Mirtazapine is a novel antidepressant which is used for the treatment of major depression. It works via alpha-2 adrenergic antagonism to enhance noradrenergic and serotonergic neurotransmission. Studies have shown mirtazapine to have outstanding safety profile. Common adverse effects of mirtazapine are increased appetite, weight gain, dry mouth, drowsiness and constipation. There are very few reported cases and literature to suggest the link between mirtazapine use and development of peripheral edema. The mechanism by which mirtazapine causes peripheral edema is not clearly known. This abstract describes a case of 40years old male who presented to the psychiatry outpatient department with complaints of feeling anxious, having negative thoughts and difficulty initiating sleep for 1 month duration. He was started on mirtazapine 7.5mg after which, his symptoms gradually improved. However, 2 months into the treatment, the patient complained of swelling of bilateral lower limbs. On examination, bilateral pitting edema was evident from pre-tibial region to the foot. Routine blood investigations that included haematology, blood glucose, thyroid, liver and renal functions were normal. Venous doppler of bilateral lower limbs were also done which yielded no pathology.

Therefore, suspecting that the bipedal edema was due to mirtazapine, it was stopped. Patient claimed that two to three days after cessation of mirtazapine, the swelling reduced. On examination after 2 weeks, the bipedal edema had markedly reduced, which completely subsided after a month of stopping mirtazapine. However, re-challenge with mirtazapine was not done and serum mirtazapine level was not measured either. Naranjo scale was applied that yielded a score of 7, which indicates that bipedal edema in this case was probably due to mirtazapine. With this article, we aim to discuss the probability of peripheral edema during the treatment course of mirtazapine which will be of utmost use to the prescribing physician.

Keywords: Antidepressant, Mirtazapine, Peripheral edema, Side effect