Frequent Urination on Lexapro and Hyponatremia Risk
Frequent urination while taking Lexapro (escitalopram) does not directly cause hyponatremia through fluid loss; instead, Lexapro itself can cause hyponatremia through SIADH (syndrome of inappropriate antidiuretic hormone secretion), which is unrelated to urination frequency. 1, 2, 3
Understanding the Mechanism
Lexapro causes hyponatremia through SIADH, not through increased urination. The FDA label explicitly warns that "hyponatremia may occur as a result of treatment with SSRIs and SNRIs, including Escitalopram," and "in many cases, this hyponatremia appears to be the result of the syndrome of inappropriate antidiuretic hormone secretion (SIADH)." 1 This mechanism involves your body retaining too much water relative to sodium, paradoxically causing dilutional hyponatremia despite normal or even increased urination. 2, 3
- SIADH causes your kidneys to retain water inappropriately, diluting your blood sodium concentration 1, 2
- The hyponatremia is characterized by serum hypoosmolality, urine hyperosmolality, and elevated urine sodium concentration 2, 4
- Cases with serum sodium lower than 110 mmol/L have been reported with escitalopram 1
Your Specific Risk Profile at Age 61
You are at significantly elevated risk for Lexapro-induced hyponatremia due to your age. The FDA label specifically states that "elderly patients may be at greater risk of developing hyponatremia with SSRIs and SNRIs," and "patients taking diuretics or who are otherwise volume depleted may be at greater risk." 1
- The risk is highest during the first weeks of treatment, with onset typically occurring 6-20 days after starting or increasing the dose 2, 3, 4
- Advanced age is a consistent risk factor across multiple case reports 2, 3, 5, 4
- Lower body weight increases risk 2, 5
- Female gender carries higher risk, though males are also affected 2, 4
Critical Warning Signs to Monitor
You should immediately seek medical attention if you develop any of these symptoms, as they indicate potentially dangerous hyponatremia:
- Headache, difficulty concentrating, memory impairment, confusion, weakness, and unsteadiness (which may lead to falls) 1
- More severe symptoms include hallucination, syncope, seizure, coma, respiratory arrest, and death 1
- Malaise, progressive confusion, or seizures (as seen in documented cases) 2
- Dizziness, falls, decreased strength 4
Recommended Monitoring
Given your age and the 15mg daily dose, you should have your serum sodium checked within the first 2-4 weeks of therapy, especially if you develop any symptoms. 1, 2, 3, 4
- Sodium serum levels should be monitored closely in elderly patients during treatment with escitalopram 2
- The hyponatremia was reversible when escitalopram was discontinued in documented cases 1, 2, 3
- Most cases resolve with discontinuation of the medication and fluid restriction 2, 4
Important Clarification About Urination
Frequent urination is not a typical side effect of Lexapro and does not cause hyponatremia through fluid loss. If you are experiencing genuinely increased urination frequency (polyuria), this warrants separate evaluation for other causes such as diabetes, diabetes insipidus, or other metabolic conditions unrelated to the Lexapro. 6 The hyponatremia risk from Lexapro comes from SIADH causing water retention, not from losing sodium through increased urination.
Critical Pitfall to Avoid
Do not assume that drinking more water will help if you develop symptoms—this can actually worsen SIADH-induced hyponatremia. The FDA label advises patients to "avoid excessive consumption of hypotonic fluids, which can cause hyponatremia" when on diuretics, and the same principle applies to SIADH. 6 Treatment typically involves fluid restriction and discontinuation of escitalopram, not increased fluid intake. 2, 4