Formaldehyde is a gas that dissolves in water, resulting in a formalin solution. In the atmosphere, formaldehyde gas is very irritating and causes coughing, tearing, eye burning and pain, bronchial irritation and pulmonary edema. If a subject ingests formalin, it acts as a corrosive agent.
Treatment
Reactions to vapors should be treated symptomatically, with the certainty of avoiding further exposure. When formaldehyde is ingested, the treatment to be used is the same as for corrosive poisoning.
Source: Vadecum of poisoning therapy by Roy Goulding