I have developed a gastritis after my bout of PMR and treatments. Gastroenterologist started me on Famotidine 40mg. This is OTC for the 20mg dosage. I try to take it as needed but it works better to just take every day. I found I am able to take just the one 40mg tablet daily with reasonable success. I think the prescription says up to 4 tablets daily. I have not seen any side effects at the lower dosage.