Saline works on your sinuses through several mechanisms at once: it physically flushes out irritants, thins sticky mucus, reduces swelling in nasal tissue, and helps the tiny hair-like structures in your nose do their job more effectively. It’s one of the few remedies recommended by major medical guidelines for both acute and chronic sinus problems, and it costs almost nothing to make at home.
How Saline Clears Mucus
Your nasal passages are lined with millions of microscopic hair-like projections called cilia. These cilia beat in coordinated waves, sweeping mucus (along with whatever it has trapped) toward the back of your throat, where you swallow it. When your sinuses are inflamed or infected, this system slows down. Mucus thickens, pools, and creates that familiar feeling of pressure and congestion.
Saline rinses restore this system in two ways. First, the liquid physically pushes mucus out, working as a simple mechanical flush. Forceful irrigation has been shown to be more effective than gentle rinsing, which supports the idea that physical force matters here. Second, saline softens and loosens thick, crusted secretions, making them less sticky and easier for your cilia to transport. Once the thick mucus is thinned out, ciliary beat frequency increases, and the whole clearance system speeds up.
Flushing Out Allergens, Viruses, and Pollutants
Your nasal mucus traps bacteria, viruses, pollen, dust, and air pollution particles before they can travel deeper into your respiratory system. The problem is that when these irritants accumulate faster than your body can clear them, they trigger inflammation. Saline irrigation reduces the concentration of all these substances in your nasal passages, which directly reduces the immune response they provoke.
High-volume, low-pressure rinses are the most efficient method for removing infectious agents, allergens, and inflammatory mediators. For people with allergies, this means physically washing away the pollen or dust that triggers their symptoms rather than just suppressing the body’s reaction with medication. During the COVID-19 pandemic, researchers also explored nasal irrigation as a way to reduce viral load. When saline rinses are started within 48 hours of cold symptoms appearing, they can shorten symptom duration, reduce the need for over-the-counter medications, and even lower household transmission of the virus.
How Saline Reduces Swelling
Not all saline solutions work the same way, and the difference comes down to salt concentration. Isotonic saline, with a salt concentration of 0.9%, matches the salt level of your body’s own fluids. It cleans mechanically by flushing out irritants and mucus without creating any osmotic pull on your tissues.
Hypertonic saline contains a higher concentration of salt, typically 3% or more. Because it’s saltier than your tissue fluid, it draws water out of swollen nasal membranes through osmosis. This shrinks inflamed tissue, opens your airways, and improves airflow. Hypertonic solutions also appear to suppress certain inflammatory signals, specifically reducing the release of compounds that contribute to postoperative swelling. The tradeoff is that hypertonic solutions are more likely to cause mild stinging or burning, especially in already-irritated tissue.
For everyday sinus congestion, isotonic saline is gentle and effective. Hypertonic saline offers stronger decongestion but can feel less comfortable.
What the Medical Guidelines Say
Saline irrigation carries a strong recommendation from clinical practice guidelines for chronic sinusitis, meaning the evidence is solid enough that doctors are expected to suggest it. For acute viral or bacterial sinus infections, it’s listed as an option for symptom relief alongside pain relievers and nasal steroid sprays. It’s also a standard part of care after sinus surgery, where it prevents crusting, promotes tissue healing, and flushes out clotted blood and debris from the surgical site.
After sinus surgery, hypertonic saline performs measurably better than isotonic. In a meta-analysis of seven studies covering 479 patients, hypertonic rinses reduced the presence of nasal crusting by 35% and decreased polyp-like tissue changes by 47% at two to three weeks, improving to 61% by one to two months. Patients also reported meaningful drops in symptom severity scores.
How to Make Saline at Home
Mix 3 teaspoons of non-iodized salt with 1 teaspoon of baking soda. This is your dry mix, and you can store it in a clean container. When you’re ready to rinse, dissolve 1 teaspoon of the mixture in 8 ounces of lukewarm water. The baking soda acts as a buffer, making the solution less irritating to your nasal lining.
The water you use matters more than the salt. Tap water can contain organisms, including a rare but deadly amoeba called Naegleria fowleri, that are harmless if swallowed but dangerous when introduced directly into nasal passages. The CDC recommends using only distilled or sterile water from the store, or tap water that has been boiled at a rolling boil for one minute (three minutes at elevations above 6,500 feet) and then cooled. If neither option is available, you can disinfect water with unscented household bleach: about 5 drops per quart for standard-concentration bleach, left to stand for at least 30 minutes before use.
Side Effects
Saline irrigation is remarkably well tolerated. The most commonly reported issues are minor: some nasal drainage after rinsing, mild initial discomfort while you get used to the sensation, and occasional stinging. Nosebleeds and significant irritation are rare. Hypertonic solutions cause more stinging than isotonic, so if you find the process uncomfortable, try lowering the salt concentration or making sure the water is comfortably warm, not hot or cold. Post-irrigation drainage, where saline trickles out of your nose for a few minutes after rinsing, is normal and not a sign of a problem.