  At finite concentrations of reacting molecules, kinetics of
diffusion-controlled reactions is affected by intra-reactant interactions. As a
result, multi-particle reaction statistics cannot be deduced from
single-particle results. Here we briefly review a recent progress in overcoming
this fundamental difficulty. We show that the fluctuating hydrodynamics and
macroscopic fluctuation theory provide a simple, general and versatile
framework for studying a whole class of problems of survival, absorption and
escape of interacting diffusing particles.
