Pharmacology: Paracetamol Infusion provides onset of pain relief within 5 - 10 minutes after the start of administration.The peak analgesic effect is obtained in 1 hour and the duration of this effect is usually 4 - 6 hours. Paracetamol Infusion reduces fever within 30 minutes after the start of administration with a duration of the antipyretic effect of at least 6 hours.