Can Celexa (citalopram) cause hyponatremia?

Citalopram (Celexa) Can Cause Hyponatremia

Yes, Celexa (citalopram) can cause hyponatremia, particularly in elderly patients, with onset typically within the first month of treatment. This is a well-documented adverse effect of selective serotonin reuptake inhibitors (SSRIs) including citalopram.

Mechanism and Risk

Citalopram-induced hyponatremia is primarily caused by:

• Syndrome of Inappropriate Antidiuretic Hormone secretion (SIADH) 1
• Risk is higher in:
  • Elderly patients (particularly those over 65 years)
  • Female patients
  • Patients with low body weight
  • Patients taking diuretics or who are volume depleted 2, 1

Incidence and Timing

• Hyponatremia occurs in approximately 0.5% to 12% of older adults taking SSRIs 3
• SSRIs have a significantly higher risk of causing hyponatremia compared to other drug classes (OR = 3.3; 95% CI, 1.3 to 8.6) 3
• Most cases develop within the first month of treatment 4
  • In 84% of reported cases, hyponatremia was detected during the first month of citalopram therapy 4

Clinical Presentation

Patients with citalopram-induced hyponatremia may present with:

• Headache
• Difficulty concentrating
• Memory impairment
• Confusion
• Weakness
• Unsteadiness (which may lead to falls)

In severe cases:

• Hallucinations
• Syncope
• Seizures
• Coma
• Respiratory arrest 1, 5

Case Reports and Evidence

Multiple case reports have documented severe symptomatic hyponatremia with citalopram:

• A 61-year-old diabetic male developed confusion and seizures two weeks after starting citalopram 20 mg/day, with sodium levels dropping to 124 mmol/L 5
• An 88-year-old woman with chronic hyponatremia developed acute symptomatic hyponatremia when naproxen was added to her citalopram regimen 6
• A 92-year-old woman developed severe hyponatremia with coma, seizure, and atrial fibrillation after only two doses of citalopram 4

Management Recommendations

1. Monitor sodium levels in high-risk patients:

   • Check baseline sodium before starting citalopram
   • Recheck within 2-4 weeks of initiation, particularly in elderly patients 2
   • Continue monitoring throughout treatment course 7

2. If hyponatremia develops:

   • Discontinue citalopram if symptomatic hyponatremia occurs 1
   • Institute fluid restriction (typically to 1,000 mL/day) for mild cases 2
   • For moderate to severe cases, more aggressive management may be needed
   • Ensure correction rate does not exceed 8 mmol/L per day to prevent central pontine myelinolysis 2

3. Prevention:

   • Consider alternative antidepressants in patients with history of hyponatremia
   • Use caution when combining citalopram with other medications that can cause hyponatremia (e.g., diuretics, NSAIDs) 6

Clinical Pearls and Pitfalls

• Hyponatremia may recur when switching between different antidepressants, even those thought to be safer (e.g., mirtazapine) 7
• Polymedication and concomitant use of other psychotropic drugs or thiazide diuretics may increase the risk 4
• Symptoms may be mistaken for worsening depression or cognitive decline in elderly patients
• Routine sodium monitoring is not performed frequently enough in clinical practice, leading to delayed diagnosis

Clinicians should maintain a high index of suspicion for hyponatremia in any patient taking citalopram who presents with new neurological symptoms, especially in the elderly population.