Hi Harsh, Thanks for writing in. Usual dangerous culprits are: Chlorine and Hydrochloric acid in most toilet bowl cleaners found on store shelves. It was good you did not swallow it which a child could have easily done. There are several cases of poisoning in children. Therefore, first lesson ought to be to keep out of reach of children. Now a day has passed so no effects are expected but anyone swallowing it will have his/her gastrointestinal tract exposed to severe acid leading to chemical pharyngitis, esophagitis, gastritis and enteritis. Which immediately would cause severe pain followed by difficulty in swallowing and in some cases stricture formation. Depending upon the amount, it can theoretically cause perforation of intestines with systemic illness of peritonitis. Fortunately, in accidental poisoning mistake is realised immediately therefore large quantity is not swallowed. More dangerous similar utility item prone to accidental ingestion are air freshners which contain formaldehyde which when absorbed can lead to severe poisoning resulting in blindness and even fatality. Thus the stress about storing housekeeping materials with care. With good wishes Dr Anil Grover Cardiologist