Four-month-old babies with brown mucus stools need to consider physiological and pathological causes. Such as cold, taking iron and other physiological causes, do not need special treatment; such as enteritis, intestinal flora imbalance, intussusception and other conditions, may need to consider medication (such as Lactobacillus acidophilus tablets, Bacillus licheniformis capsules), air enema treatment and other measures. 1. Physiological causes and treatment: e.g. cold can cause abnormal digestive function in babies; e.g. breastfed babies may also develop this condition if their mothers take iron supplements or consume something blood products. This kind of situation usually do not need special treatment, can recover by themselves. 2. Pathological causes and treatment: the baby mostly manifested as crying, unwilling to breastfeed, etc., need to be combined with routine blood, stool routine, abdominal plain film and other tests for identification. For enteritis can consider cephalosporin antibiotics; for intestinal flora dysbiosis can consider lactobacillus acidophilus tablets, bacillus licheniformis capsules, etc.; for intussusception can consider the air enema treatment, if necessary, surgical treatment. For the treatment of four-month-old babies with brown mucus stools, it is recommended to consult a doctor as soon as possible, and give appropriate treatment after the cause is clarified.