Proton pump inhibitors medications like Prevacid (lansoprazole) are strong inhibitors of the stomach's acid production. As such, they are an important part of early treatment of stomach and duodenal ulcers, where they help to speed healing. It sounds like your gastroenterologist
now thinks that your ulcer has healed sufficiently that you do not need to take the medication on a daily basis, which is good news.
Although Prevacid and medications like it are generally quite safe, there are a few side effects that your doctor monitors for. One of these is that occasionally these medications can cause impaired absorption of vitamin B12 in the body, which can lead to anemia and other problems. Similarly, there is some evidence regarding risk for osteoporosis and osteoporosis-related bone fractures. This may be because of impaired absorption or handling of calcium and vitamin D and, for this reason, some doctors
will prescribe these supplements to people who are taking medications like Prevacid for a long time.
Please speak with your primary care doctor
or your gastroenterologist about your concerns about Prevacid related vitamin deficiencies. They will be able to tell you whether or not you need to take any vitamin supplements or perform any testing to look for deficiencies.