The immersion bathtub should be filled with about 135 litres of hot water at 40ºC. One to 1 1/2 kg of Epsom salt should be dissolved in this water. The patient should drink a glass of cold water, cover the head with a cold towel and then lie down in the tub, completely immersing the trunk, thighs and legs for 15 to 20 minutes. The best time to take this bath is just before retiring to bed.