They can be taken in the same day if they're taken far enough apart. I certainly wouldn't recommend taking them at the same time or even just a few hours apart.
If your doctor prescribed them both for you, he/she should have told you how and when to take them. If you've forgotten, call your doctor or pharmacist for clarification. On the other hand, if they were not prescribed for you, or were not prescribed to be taken on the same day, you shouldn't be taking them at all.