This double-blind, randomized, placebo-controlled trial aims to evaluate the efficacy and safety profiles of sodium alginate oral suspension (50mg/ml) 20ml 3 times daily for the treatment of patients with laryngopharyngeal reflux (LPR) in Taiwan. Patients will be enrolled into study if they are at the age of 12 to 75 years old, have at least one symptom consistent with LPR and lasting for more than 4 weeks before study, with a total reflux symptom index (RSI)>10, with a total reflux finding score (RFS)>5, and have signed the informed consent form. Patients will be excluded if they are diagnosed as erosive gastroesophageal reflux disease (GERD)as evidenced by upper GI endoscopy, viral or bacterial laryngitis, or occupational exposures causing laryngitis, laryngeal or hypopharyngeal cancer, esophageal or gastric cancer, with history of neck radiation therapy, with history of esophageal or gastric surgery, with active pulmonary infection (pneumonia, tuberculosis) as evidenced by chest X-ray, with endotracheal tube intubation within 2 months before entering study, or taking any alginate preparations within 2 days; H2-blocker, prokinetic agent or antacid within 7 days; or proton pump inhibitors (PPIs) within 14 days before screening. The primary efficacy endpoint is mean reduction in the total RSI from baseline to Week 8. The secondary efficacy endpoints are mean reduction in the total RSI from baseline to Day 2 and Week 4; mean reduction in the RFS from baseline to Week 4 and Week 8; mean change in the individual component of RSI from baseline to Day 2 , Week 4 and Week 8; mean change in the individual component of RFS from baseline to Week 4 and Week 8; and mean change in the total numbers of reflux episodes as measured by 24-hr ambulatory combined impedance-pH monitoring from baseline to day 2 and week 8. The safety endpoint is incidence of adverse events. The study hypothesis is that sodium alginate is superior over placebo in treating patients with LPR.