Ingrezza and Tremors: Effect Profile
Ingrezza (valbenazine) can worsen tremors as a side effect by causing drug-induced parkinsonism, which includes tremor as a cardinal feature, and this occurs in approximately 3-5% of patients treated for tardive dyskinesia. 1
Understanding the Mechanism and Risk
Ingrezza is a VMAT2 inhibitor that works by reducing dopaminergic transmission, which is the same mechanism that can precipitate parkinsonian symptoms including tremor 1
The FDA label explicitly warns that "INGREZZA and INGREZZA SPRINKLE may cause parkinsonism" with specific mention of "shaking (tremors)" as one of the Parkinson-like symptoms to monitor 1
In controlled trials for tardive dyskinesia, parkinson-like adverse events occurred in 3% of Ingrezza-treated patients versus <1% of placebo patients 1
Postmarketing reports have documented severe parkinsonism in patients taking Ingrezza, with most cases occurring within the first two weeks after starting or increasing the dose 1
Clinical Distinction: Tardive Dyskinesia vs. Tremor
Ingrezza is FDA-approved specifically for tardive dyskinesia, which characteristically involves choreiform and athetoid movements—NOT tremor 2, 3
Classic tardive dyskinesia presents with rapid involuntary facial movements and extremity movements, but tremor is not a primary feature of TD 3
If a patient on antipsychotics develops tremor, this more likely represents drug-induced parkinsonism rather than tardive dyskinesia, especially if occurring early in treatment 3
Management Recommendations
Reduce the dose or discontinue Ingrezza if clinically significant parkinson-like signs or symptoms (including tremors) develop 1
The FDA label emphasizes that drug-induced parkinsonism "has the potential to cause more functional disability than untreated chorea" in some patients 1
Associated symptoms with Ingrezza-induced parkinsonism include falls, gait disturbances, tremor, drooling, and hypokinesia 1
In cases where follow-up was available, parkinson-like symptoms resolved following discontinuation of Ingrezza therapy 1
Important Caveats
Do NOT use anticholinergics (like benztropine) to treat tremor if it's part of tardive dyskinesia, as anticholinergics can worsen TD 2
However, if the tremor represents drug-induced parkinsonism (not TD), anticholinergic agents may be beneficial 3
The critical clinical decision is distinguishing between drug-induced parkinsonism (where tremor is expected and anticholinergics may help) versus tardive dyskinesia (where tremor is atypical and anticholinergics worsen the condition) 2, 3
Bottom Line for Clinical Practice
Ingrezza does not help tremors—it can cause or worsen them through drug-induced parkinsonism. The medication is designed to treat the choreiform movements of tardive dyskinesia, not tremor disorders. If tremor develops or worsens on Ingrezza, dose reduction or discontinuation should be strongly considered rather than adding additional medications. 1