Your saliva, tears, and mucus all contain lysozyme, an enzyme that cracks open bacterial cell walls. Supplement forms aim to lend that same defense to your mouth, throat, and immune system. You will find it in lozenges and throat sprays for sore throats or mouth sores, and in capsules for broader immune support.
Check the source if you have an egg or mold allergy. Very high doses sometimes upset the stomach, but no major drug interactions are known.