hello, i can understand your concern. i would like to know the weight of your daughter the usual effects of over dose of cephalexin are diarrhea, vomitings, nausea, epigastric distress, hematuria etc. yourdoesnt seem to have any of these. with none of these present abdominal decontamination is not required in this case. mild weakness and loss of apetite can be seen even with normal dosage of the drug. the vital parameters like pulse, blood pressure, respiration and urine out put should be monitored. i would suggest you to consult the treating physician and get your daughter checked for all the vital parameters and if required can be treated accordingly. the dosage which you have given is not lethal, so do not worry. please make sure to read the doctor instructions and the instructions mentioned on the drugs prior to its usage especially for children. hope i have answered your concerns. feel free to ask further queries. thanks for choosing HCM.