As for stomach upset it depends on the cause. With some medications that cause this taking food or milk with them can be helpful. Also sometimes there is an extended release or coated form. It depends on the medication. As regarding nausea I could not tolerate lithium (as an example) but the coated/extended release brand Lithobid was fine. Ask your psychiatrist about options. The same as regards effect on sex drive which varies. "Depression Central" is a good website that has information you could discuss with your psychiatrist.
If you have a psychiatrist, I would sit down and way out which may work better. If you don't have one, then it's in your best interest to get one, GP's don't know alot about psychopharmaceuticals. I've been on many of the SSRI's and most gave me headaches and killed my sex drive. You may want to look into a different class of drugs called Mood Stabilizers - if you haven't already, also depending on your diagnosis, which you didn't post. Some meds upset your stomach at first but that symptom does go away. It's a bit of patience trying to get the right one, or combinations of meds.