Lamotrigine (Lamictal) Dosages for Adults: Your GoodRx Guide

Lamotrigine (Lamictal, Subvenite) is one of several seizure medications that treats seizures. It’s also useful for managing symptoms of bipolar 1 disorder. If you’re starting treatment, you’ll need to follow a specific dosing schedule during the first several weeks.

So, what’s a typical lamotrigine dosage, and how is your dose usually determined? We answer those questions and more below. Keep in mind that your lamotrigine may be different from what’s discussed below, as determined by your healthcare provider.

Lamotrigine dosage forms

Lamotrigine comes in different formulations, including an immediate-release (IR) oral tablet. But if you have difficulty swallowing pills, the lamotrigine tablet for oral suspension can be chewed or dissolved in water or diluted fruit juice. Another option is the orally disintegrating tablet (ODT), which you dissolve in your mouth.

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For adults, the IR tablet, ODT, and tablet for oral suspension are approved for maintenance treatment of bipolar 1 disorder and different types of seizures, including:

• Partial-onset seizures

• Primary generalized tonic-clonic seizures 

• Generalized seizures of Lennox-Gastaut syndrome

Lamotrigine is also available as an extended-release (ER) tablet. It’s approved for generalized tonic-clonic seizures and partial-onset seizures. The ER tablet cannot be chewed, cut, or crushed. Doing so could affect how the medication is released in the body.

What’s the typical lamotrigine dosage for adults?

The typical lamotrigine dosage depends on what you’re treating. It also depends on whether you take other medications that interact with lamotrigine.

Since lamotrigine can cause a severe rash, you’ll typically start with a lower dosage that’s slowly increased (titrated) over several weeks. Your dosage may be adjusted based on how you respond to treatment.

Good to know: Lamotrigine comes in “starter kits” that can help make it easier to stick to your specific dosing schedule. These kits provide the exact quantity of tablets you’ll need for the first 5 weeks of treatment.

Seizures

For seizures, lamotrigine may be taken along with other seizure medications. In certain situations, you may transition from a different medication to taking lamotrigine by itself.

Below is a typical lamotrigine dosing schedule when it’s tajken along with other seizure medications. Keep in mind that your dosing schedule may look different if you’re taking certain interacting medications (which we’ll discuss later).

Similarly, a typical lamotrigine ER dosing schedule when taken along with other seizure medications may look like this:

When taken alone, the typical lamotrigine dosage for seizures is: 

• Lamotrigine IR, ODT, and tablets for oral suspension: 500 mg daily, given as two divided doses

• Lamotrigine XR: 250 mg to 300 mg given once daily

Keep in mind that if you’re transitioning from another seizure medication to lamotrigine, your lamotrigine dosing schedule will depend on the other medication you’re taking.

Bipolar disorder

Lamotrigine IR, ODT, and tablets for oral suspension are approved for maintenance treatment of bipolar 1 disorder. You may be prescribed lamotrigine on its own or in combination with other medications.

The typical lamotrigine dosing schedule for bipolar disorder is below. But similar to seizures, your lamotrigine dosage may be higher or lower depending on what other medications you’re taking.

Are there any dosage adjustments for medical conditions or interactions?

Certain medical conditions and drug interactions affect how lamotrigine is cleared from the body. In this case, you may need a different lamotrigine dosage.

Kidney or liver problems

Your kidneys help remove lamotrigine from the body. Depending on how well your kidneys are working, your healthcare provider may prescribe a lower lamotrigine dose. Your dosage may also be lower if you have moderate or severe liver problems.

Drug interactions

Lamotrigine has many drug interactions. Dosage adjustments may be needed if you start or stop taking an interacting medication. The following seizure medications interact with lamotrigine and require unique dosing schedules:

• Carbamazepine (Tegretol)

• Phenytoin (Dilantin, Phenytek)

• Phenobarbital

• Primidone (Mysoline)

• Valproate products, such as Depakote and Depakene

If you’re taking carbamazepine, phenytoin, phenobarbital, or primidone, your lamotrigine dosage may be higher, especially to start. If you’re taking valproate, your lamotrigine dosage may be lower.

This isn’t a comprehensive breakdown of all lamotrigine interactions and dosage adjustments. Make sure your healthcare team has your current medication list to check for interactions ahead of time.

What happens if you miss a dose of lamotrigine?

Taking lamotrigine every day as directed is the best way to avoid seizures and manage symptoms of bipolar disorder.

If you miss a lamotrigine dose, just take it as soon as you remember. But if it’s close to when you would normally take your next dose, skip the dose you missed and take your next dose on schedule. Don’t double up on doses to make up for your missed dose.

If you’re not sure what to do, contact your healthcare provider or pharmacist. And if you’re forgetting to take lamotrigine often, they can provide tips for remembering to take it. This may include setting reminders on your phone or using a medication reminder app.

Keep in mind: If you’ve missed more than one lamotrigine dose, contact your healthcare provider. It’s possible that you may need to restart the dose titration schedule to minimize the risk of a severe rash.

What should you do if you take too much lamotrigine?

Taking too much lamotrigine can cause coordination problems and uncontrolled eye movements. It can also increase the risk of a severe rash. Other serious side effects, such as loss of consciousness, seizures, and heart problems, are possible. In severe cases, coma or even death have been reported. 

If you think that you or your child has taken too much lamotrigine, contact your healthcare provider immediately. You can also call Poison Control at 1-800-222-1222 for guidance. If you experience any symptoms that feel severe or life-threatening, have someone take you to the nearest emergency room. 

How to save on lamotrigine

There are ways to save on lamotrigine, which is available as lower-cost generics. With GoodRx, you could save over 60% off the average retail price of lamotrigine at certain pharmacies. Below are examples of prices with a GoodRx discount:

• Lamotrigine IR tablets: $9.00

• Lamotrigine ODTs: $42.08

• Lamotrigine tablets for oral suspension: $10.80

• Lamotrigine ER tablets: $22.00

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Written by:

Sandy P. Bonfin, PharmD, BCPS

Sandy Bonfin has 9 years of experience as a pharmacist and has been working as a clinical pharmacist in a hospital in Florida for the past 7 years after a short stint as a mail-order retail pharmacist. Sandy has worked in pediatric medicine, emergency medicine, internal medicine, and intensive care.

Edited 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.

Reviewed by:

Amy B. Gragnolati, PharmD, BCPS

Amy Gragnolati, PharmD, BCPS, is a pharmacy editor for GoodRx. Amy currently holds her pharmacist license in Georgia and California.

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