When performed using clean hands, a clean nasal irrigation device, and sterile water, nasal irrigation can be safe. Never use regular tap water to perform a sinus flush. Use only sterile water—distilled water, water that has been boiled and cooled, or water that has been filtered with a filter that can catch certain infectious organisms. And don’t use water that’s very hot or very cold.
For safety, breathe through your mouth while performing a sinus flush. And don’t perform the procedure if you have an ear infection, or if your nose is so clogged you can't breathe through it.