Medications Revolution: Should i use it?

I recently have been looking at revolution for treating mites. I have a guinea pig who has been scratching occasionally, but it is not severe and this has been going on for a while (couple of months, but it seemed normal to me since it was just occasional). I did not think much of it and thought it might be because of his long hair, but I also noticed some yellowish dandruff on his rump. It is only on his rump whereas the rest of his fur seems dandruff free and clean, he has no scabs or any other visible signs. So I cannot know for sure whether he has mites, and due to lack of transportation I cannot take him to a vet to get his opinion.
( (broken link removed) )
But since I have to give him up for adoption I thought it might be safer to just go ahead and treat him with REVOLUTION for puppies and kittens anyway just incase. I was wondering if any of you have used revolution and if it is a safe treatment. ( My main concern is whether or not this will harm him if he has no mites, and if there are any other side affects)