Protonix (Pantoprozole) does not give me problems...maybe a little weight loss. Omeprazole (Prilosec or Zegerid) causes me all kinds of problems. Headache, chest pain, red/irritated eyes, all kinds of body aches, constipation and extreme thrist. Problem is...protonix is by script only and VERY EXPENSIVE! Someone talk to me about this. Has anyone else experienced these problems with Omeprazole?