It is important to know the medications that could be toxic in small quantities (such as one pill or a few drops) in a child. If a child has ingested one of these medications or even if clinical suspicion is high that the child may have ingested one of these medications, the patient must be admitted for 24 hours of observation. Opioids, especially long-acting preparations like methadone, can lead to lethal respiratory depression and apnea if a small child ingests one pill. Ingestion of one tablet of sustained release calcium channel and beta-blockers has caused death in children. Long-acting preparations require observation as the onset of symptoms may be delayed. Sulfonylureas, oral hypoglycemic agents, may cause severe life-threatening hypoglycemia. Evaluation includes frequent blood glucose monitoring for 24 hours. Citalopram and escitalopram in sustained release preparations have been reported to cause seizures, QT prolongation, and torsades de pointes. Children who have ingested one pill need to be monitored for 24 hours. Other substances that are potentially lethal in very small doses include cyclic antidepressants, benzocaine, clonidine, phenothiazines, and theophylline. A few drops of oil of wintergreen (methyl salicylate), methanol, or ethylene glycol can also be lethal in a child. Lomotil is a combination of an opioid and atropine; while the respiratory depression from diphenoxylate can be treated with naloxone, there are numerous case reports of delayed onset of symptoms even after an extended period of symptom-free observation. Children may also exhibit delayed onset of atropine intoxication, and death has been reported with ingestion of one pill. Iron overdose can be life threatening, but most poison centers do not make hospital referrals until the ingested dose is greater than 20–60 mg/kg. The amount of iron in vitamins and other preparation varies, but a typical prenatal vitamin contains 65 mg of iron. Iron toxicity is often described in five stages. Stage 1 is the initial symptoms of acute iron poisoning including nausea, vomiting, abdominal pain, and diarrhea. This is followed by the latent stage lasting 6–24 hours. The third stage is the “shock” stage and occurs typically 12–24 hours later. The fourth stage is hepatotoxicity. The fifth stage includes delayed sequelae and includes gastric outlet obstruction and strictures. If a child presents to the hospital and has no symptoms of iron poisoning, then it is safe to discharge the patient home after 6 hours of observation.