Algin (alginate, alginic acid) is a complex carbohydrate taken from brown seaweed. Mix it with water and it turns into a thick gel. That gel floats on top of stomach contents, forming a physical barrier that blocks acid from washing back up into the esophagus.
People use it after meals or before bed to manage occasional heartburn and acid reflux. Liquids, chewable tablets, and powders mixed with water are the most common forms.
A few cautions apply. Algin can slow how the body absorbs other medicines, so leave at least two hours between doses. It carries a small amount of iodine, which might influence thyroid function. Steer clear if you have trouble swallowing or a history of bowel obstruction. Pregnant or nursing women should speak with a healthcare professional.