More evidence of troublesome side-effects related to SSRI's / SNRI's ... indicates that this happens when the drug is started, or doses are increased.
Note: "Extrapyramidal reactions" is a fancy term for a range of involuntary movements ... from the wiki article on this topic [https://en.wikipedia...idal_symptoms]:
Extrapyramidal symptoms (EPS), also known as extrapyramidal side effects (EPSE), are drug induced movement disorders that include acute and tardive symptoms. These symptoms include dystonia (continuous spasms and muscle contractions), akathisia (motor restlessness), parkinsonism (characteristic symptoms such as rigidity, bradykinesia, and tremor), and tardive dyskinesia (irregular, jerky movements).
Extrapyramidal Reactions Associated With Serotonergic Antidepressants: A Follow-up Literature Review [abstract only]
Annals of Pharacotherapy, 2015
From the Abstract:
Objective: Extrapyramidal reactions (EPRs) [movement disorders] associated with serotonergic antidepressant treatments have been reported since 1958. These reactions can be distressing for patients and complicate treatment.
Our objective was to complete a follow-up review of published EPR cases reported for serotonergic antidepressants.
Data Sources: Published cases between January 1998 and May 2015 were collected through a medical literature search. Citation reference lists were also searched manually.
Study Selection and Data Extraction: Identified cases were reviewed for patient age, gender, psychiatric diagnosis, dosage, time to reaction onset, concurrent medications, and EPR description. Cases were excluded when there was not a clear description, if descriptions were not consistent with accepted deﬁnitions, or if the written English was poor.
We included cases of akathisia, dystonia, dyskinesia, parkinsonism, or mixed EPRs. Authors scored each case using the Naranjo adverse drug reaction probability scale.
Data Synthesis: We identified 86 published reports involving 91 patients; selective serotonin reuptake inhibitors were implicated in 80.2% of cases. All EPR types were reported: 17 akathisia cases, 18 dyskinesia cases, 27 dystonia cases, 19 parkinsonism cases, and 10 mixed EPR cases.
EPRs typically occurred within 30 days of either treatment initiation or dose increase. Age, gender, antidepressant dosing, or concurrent antipsychotic treatment did not appear to broadly contribute to EPR risk. Naranjo scores ranged from 2 to 8.
Conclusions: Case reports associating serotonergic antidepressants with EPRs continue to be published.
Practitioners are advised that monitoring for such is important. Rigorous research efforts are needed to better understand the clinical risk factors for these adverse drug reactions.