Immediate Action Required: Evaluate for Drug Interaction and Neurological Emergency
You must immediately discontinue or adjust these medications under medical supervision, as "blanking out" episodes while taking lamotrigine and fluvoxamine together represent a potentially serious drug interaction that can cause toxic lamotrigine levels, seizure breakthrough, or other neurological complications. 1
Understanding the Critical Drug Interaction
Fluvoxamine significantly inhibits the metabolism of multiple medications through cytochrome P450 enzyme effects, creating substantial risk for drug-drug interactions. 2 While the evidence base specifically addresses lamotrigine's interaction with combined oral contraceptives rather than fluvoxamine directly, the mechanism of concern is similar—alterations in lamotrigine metabolism can lead to:
- Decreased lamotrigine levels (increasing seizure risk if used for epilepsy) 1
- Increased lamotrigine levels (causing toxicity symptoms)
- Fluctuating levels (causing intermittent neurological symptoms like "blanking out")
What "Blanking Out" Could Represent
Your symptoms require urgent evaluation for:
- Absence seizures or seizure breakthrough if lamotrigine levels have dropped 1, 3
- Lamotrigine toxicity including confusion, ataxia, or altered consciousness if levels are elevated 4
- Serotonin syndrome from the combination, though less likely to present as isolated "blanking out" 5, 2
- Psychiatric side effects including dissociative symptoms, as lamotrigine can induce acute psychotic episodes and hallucinations 4
Immediate Steps to Take
Contact your prescribing physician within 24 hours to report these episodes. Do not stop medications abruptly without medical guidance, as sudden lamotrigine discontinuation can trigger seizures. 1
Your physician should:
- Obtain serum lamotrigine levels immediately to assess for toxicity or subtherapeutic dosing 1
- Perform neurological examination including assessment for ataxia, diplopia, or other signs of lamotrigine toxicity 4
- Review the timing of when fluvoxamine was added relative to when symptoms began
- Consider EEG monitoring if seizure activity is suspected 4
Medication Management Options
The safest approach is to avoid combining multiple medications with significant interaction potential. 2 Your physician will likely consider:
- Switching from fluvoxamine to an alternative SSRI with lower drug interaction potential (sertraline, citalopram, or escitalopram have fewer cytochrome P450 effects) 2
- Adjusting lamotrigine dosing based on serum levels and clinical response 1
- Monitoring closely in the first 24-48 hours after any medication or dose changes 5, 2
Critical Safety Monitoring
If you experience any of the following, seek emergency care immediately:
- Loss of consciousness or prolonged unresponsiveness
- Seizure activity
- Severe confusion or disorientation
- Visual disturbances or double vision
- Difficulty walking or severe dizziness
- Muscle rigidity, high fever, or rapid heart rate (signs of serotonin syndrome) 5, 2
Common Pitfall to Avoid
Do not assume these episodes will resolve on their own or represent "adjustment" to the medications. 4 Lamotrigine can cause serious psychiatric and neurological symptoms that require active intervention, and the combination with fluvoxamine creates unpredictable pharmacokinetic effects. 2, 6