A 62-year-old man with a known history of type 2 diabetes mellitus and hypertension presents to his GP with a 3-day history of a painful, red, swollen right great toe. He denies any recent trauma. On examination, the metatarsophalangeal joint of the right great toe is erythematous, warm, tender, and swollen. Serum uric acid level taken last month was 0.52 mmol/L (normal range 0.22-0.48 mmol/L). What is the most appropriate initial management?