text: Hexamethylenetetramine was first introduced into the medical setting in 1895 as a urinary antiseptic. It was officially approved by the FDA for medical use in the United States in 1967. However, it was only used in cases of acidic urine, whereas boric acid was used to treat urinary tract infections with alkaline urine. Scientist De Eds found that there was a direct correlation between the acidity of hexamethylenetetramine's environment and the rate of its decomposition. Therefore, its effectiveness as a drug depended greatly on the acidity of the urine rather than the amount of the drug administered. In an alkaline environment, hexamethylenetetramine was found to be almost completely inactive.
  Hexamethylenetetramine was also used as a method of treatment for soldiers exposed to phosgene in World War I. Subsequent studies have shown that large doses of hexamethylenetetramine provide some protection if taken before phosgene exposure but none if taken afterwards.