Reactive oxygen species (ROS) play a crucial role in antimicrobial strategies, including bactericidal antibiotics, photodynamic therapy, and other methods like titanium dioxide photocatalysis and medicinal honey. ROS, such as superoxide (O₂⁻), hydrogen peroxide (H₂O₂), hydroxyl radicals (·OH), and singlet oxygen (¹O₂), are produced through various metabolic processes and have different reactivities and toxicities. While O₂⁻ and H₂O₂ are less reactive and can be neutralized by antioxidants, ·OH and ¹O₂ are highly toxic and can cause rapid cell death. The review highlights the mechanisms of ROS formation, their role in host defense, and the use of ROS in antimicrobial therapies. It also discusses antioxidant defenses in microbial cells and the use of ROS by host defense systems. Antimicrobial approaches include bactericidal antibiotics and non-pharmacological methods such as photodynamic therapy, titanium dioxide photocatalysis, cold plasma, and medicinal honey. The review also briefly covers reactive nitrogen species and related therapeutics. ROS are produced in various cellular processes, including mitochondrial respiration, cytochrome P450 metabolism, and inflammatory responses. ROS can damage cellular components, leading to oxidative stress and disease. Antioxidant defenses, including enzymes like SOD, catalase, and glutathione peroxidase, help neutralize ROS. Bacteria have evolved mechanisms to respond to oxidative stress, including the OxyR and SoxRS regulons, which regulate the expression of detoxifying enzymes. The review emphasizes the importance of understanding ROS in antimicrobial strategies and the development of new therapeutic approaches to combat infections.Reactive oxygen species (ROS) play a crucial role in antimicrobial strategies, including bactericidal antibiotics, photodynamic therapy, and other methods like titanium dioxide photocatalysis and medicinal honey. ROS, such as superoxide (O₂⁻), hydrogen peroxide (H₂O₂), hydroxyl radicals (·OH), and singlet oxygen (¹O₂), are produced through various metabolic processes and have different reactivities and toxicities. While O₂⁻ and H₂O₂ are less reactive and can be neutralized by antioxidants, ·OH and ¹O₂ are highly toxic and can cause rapid cell death. The review highlights the mechanisms of ROS formation, their role in host defense, and the use of ROS in antimicrobial therapies. It also discusses antioxidant defenses in microbial cells and the use of ROS by host defense systems. Antimicrobial approaches include bactericidal antibiotics and non-pharmacological methods such as photodynamic therapy, titanium dioxide photocatalysis, cold plasma, and medicinal honey. The review also briefly covers reactive nitrogen species and related therapeutics. ROS are produced in various cellular processes, including mitochondrial respiration, cytochrome P450 metabolism, and inflammatory responses. ROS can damage cellular components, leading to oxidative stress and disease. Antioxidant defenses, including enzymes like SOD, catalase, and glutathione peroxidase, help neutralize ROS. Bacteria have evolved mechanisms to respond to oxidative stress, including the OxyR and SoxRS regulons, which regulate the expression of detoxifying enzymes. The review emphasizes the importance of understanding ROS in antimicrobial strategies and the development of new therapeutic approaches to combat infections.