Acid blockers also called histamine (H-2) blockers reduce the amount of acid released into your digestive tract, which relieves gastritis pain and encourages healing. Available by prescription or over the counter, acid blockers include famotidine (Pepcid), cimetidine (Tagamet HB) and nizatidine (Axid AR). Your doctor may include an antacid in your drug regimen. Antacids neutralize existing stomach acid and can provide rapid pain relief. Side effects can include constipation or diarrhea, depending on the main ingredients. These help with immediate symptom relief but are generally not used as a primary treatment. Proton pump inhibitors and acid blockers are more effective and have fewer side effects. Proton pump inhibitors reduce acid by blocking the action of the parts of cells that produce acid. These drugs include the prescription and over-the-counter medications omeprazole (Prilosec), lansoprazole (Prevacid), rabeprazole (Aciphex), pantoprazole (Protonix) and others. Long-term use of proton pump inhibitors, particularly at high doses, may increase your risk of hip, wrist and spine fractures. Ask your doctor whether a calcium supplement may reduce this risk.