Otsuka Pharmaceutical Factory OS-1 Jelly 200g Oral Rehydration Solution OS-1 Jelly is an oral rehydration solution used for dietary therapy (oral rehydration therapy) for dehydration. It is a food for those with illnesses, suitable for the supplementation and maintenance of water and electrolytes in mild to moderate dehydration. This product is new and unopened, but it has been stored at home. Please refrain from purchasing if you are concerned about this.