Good general physician doctors in Yelahanka Noun. smoking stool syndrome (uncountable) (medicine) A symptom of severe phosphorus poisoning in which stools (feces) laden with phosphorus are passed. What are the symptoms of yellow phosphorus? The clinical effects of acute poisoning with YP have classically been divided into three stages. The initial gastrointestinal (GI) stage is characterized by vomiting, nausea, diarrhea, and abdominal pain, which occur within the first 24 h after ingestion. Laboratory tests are almost normal during this period.