What is Naegleria fowleri?
Naegleria fowleri is a rare, single-celled organism found in warm fresh water and soil that can cause a deadly brain infection if water containing it goes up the nose.
Think of it as a burglar that can only get in through one specific door, the nose. Swallowed, it's destroyed by stomach acid; through the nose, it can travel to the brain.
Why it matters for aging
Infections are extremely rare but almost always fatal. Most cases come from swimming in warm lakes and rivers; a small number have been linked to nasal rinsing with untreated tap water.
The prevention is simple: for nasal rinsing, use only distilled, sterile or boiled-and-cooled water. Ready-made salt packets don't kill the organism.
A common myth
If tap water is safe to drink, it's safe for rinsing your nose.
Drinking water with Naegleria fowleri is harmless, but rinsing your nose with it can be fatal. In 2011, two people in Louisiana died after using neti pots filled with tap water that contained it.
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Updated Nov 9, 2026 · All terms