Context :

Aims : We aim to study the short-term evolution of the chromospheric and photospheric activity of the young , single K2 dwarf LQ Hya .

Methods : Four months of quasi-simultaneous spectroscopic and photometric observations were used to study the variations of the photometric light curve , the evolution of the chromospheric activity from the H \alpha and H \beta lines , and the distribution of cool spots from Doppler maps .

Results : During our observations one side of the star was more active than the other .
The equivalent width of the H \alpha line from the least active hemisphere increased from \approx 0.7 Å at the beginning of the observation to 1.0 Å at the end .
The basal emission of the most active hemisphere remained roughly constant at EW _ { \mathrm { H \alpha } } \thickapprox 1.0 Å .
Intense flare activity was observed during the first twenty days , where at least four different events were detected .
The line asymmetries of the H \alpha line suggest that one of the flares could have produced a mass ejection with a maximum projected speed of \mathrm { 70 \thinspace km \thinspace s ^ { -1 } } .
The rotational modulation of the V -band photometry showed clear anti-correlation with the chromospheric activity .
The difference in brightness between the opposite hemispheres decreased from 0 \aas@@fstack { m } 16 to 0 \aas@@fstack { m } 09 in two months .
Three spots gradually moving apart from each other are dominating the photospheric Doppler maps .
The comparison between the maps and the H \alpha line as the star rotates reveals the spatial coexistence of chromospheric H \alpha emission and photospheric spots .

Conclusions : Our results indicate that the active regions of LQ Hya can live for at least four months .
The detected changes in the photometric light curve and the spectroscopic Doppler images seem to be more a consequence of the spatial redistribution of the active regions rather than due to changes in their strength .
Only one of the active regions shows significant changes in its chromospheric emission .