Is long term use of omeprazole dangerous?

Yes. It is not recommended to take Omeprazole for longer than four months at a time. Long-term use can lead to weakening of the stomach lining and increased risk of wrist, hip or spine fracture.
Some side effects. Researchers are studying long term effects of Omeprazole (prilosec) use, because the drug is commonly used and works well in blocking stomach acid. Long term use may lower absorption of calcium, vitamin b12, etc... Older folks may have a higher risk of hip fractures. Stomach acid kills germs, so some infections (such as c. Diff. Diarrhea) may be more likely in a person with suppressed acid.
NO. When ppi were initially introduced there were concerns for long term use of omeprazole.After many year of Omeprazole use we have seen any significant side effects.