Other possible side effects • Hallucinations, suicidal thoughts, behaviour aggression and anger. • A sensation of restlessness or an inability to sit or stand still or “ 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. • Passing bright red blood in your stools, vomiting blood, or black tarry stools (faeces). • Having abnormal urine odour. • Chest pain. • Yellow colouration of the skin (jaundice), hepatic failure, Stevens-Johnson syndrome, sudden swelling of skin or mucosa (angioedema).