Black stool is not a typical side effect of Oflomac Forte. However, a severe stomach infection can sometimes cause bleeding in the digestive tract, resulting in black, tarry stools. It is also important to consider if he has consumed dark foods, blueberries, or iron supplements recently. Because black stool can indicate gastrointestinal bleeding, you should contact your pediatrician immediately for an evaluation. Do not discontinue or alter his medication without medical advice, and seek emergency care if he exhibits other symptoms like severe abdominal pain, vomiting, fever, or extreme lethargy.