I this study we analyzed three lines, two of which were created by UV- directed mutagenesis and showed increased levels of metronidazole tolerance (M1 and M2) and the third being a line that reverted spontanously to sensitive after several passages (M1NR) of M1 without metronidazole in the media. On the physiological side we analyzed the ability of these lines to reists metronidazole exposure and to encyst as well as their respective doublings times. At the same time we conducted a trasncriptomics and proteomics analysis to understand which exact changes lead to M1 and M2 being resistant while M1NR shows wildtype levels of metrondiazole sensitivty. We than compared these datasets to already existing datasets of other metrondiazole resistant lines and managed to identify a few core changes which are shared between all lines. In all lines proteins that are activating the drug are downregulated while proteins that are part of the oxidative stress response are found in higher abundance. On the other side these core changes are accompanied by a line specific set of changes, showing that there is more than one way for Giardia intestinalis to become resistant to metronidazole.