Described are compositions and methods for inhibiting polymerization of a monomer (e.g., styrene) composition, which use an N—O polymerization inhibitor, a quinone methide polymerization retarder, and an amine stabilizer having a primary and/or secondary amine group. In a mixture, the amine-based stabilizer can prevent antagonistic effects and can provide greater antipolymerant activity. In turn, the mixture inhibits apparatus fouling and improves the purity of monomer streams.