What kills bad bacteria in the body naturally?

What kills bad bacteria in the body naturally is primarily your immune system and beneficial microbes that work together constantly without antibiotics. Your innate immune system includes white blood cells like neutrophils and macrophages that patrol blood and tissues and engulf and digest harmful bacteria through phagocytosis, and natural killer cells that destroy infected cells. Your skin and mucous membranes produce antimicrobial peptides like defensins and cathelicidins that puncture bacterial walls. Lysozyme in tears, saliva, and mucus breaks down bacterial cell walls, stomach acid with pH 1.5 to 3.5 kills most ingested bacteria, and beneficial gut bacteria compete with bad bacteria for nutrients and produce substances like lactic acid that inhibit them. Fever helps because many bad bacteria grow best at normal temperature and immune cells work better at slightly higher temperature. Foods like garlic containing allicin, honey producing hydrogen peroxide, and yogurt with probiotics have mild antibacterial effects that support this natural killing, but are not strong enough to cure serious infections alone. To support natural killing, get adequate sleep 7 to 9 hours, stay hydrated, eat protein and zinc rich foods for antibody production, manage stress, and maintain good indoor air quality with HEPA filtration to reduce airborne bacterial load. For serious bacterial infections with fever, pus, or persistent pain, natural killing may be overwhelmed and you need medical antibiotics to prevent spread to bloodstream and sepsis.