If your ankles swell during the Summer months due to heat, humidity, and tight-strapped sandals try to get comfortable again FAST by soaking your painful feet in a basin filled with 2 liters of chilled tonic water for 15 minutes. The quinine in the tonic water is anti-inflammatory so it will bring down the swelling while the cold water constricts the blood vessels so the fluids in your body have less room to collect.