Background: As a national policy all Iranian children under two-years-old should consume oral supplements such as iron, A+D vitamin, and multivitamin drops. Sugars and acids are widely used in pediatric medications including supplements, and long-term consumption of these drugs is associated with higher risk of dental decay and erosion. Consideraing the importance of nutritional supplementation for children, and the lack of research regarding sugar type, amount of acidity and viscosity of Iranian medications, the aim of the present study is to determine the sugar type, pH, and viscosity in common nutritional supplements in children. Materials and methods: In this experimental study, we extract the first fifty liquid pediatric medications (more than a million pack sales in one year), according to the Pharmaceutical Statistics of Food and Drug Administration of the Islamic Republic of Iran. By asking pediatricians from Childern’ s Medical Center and Phamacists from the selected pharmacies in Tehran, the most prescribed and sold pediatric liquid oral supplements were determined. Filnally we selected 24 supplements and two samples of each medicine were provided. In the next step we determined the sugar type based on labeling information, the pH using the pH meter pp-15 device, and the viscosity by Dial Reading Viscometer device. The data were analyzed by descriptive statistical methods. Results: From 24 supplements, only six medications offered information about the sugar component (sodium saccharin) and the others provide none information. In terms of the acidity of the drugs, all drugs placed in the critical pH (lower than 5. 5). The mean of pH in AD drops, iron drops, multivitamin drops, and other supplements were 4. 12, 1. 9, 3. 2, and 4, respectively. In addition, the mean of viscosity in all medications was low and desirable, which in millipascal-second (mPa-s). level. The mean of viscosity in AD drops, iron drops, multivitamin drops, and other supplements were 38. 1, 22. 4, 38. 6, and 27. 3 mPa-s, respectively. Conclusion: Due to the lack of appropriate information on the labeling of the supplements, the pharmaceutical companies should offer sufficient information about their products to increase the awareness of parents to choose supplements with less risk of dental caries. Considering the pH was lower than the critical level in all medications, providing necessary standards by the pharmaceutical companies enjoys a special importance. In addition, applying the preventive dental care after supplements consumption by parents should be adviced. Due to the favorable viscosity levels of the supplements, it seems that the pH of the drug is the most important factor regarding dental caries and erosion