What are the side effects of prevacid (lansoprazole) for stomach acid?

Headache,: Abdominal pain, diarrhea are the most common (albeit infrequent) short time side effects of prevacid (lansoprazole). Long term, high dose, may be associated with osteoporosis, low magnesium, and perhaps GI infections, but the risk is low. Nonetheless, we recommend using this class of drugs in the lowest dose that will control symptoms. If side effects occur, or symptoms do no resolve, you should see a doctor.