I suppose it varies; what you take, what symtoms you have etc. Some can make people feel tired (those for anxiety) though others are supposed to boost people as depression can make people feel tired all the time.
I think it depends on you and your body - as in how you personally react to them, it's different for everyone. Might be best to have another chat with your GP about this, you might be able to get by without medication, you might just need to do something like exercise, or take a break.