From
WebMD:
Take this medication by mouth after meals with a full glass of water (8 ounces or 240 milliliters) or as directed by your doctor.
To prevent stomach upset, your doctor may recommend a slow increase in your dosage when starting treatment. Dosage is based on your medical condition and response to therapy.
Here's another suggestion my GI made - since I take 3 tablets of sulfazine every day, he encouraged me to split it into one in the morning and two at night. That way, he said, if I got a headache I'd sleep through most of it. I have found this to be mostly true - I wake up with a headache more times than I'd like, but it responds to tylenol and I get on with my day.