I use Fluconazole Polfarmex, a few or several hours after taking the last dose, itchy reddened pustules appeared on the body. Is it an allergic reaction?

An allergic reaction is not excluded, but it is difficult to tell a bystander based on such a brief description. Fluconazole is a synthetic antifungal drug from the group of triazole derivatives. Drugs used to treat skin diseases are agents that often provoke allergies. Since this was the last dose, so if the rash does not disappear within a few days, I encourage you to make an appointment with the attending physician, who will adjust the treatment according to your current clinical condition. If you are unable to get to your primary care doctor, the gdziepolek.pl Service also allows you to obtain a teleconsultation with a doctor: https://www.gdziepolek.pl/telekonsultacja