The Fe-MgO core-shell morphology is proposed within the single-domain nanoparticle regime as an enhanced magnetically driven hyperthermia carrier. The combinatory use of metallic iron as a core material together with the increased particle size (3765 nm) triggers the tuning of dipolar interactions between particles and allows for further enhancement of their collective heating efficiency via concentration control. A theoretical universal estimation of hysteresis losses reveals the role of dipolar interactions on heating efficiency and outlines the strong influence of coupling effects on hyperthermia opening a novel roadmap towards multifunctional heat-triggered theranostics particles.