What is the primary use of formaldehyde in the medical field?

Formaldehyde's primary use in the medical field is as a preservative in biological specimens. This compound is utilized extensively in laboratories and research settings to prevent the decay of tissues and organs by inhibiting microbial growth and autolysis. Its ability to cross-link proteins makes it effective at preserving the structure of cells and tissues, allowing for better study and examination under a microscope.

In contrast, the other options focus on purposes that formaldehyde does not serve. It is not used as a sedative, pain reliever, or antibiotic, as those roles are filled by specific medications designed to alleviate symptoms or treat infections. Being aware of the distinctive applications of substances in medical settings is crucial for proper practices and patient safety.