Saline Nasal Irrigation: A Simple Intervention With Real Evidence

One of the few interventions in this whole field that is cheap, well-evidenced and almost free of downside — with one important safety caveat.

Why it works

Saline irrigation is mechanical rather than pharmacological, which is part of why it is so well tolerated.

Physical removal. Flushing the nasal cavity removes mucus, trapped allergens, particulates and inflammatory mediators. In allergy season this means physically removing deposited pollen rather than waiting for it to be cleared.

Improved mucociliary function. Saline thins secretions and hydrates the mucosal surface, both of which support ciliary clearance.

Reduced inflammatory mediator load. Washing out histamine, leukotrienes and prostaglandins reduces the local inflammatory drive.

Improved crust and debris clearance, which matters after surgery or in dry environments.

The evidence

This is one of the better-evidenced simple interventions in respiratory care. Saline irrigation appears in clinical guidelines for chronic rhinosinusitis and for allergic rhinitis, supported by systematic review evidence for symptom improvement.

It is also used routinely following sinus surgery, and in paediatric populations where pharmacological options are more constrained.

The effect sizes are modest rather than dramatic, but the intervention is inexpensive, has minimal adverse effects, and is additive with pharmacological treatment rather than competing with it.

The water safety point

This is the one genuinely important safety issue and it is not a formality.

Never use untreated tap water. Tap water is safe to drink because stomach acid handles the organisms it may contain. The nasal cavity has no such defence.

There have been documented fatal cases of primary amoebic meningoencephalitis from Naegleria fowleri introduced during nasal irrigation with untreated water. It is rare and it is almost always fatal.

Use one of: distilled water, water labelled sterile, or tap water that has been boiled for at least one minute and cooled. Boiling and cooling is free and entirely adequate.

Clean the device after every use and let it air dry completely.

Isotonic vs hypertonic

Isotonic saline matches the salt concentration of body fluid, roughly 0.9 percent. It is gentler and better tolerated for regular daily use.

Hypertonic saline is more concentrated, typically 1.5 to 3 percent. It draws fluid osmotically from swollen mucosa, which can reduce congestion more effectively, and some evidence suggests better mucociliary effects. It also stings more and is less well tolerated long term.

A reasonable approach: isotonic for daily maintenance, hypertonic during acute congestion if you tolerate it.

Adding a small amount of bicarbonate buffers the solution and reduces stinging noticeably.

How to do it

1. Prepare the solution — use a commercial sachet with the correct water, or make isotonic saline with roughly half a teaspoon of non-iodised salt plus a pinch of bicarbonate per 250 ml of appropriate water.
2. Use lukewarm solution. Cold stings; hot is unsafe.
3. Lean forward over a sink and turn your head to one side.
4. Insert the spout into the upper nostril and let solution flow in, draining from the lower nostril.
5. Breathe through your mouth throughout.
6. Use roughly half the volume per side.
7. Blow gently afterward. Forceful blowing can push fluid into the ears.
8. Clean and dry the device.

When not to use it

• Complete nasal obstruction — solution has nowhere to drain.
• Recent nasal or sinus surgery, unless your surgeon has advised it.
• Active ear infection or a perforated eardrum.
• Frequent ear problems, without discussing it first.