The phrase "worst effects" refers to the most negative or harmful outcomes or consequences. It signifies the outcomes that are considered the most undesirable or upsetting. Full definition
Also, doctors are afraid of bad effects of fasting because they don't know better. (idmprogram.com)
The reasons are similar to the reasons you shouldn't be late but this will have even worse effects on your arrangement. (sugardaddysite.us)
I don't recommend using a template for a Cover letter as the formatting in templates can have bad effects if copied into email. (resumetemplatesformac.com)