Ask the doctors: It’s crucial to use sterilized water for nasal irrigation

Q: Whenever you talk about neti pots, you include a warning about always using distilled water. It seemed to me like an overreaction, but now there's news that someone died from not doing that. Why would that be, when drinking water is treated and goes through testing?

A: Nasal saline rinse, or nasal irrigation, is a personal hygiene practice using warm, sterilized water to gently clear debris from the nasal passages. The debris can include dirt, dust, bacteria, pollen, dander or other allergens. Nasal irrigation also thins out mucus and moistens the delicate tissues of the sinuses to ease congestion and inflammation.

The practice typically involves the use of a small, spouted vessel, commonly known as a neti pot. You fill it with a saline solution (plain water can be irritating) made with warm, sterile water. With the spout fitted to one nostril, you lean forward and tilt your head, and water flows through the nasal passages and exits the other nostril. Then you repeat this in the other direction. It's crucial that nasal saline rinses use either distilled or sterilized water due to risk of infection.

You are correct that tap water in the United States is filtered and disinfected to kill potential pathogens. However, some bacteria, viruses and other organisms can survive this process, including Naegleria fowleri.

Commonly known as the “brain-eating” bacteria, Naegleria fowleri is actually an amoeba. When ingested in drinking water, Naegleria fowleri dies in stomach acid, but when it enters the body through the nose, it can migrate along the olfactory nerve and reach the brain. Once there, the amoeba quickly begins to multiply and destroy brain tissue. This is a condition known as primary amebic meningoencephalitis (PAM).

Symptoms of PAM appear about five days after infection. It starts with headache, fever, nausea and vomiting. As the infection progresses, it causes confusion, loss of balance, seizures and hallucinations. The destruction of brain tissue, along with the resulting immune response, causes swelling.

This pressure gets so intense that the connection between the brain stem and the spinal cord eventually severs. This is what can lead to death. There are no effective treatments for PAM at this time.

Naegleria fowleri infection of the brain is quite rare. In the U.S., we see fewer than 10 cases each year. Most are infections acquired while swimming in warm freshwater. However, PAM is possible from using tap water for nasal irrigation.

In the recent incident you're referring to, a woman in Texas developed a fatal infection after using tap water from a campground to perform nasal irrigation. So, to repeat the warning that prompted your letter, always use distilled or sterilized water for nasal irrigation.

You can buy sterilized water, or you can sterilize your own tap water by boiling it for three to five minutes then letting it cool.

• Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.

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