Hello, Thanks for writing your query to us. Ocid (Omeprazole), which is classified as a proton pump inhibitor is used to decrease the production of acid in the stomach. Ocid prevents the activities of stomach enzymes that produce stomach acid. Long-term suppression of stomach acid by ocid may cause side effects. Long-term use of ocid may cause pancreatitis, Pancreatitis is the inflammation of the pancreas, an organ that produces digestive enzymes important for the digestion of fats and carbohydrates. The pancreas also produces insulin, a hormone important in the control of blood glucose levels. Signs and symptoms of pancreatitis include nausea and vomiting, fever, chills, pain in the upper abdomen, fatty stool, rapid heart rate, sweating and rapid breathing. Chronic use of ocid may cause interstitial nephritis, inflammation of the spaces between kidney tubules. Interstitial nephritis reduces the kidneys ability to remove waste products from the body and may eventually lead to kidney failure. Signs and symptoms of interstitial nephritis include decreased urination, sudden weight gain, confusion and changes in mental status, blood in urine, nausea and vomiting. Long-term use of high doses of ocid may lead to increased risk of fractures of the hip, spine and wrists. Patients with bone problems such as osteoporosis should avoid. Your headache is not related to long term use of Ocid. I would advise you that you visit your treating doctor & get your blood pressure checked. Hypertension can also be cause of headache. A thorough clinical examination will know the exact cause of headache. Kindly don’t take any over the counter medicine for long term use. Wish you good health.