Inclusion Criteria:
* Those with ongoing and symptomatic Irritable Bowel Syndrome with Constipation (IBS-C)
* Significant mean worst abdominal pain severity (as defined by the study protocol, which will be shared with results reporting) on a Visual Analog Scale (VAS) pain score during the Phase-in period
* Symptoms present at least 1 day/week in the last 3 months with symptom onset at least 6 months prior to the diagnosis.
* Abdominal pain is not adequately relieved at the time of screening and the time of randomization.
Exclusion Criteria:
* Unrelated active disorder which may involve abdominal pain, such as inflammatory bowel disease, diabetes or unstable thyroid disease.
* Pregnancy, plans to become pregnant, or lactation. Any potential patient of child-bearing potential will complete a pregnancy test at Visit 1 and if the test is positive that individual will be excluded from future participation.
* Any other condition, which in the opinion of the investigator would impede compliance or hinder the completion of the study
* A history of abdominal surgery (other than cholecystectomy or appendectomy)
* Active use of prucalopride, domperidone, alosetron, tegaserod, warfarin, antipsychotic (e.g., Seroquel, Risperdal), antidiarrheal, or frequent (\>2 days/week) use of opioid or antispasmodic medication. Those who frequently use Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) will also be excluded.
* Ongoing use of Selective Serotonin Reuptake Inhibitors (SSRIs), Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs), or any other serotonin-active medications, including tricyclic antidepressants (TCAs). Individuals on chronic SSRI therapy, including escitalopram, at the initial evaluation will not be enrolled in the study.
* Inability to avoid the following medications: tricyclic antidepressants, Monoamine Oxidase (MAO) inhibitors including, intravenous methylene blue, linezolid, and pimozide, as well as triptans, fentanyl, lithium, tramadol, tryptophan, buspirone, amphetamines, and St. John's Wort. - - Participants will be informed that MAO inhibitors cannot be used within 14 days of starting or stopping escitalopram.
* Known hypersensitivity to escitalopram or citalopram including any of the inactive ingredients of these formulations.
* Known allergy to adhesive Electrocardiogram (ECG) electrodes.
* Known angle-closure glaucoma, bipolar disorder, history of seizures or prior suicide attempt or known suicidal thoughts.
* Known QTc prolongation or receiving scheduled therapy with a medication associated with prolongation of QTc (screening to be completed at recruitment as detailed above).
