Antibiotics　usually　induce　the　hormetic　effects　on　bacteria,　featured　by　low-dose　stimulation　and　high-dose　inhibition,　which　challenges　the　central　belief　in　toxicity　assessment　and　environmental　risk　assessment　of　antibiotics.　However,　there　are　currently　no　ideal　parameters　to　quantitatively　characterize　hormesis.　In　this　study,　an　effective　area　in　hormesis　(AH)　was　developed　to　quantify　the　biphasic　dose-responses　of　single　antibiotics　(sulfonamides　(SAs),　sulfonamides　potentiators　(SAPs),　and　tetracyclines　(TCs))　and　binary　mixtures　(SAs-SAPs,　SAs-TCs,　and　SAs-SAs)　to　the　bioluminescence　of　Aliivibrio　fischeri.　Using　Ebind　(the　lowest　interaction　energy　between　antibiotic　and　target　protein)　and　Kow　(octanol-water　partition　coefficient)　as　the　structural　descriptors,　the　reliable　quantitative　structure-activity　relationship　(QSAR)　models　were　constructed　for　the　AH　values　of　test　antibiotics　and　mixtures.　Furthermore,　a　novel　method　based　on　AH　was　established　to　judge　the　joint　toxic　actions　of　binary　antibiotics,　which　mainly　exhibited　synergism.　The　results　also　indicated　that　SAPs　(or　TCs)　contributed　more　than　SAs　in　the　hormetic　effects　of　antibiotic　mixtures.　This　study　proposes　a　new　quantitative　parameter　for　characterizing　and　predicting　antibiotic　hormesis,　and　considers　hormesis　as　an　integrated　whole　to　reveal　the　combined　effects　of　antibiotics,　which　will　promote　the　development　of　risk　evaluation　for　antibiotics　and　their　mixtures.　©　2024　Elsevier　B.V.