How long do I have to use Doreta tablets to completely resolve knee pain?

A comprehensive answer to such a question can only be provided by the attending physician, who is acquainted with your medical documentation and current clinical condition. According to the Summary of Product Characteristics, the maximum analgesic effect of Doreta occurs after about 2 hours. The drug should be used for the shortest possible period, using the lowest effective dose to relieve pain. The length of therapy is ultimately decided by the attending physician. I enclose additional information that may be helpful: https://www.gdziepolek.pl/kategorie/leki-przeciwbolowe https://www.gdziepolek.pl/artykuly/jakie-leki-przeciwbolowe-stosowac https://www.gdziepolek.pl/kategorie/narkotyczne-leki-przeciwbolowe-opioidy