Can Lexapro Cause Pupil Dilation?
Yes, Lexapro (escitalopram) can cause mild pupillary dilation, and this side effect is specifically warned about in the FDA drug label. 1
Mechanism and Clinical Significance
The FDA-approved labeling for escitalopram explicitly states that taking the medication "can cause mild pupillary dilation, which in susceptible individuals, can lead to an episode of angle closure glaucoma." 1 This is a recognized anticholinergic-type effect, though escitalopram is primarily a selective serotonin reuptake inhibitor (SSRI). 1
Key Clinical Points:
Pupil dilation from escitalopram is typically mild and occurs as part of the drug's systemic effects. 1
The primary concern is in patients with anatomically narrow angles who lack a patent iridectomy, as the pupillary dilation may trigger an angle closure attack. 1
Pre-existing open-angle glaucoma is NOT a risk factor for angle closure glaucoma and does not increase risk from escitalopram-induced pupil dilation. 1
Reversibility
Yes, the pupil dilation is reversible and resolves when the medication is discontinued. The effect is pharmacologically mediated and not a permanent structural change. While the FDA label does not explicitly state a timeline for resolution, the pharmacokinetics of escitalopram show:
Elimination half-life of 27-33 hours, meaning the drug clears from the system within several days of discontinuation. 2
Steady-state concentrations are achieved within 7-10 days, suggesting that pupillary effects would similarly dissipate within this timeframe after stopping the medication. 2
Clinical Recommendations
The FDA recommends that patients "may wish to be examined to determine whether they are susceptible to angle closure, and have a prophylactic procedure (e.g., iridectomy), if they are susceptible" before starting escitalopram. 1
Practical approach:
Screen patients for narrow angles before initiating escitalopram, particularly those with risk factors (hyperopia, family history, Asian ethnicity). 1
Warn patients about symptoms of acute angle closure: eye pain, blurred vision, halos around lights, headache, nausea. 1
If pupil dilation occurs and is problematic but angle closure is not a concern, the effect will resolve with drug discontinuation over approximately 1-2 weeks based on the drug's elimination kinetics. 2
Important Caveat:
The pupil dilation from SSRIs like escitalopram is distinct from the more pronounced mydriasis caused by direct anticholinergic agents (atropine, scopolamine, tropicamide) or sympathomimetics. 3, 4 The dilation is mild and primarily clinically significant only in the context of angle closure risk, not as a general ophthalmologic concern. 1