drop. If estrogen levels fall, lamotrigine levels increase. Changing estrogen levels can make it hard to get consistent results with lamotrigine.

And if you have a pill-, patch-, or ring-free week, your lamotrigine levels can rapidly rise. This can raise your risk of side effects during your off-week.

Discuss birth control options with your healthcare provider. There are contraceptives that use different types of estrogen. There’s also estrogen-free and hormone-free birth control methods.

4. Rifampin

Rifampin (Rifadin) is a type of antibiotic. It can be prescribed to treat tuberculosis and prevent meningitis. Rifampin can significantly lower lamotrigine levels in the blood. This can make lamotrigine less effective, especially if you’ll be taking rifampin for a while.

Some rifampin treatments are only a few days long. In these cases, your lamotrigine dose will likely be kept the same.

Other rifampin regimens may be prescribed for several months or longer. In these instances, a healthcare provider may raise the lamotrigine dose until you finish rifampin.

5. Certain HIV medications

Certain HIV medications can lower lamotrigine blood levels. These medications include Kaletra (lopinavir/ritonavir), as well as a combination of atazanavir (Reyataz) and ritonavir (Norvir). These HIV medications can make lamotrigine less effective. A healthcare provider would likely raise the dose of lamotrigine in this case.

When should I contact my healthcare provider about a lamotrigine interaction?

Contact your healthcare provider or pharmacist if you have symptoms of a lamotrigine interaction. These could include new or worse lamotrigine side effects like dizziness, balancing problems, or double vision. Interaction symptoms could also include a return or increase of your health condition symptoms.

The best way to manage lamotrigine interactions is to prevent them upfront. Share a current medication list with your healthcare provider and pharmacist. Include medications that are prescription, over the counter, and herbal supplements. Be sure to share your list any time you start, stop, or change medications. This can help your healthcare team limit or avoid complications from interactions.

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Written by:

Victoria Dadebo, PharmD, BCPS

Victoria Dadebo is a freelance pharmacy writer who began contributing to GoodRx in 2022. She has experience in both community and hospital settings, and she is furthering her pharmacy training to specialize in mental health.

Edited by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

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