I checked with an experienced pharmacist on the correct ratio/proportions necessary to make a nasal saline 0.9% isotonic solution. (Isotonic means "same as body" saline levels.) Use 250 ml (1 cup) of distilled water (or purified by boiling 5 minutes then cooled). To this, add 1/3 or 2.25 grams of non-iodized canning or pickling salt.
Note: some sites say anywhere from 1/4 to 1 tsp. The correct proportion to achieve 0.9% is exactly 1/3 teaspoon.
Store in a sealed/covered container for up to 5 days. Use the solution as close to body temperature as possible for better absorption.
This is a page about homemade saline nasal spray. Saline spray is a great remedy for allergies or a stuffy nose. You can buy it at the store or make your own solution.
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For those of us who tend to use saline solution to calm allergic reactions, this recipe is a great money saver.