Other possible side effects • Experiencing aggression and anger suicidal thoughts or behaviour. • A sensation of restlessness or an inability to sit or stand still, “ Serotonin syndrome” (a rare reaction which may cause feelings of great happiness, drowsiness, clumsiness, restlessness, feeling of being drunk, fever, sweating or rigid muscles), fits or stiffness. • Passing bright red blood in your stools vomiting blood, or black tarry stools (faeces). • Abnormal urine odour. • Yellow colouration of the skin (jaundice), hepatic failure, Stevens-Johnson syndrome, sudden swelling of skin of mucosa (angioedema).