Can systemic parenteral ozone therapy generate biological ozone? A new hypothesis

•There are chemical reaction mechanisms that produce ozone from singlet oxygen.•Medical ozone forms ROS which by interconversion reaction produces singlet oxygen.•Parenteral ozone therapy could form endogenous ozone. Since the first years of this century, evidence of the generation of singlet oxygen and endogenous ozone from antibodies and some amino acids has been reported. Different mechanisms of action have been proposed which provide appropriate pathways that scientifically justify their approval. On the other hand, parenteral systemic ozone therapy is known to produce reactive oxygen species (ROS) that by chemical interconversion could form singlet oxygen, which is the precursor to trigger the formation of endogenous ozone. This article analyzes the latest evidences reported on the generation of biological ozone, and highlights the hypothesis that ROS resulting from the application of parenteral ozone therapy can also lead to the endogenous formation of ozone or an oxidant like ozone. Future confirmation of this approach would be another justification for the usefulness of ozone therapy in the treatment of diseases such as viral ones and antibiotic resistance. [Display omitted]