  Close to the Fermi energy, nodal loop semimetals have a torus-shaped,
strongly anisotropic Fermi surface which affects their transport properties.
Here we investigate the non-equilibrium dynamics of nodal loop semimetals by
going beyond linear response and determine the time evolution of the current
after switching on a homogeneous electric field. The current grows
monotonically with time for electric fields perpendicular to the nodal loop
plane however it exhibits non-monotonical behavior for field orientations
aligned within the plane. After an initial non-universal growth $\sim Et$, the
current first reaches a plateau $\sim E$. Then, for perpendicular directions,
it increases while for in-plane directions it decreases with time to another
plateau, still $\sim E$. These features arise from interband processes. For
long times or strong electric fields, the current grows as $\sim E^{3/2}t$ or
$\sim E^3t^2$ for perpendicular or parallel electric fields, respectively. This
non-linear response represents an intraband effect where the large number of
excited quasiparticles responds to the electric field. Our analytical results
are benchmarked by the numerical evaluation of the current from continuum and
tight-binding models of nodal loop semimetals.
