Ingestion, inhalation, or absorption of toxic chemicals. The signs of poisoning from swallowed chemicals include burns around the lips and mouth, excessive salivation, and difficulty swallowing. When cleaning or petroleum products have been swallowed, the breath could have an odor resembling the offending chemical. Signs of chemical poisoning by inhalation include choking, coughing, and headache. Signs of chemical absorption poisoning through the skin include itching and burning at the site of absorption. In all cases of chemical poisoning it is essential to follow the instructions of a poison center professional and to seek emergency medical assistance.