In the case of Zantac, side effects of the drug may include headache, constipation, nausea, and abdominal pain (or stomach pain). Side effects of the medication that are much less common include such things as muscle or joint pain, blurred vision, and insomnia. Rare but serious Zantac side effects may involve trouble breathing or heart problems (such as an increased heart rate).
(Click Zantac Side Effects to learn more about specific side effects that may occur with this medication, including details concerning potentially serious side effects the drug may cause.)