Since the beginning of the coronavirus pandemic in late 2019, viral infections have become one of the top three causes of mortality worldwide. Immunization and the use of immunomodulatory drugs are effective ways to prevent and treat viral infections. However, the primary therapy for managing viral infections remains antiviral and antiretroviral medication. Unfortunately, these drugs are often limited by physicochemical constraints such as low target selectivity and poor aqueous solubility. Although several modifications have been made to enhance the physicochemical characteristics and efficacy of these drugs, there are few published studies that summarize and compare these modifications. Our review systematically synthesized and discussed antiviral drug modification reports from publications indexed in Scopus, PubMed, and Google Scholar databases. We examined various approaches that were investigated to address physicochemical issues and increase activity, including liposomes, cocrystals, solid dispersions, salt modifications, and nanoparticle drug delivery systems. We were impressed by how well each strategy addressed physicochemical issues and improved antiviral activity. In conclusion, these modifications represent a promising way to improve the physicochemical characteristics, functionality, and effectiveness of antivirals in clinical therapy.