The drugs they have taken have caused them to lose their mind/minds.

[Tan Elaine]

The drugs they have taken have caused them to lose their mind/minds.

Which word in bold should I use? Thanks.

 

[MikeNewYork]

The drugs they have taken have caused them to lose their mind/minds.

Which word in bold should I use? Thanks.

I would use "minds" because there are multiple people.

 

[Tan Elaine]

Thanks, Mike.

Do we say "They raised their hand" or "They raised their hands"?

 

[MikeNewYork]

Thanks, Mike.

Do we say "They raised their hand" or "They raised their hands"?

Either way, one could have a problem.
Since people have two hands, the plural could mean that each of them raised two hands. But the singular is worse. That suggests that the people all shared one hand. I would go with the plural or rephrase the sentence.

 

[Tan Elaine]

Thanks, Mike.

How would you rephrase the sentence?

 

[MikeNewYork]

Thanks, Mike.

How would you rephrase the sentence?

You could say "Each of them raised their (or his/her) hand."