H2 blockers are a class of medications that reduce the production of stomach acid. They work by blocking the action of histamine on H2 receptors in the stomach lining, which helps alleviate conditions like gastroesophageal reflux disease (GERD) and peptic ulcers. Common examples include ranitidine and famotidine. These medications are available both over-the-counter and by prescription. H2 blockers are generally considered safe for short-term use, but long-term use may lead to side effects such as headaches or gastrointestinal issues. Always consult a healthcare professional before starting any new medication.