Hi Michelle,   Nexium (brand name for ESOMEPRAZOLE) is a PPI, or proton pump inhibitor. It is possible there is something in Nexium that isn't working for you,  and it might be wise to discuss with your doctor about alternative PPI's. You can read about Nexium here in the drugs database. There is mention of the following side effects.   "Headache, diarrhea, nausea, gas, stomach pain, constipation, or dry mouth may occur. If any of these effects persist or worsen, notify your doctor or pharmacist promptly." You can read more about the side affects here.   You also mention that you have a hiatal hernia. You can get some information about Hiatal Hernia's here and read about prevention and treatments here.   Take care and stay in touch, let us know how you are doing!Vicki M