I also wonder how long hyponatremia may set in after taking celexa? i have been taking it for 17 days once a day at 20mg. have also had a mild headache for two days. could the headache be related to the beginning of a case of hyponatremia?

Hyponatremia: Citalopram can cause hyponatremia. It is a cause for SIADH. This condition increases anti-diuretic hormone in your body and can cause dilutional hyponatremia. Signs of hyponatremia would include headache, nausea, confusion, loss of energy, drowsiness or fatigue, restlessness, irritability, muscle cramps, spasm or weakness. Sever hyponatremia can cause seizures and coma.