Oxidative stress is an imbalance between free radicals and antioxidants in your body. Free radicals are oxygen-containing molecules with an uneven number of electrons. The uneven number allows them to easily react with other molecules. Free radicals can cause large chain chemical reactions in your body because they react so easily with other molecules. These reactions are called oxidation. They can be beneficial or harmful.
Reference: Written by Megan Dix, RN, BSN, Medically reviewed by Timothy J. Legg, PhD, CRNP, https://www.healthline.com/health/oxidative-stress consulted on july 08th,2019