Nexium Control Gastro-resistant Tablets Nexium Control 20mg Gastro-resistant Tablets treat reflux symptoms such as heartburn & acid regurgitation in adults. Just one tablet a day provides protection for 24 hours, getting to work in just 1 hour. Some people may experience protection from heartburn that day or by the evening, although the full effect may take 2-3 days. It can help return your life to normal in under two weeks, with up to 4 out of 5 nights heartburn-free. The active ingredient in Nexium Control 20mg Gastro-resistant Tablets is esomeprazole, which belongs to a group of medicines called 'proton pump inhibitors'. Unlike antacids & alginates which only target the symptoms of acid that have already leaked up into the oesophagus, esomeprazole works by reducing the amount of acid that your stomach produces to tackle the problem at its source & provide relief, all day & all night.