 [ Symptoms ] how long does it take to decrease fever after starting antibiotics my husband was diagnosed with sinusitis and early pneumonia he was given a shot of rocephin and then sent home with 7 days of levoquin once daily he took his first dose of levoquin at about 7 pm last night he is still running fevers of 100 4 100 8 how long should it take for his fever to go away he is also having head aches and sore throat unrelieved by motrin 400 mg or tylonol 650 mg how long will it take the antibiotics to relieve these symptoms as well [ Disease ] 24 48 hours depends on whats wrong