9 Lacosamide (Vimpat) Side Effects to Know About

Lacosamide (Vimpat) is a medication that treats certain types of seizures in adults and children. You can take lacosamide on its own, but it’s often combined with other anti-seizure medications.

If lacosamide is prescribed for you or your child, you’re likely wondering what to expect while taking it. Let’s review nine possible Vimpat side effects to be aware of.      

1. Dizziness

The most common lacosamide side effect in clinical studies was dizziness. It can be severe enough to cause trouble with balance and movement for some people. Dizziness is more likely when you first start taking lacosamide or if you’re taking more than 400 mg per day.

If you’re starting to feel dizzy, it may help to move slowly and use a wall or furniture for support. This can help you avoid falls. It may also be a good idea to avoid driving until you’re sure you can do so safely.

It’s likely that dizziness will go away once your body adjusts to taking lacosamide. But if it doesn’t go away or worsens, let your healthcare provider know. They may need to change your dose or make sure there’s not something else going on.

2. Headache

Headache is another common Vimpat side effect. Like dizziness, it’s likely to go away as your body gets used to taking lacosamide. But if it doesn’t improve, be sure to let your provider know.

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In the meantime, an over-the-counter pain reliever such as acetaminophen (Tylenol) or ibuprofen (Advil, Motrin) may be helpful. But these pain relievers aren’t safe for everyone, so make sure you clear it with your provider first.

3. Vision changes

Lacosamide can affect your eyes in several ways. You may experience double vision, blurred vision, or abnormal eye movements (nystagmus). In clinical trials, these effects were more common with higher doses of Vimpat (400 mg per day or more).

If you’re experiencing any changes to your vision, move slowly and carefully to avoid falls. You may also want to avoid driving until you’re able to see clearly. 

Let your healthcare provider know about any changes to your vision. They may want to wait and see if the symptoms resolve on their own. Or they may want to make a change to your medication.

4. Nausea

Nausea is another possible side effect of lacosamide. Dizziness and double vision can make nausea more likely. But it can also happen on its own. Like other side effects, nausea was reported more often with higher doses of lacosamide.

You can take Vimpat with or without food. But if an upset stomach is an issue, try taking Vimpat with a meal or snack to help manage nausea. It’s likely to go away over time, but if it doesn’t, be sure to let your healthcare provider know.

5. Fatigue

You may also feel exhausted or sleepy while taking Vimpat. Higher doses are more likely to cause this side effect. But fatigue does seem to go away over time for most people.

It may help to exercise — even a walk around the block can give you an energy boost. Short naps during the day are also an option.

If fatigue is stopping you from participating in normal activities, or if you’re also feeling depressed, talk to your healthcare provider. Sometimes fatigue may be a sign of more serious mental health changes caused by lacosamide. Other times it can be managed with time or a change in your dose. Your provider can help determine the best course of action.

6. Tremor

Tremors are another possible lacosamide side effect. This isn’t as common, but it’s possible — especially at medium-to-high doses.

Tremors usually aren’t anything to worry about. But it’s still a good idea to let your provider know if you notice shaky hands after starting Vimpat. They’ll want to make sure they’re caused by your medication and not something else.

7. Heart rhythm changes

Lacosamide can sometimes cause changes to your heart rhythm. This isn’t a common issue, but may include a slow or irregular heartbeat. These changes can be serious and lead to heart attack or even death if not treated.

You may be at a higher risk for heart rhythm changes if you:

• Have a history of heart arrhythmias (irregular heartbeat)

• Have a history of heart disease (such as heart failure or heart attack)

• Take other medications that affect your heartbeat (such as beta blockers and calcium channel blockers) 

• Have other forms of heart disease

Atrial fibrillation and atrial flutter are specific types of arrhythmias that may occur with lacosamide. They’re rare side effects, and seem to be more common in people with diabetic neuropathy (nerve pain) or heart disease.

If you have a history of heart problems or diabetic neuropathy, talk to your healthcare provider about the pros and cons of lacosamide treatment. If you’re taking lacosamide and notice a change in your heartbeat along with chest pain, trouble breathing, or feeling faint, seek medical care right away. 

8. Severe allergic reaction

In very rare cases, lacosamide may cause a severe allergic reaction known as DRESS. This stands for “drug reaction with eosinophilia and systemic symptoms.” It can happen 2 to 8 weeks after starting lacosamide. DRESS can cause a fever, rash, and swelling of the face and lymph nodes. Liver, kidney, and heart damage are also possible.

DRESS can be life-threatening without proper treatment. But lacosamide may be less likely to cause it than other anti-seizure medications. Still, if you notice any of the above symptoms while taking lacosamide, seek medical care right away.

9. Suicidal thoughts

Anti-seizure medications are associated with an increased risk of suicidal thoughts and behavior in people who take them. It’s unclear if newer seizure medications, such as Vimpat, raise the risk of suicide as much as older medications. But it’s still good to be aware of. These thoughts and behaviors can appear as early as 1 week into treatment, but could happen at any time while you’re taking lacosamide.

If you notice negative changes in your mood or thoughts while taking lacosamide, reach out to your healthcare provider. If you’re having thoughts of suicide, you’re not alone, and help is available. Call the National Suicide Prevention Lifeline at 988, or text HOME to 741-741 to reach the Crisis Text Line.

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Written by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

Reviewed by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

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