Prozac capsule is available in different doses, like; Prozac 5 mg, Prozac 10 mg, Prozac 20 mg, Prozac 40 mg, and Prozac 60 mg. The lowest dose of the medicine is Prozac 5 mg. All these available medications are taken by mouth with water. The doctor prescribes to the patient the initial dose is 5 mg of Prozac for the patient.