have a bad effect

have a bad effect (on someone or something)

To affect someone or something adversely. I'm sorry I'm so cranky—this headache is having a bad effect on me. The rain didn't actually have a bad effect on our trip—we all had a lot of fun staying indoors and playing board games.See also: bad, effect, have, someone

have a bad effect (on someone or something)

to be bad for someone or something. Aspirin has a bad effect on me. Cold weather has a bad effect on roses.See also: bad, effect, have