Hypertonic Saline: Uses, Forms, and Safety

Hypertonic saline is simply salt water with more salt than normal blood. That extra salt pulls water out of swollen tissues, thins thick mucus, and raises blood sodium when it’s dangerously low. Clinicians use different concentrations for very different problems — inhaled solutions for lung clearance, and concentrated IV solutions for brain swelling or severe hyponatremia.

Common forms and when they’re used

Concentration matters. Neat examples: 3% saline is the most common hypertonic solution used both as a nebulized mist and as an IV fluid. Nebulized 3% (sometimes 3–7%) helps people with cystic fibrosis, bronchiectasis, or severe cough by loosening sticky mucus so it’s easier to clear. For infants with bronchiolitis some hospitals use nebulized 3% to shorten symptoms, though practice varies.

IV 3% saline is used when sodium is dangerously low and the patient shows symptoms like seizures, severe confusion, or coma. Much stronger solutions — 23.4% saline — are reserved for emergency reduction of raised intracranial pressure (brain swelling) and are given through a central line because they’re very concentrated and can irritate smaller veins.

Safety tips you should know

Hypertonic saline works fast, so the biggest risk is overdoing it. Rapid correction of low sodium can damage the brain (central pontine myelinolysis). Hospitals monitor sodium closely during treatment — usually every 2–4 hours while correcting acute, severe hyponatremia. Many protocols aim to limit correction to about 8–10 mmol/L in 24 hours, but your care team will set a target based on your situation.

For inhaled use, hypertonic saline can trigger bronchospasm in people with reactive airways. If you wheeze easily, providers often give a bronchodilator (like salbutamol) first or test tolerance with a small dose. Use sterile, preservative-free saline for nebulizers; do not use homemade or non-sterile solutions for inhalation.

People with heart failure, advanced kidney disease, or uncontrolled high blood pressure need careful evaluation before receiving IV hypertonic saline. Extra salt can raise blood volume and strain the heart and kidneys. For very concentrated solutions (like 23.4%), a central venous line is standard to avoid vein damage.

Practical things to remember: if you’re prescribed nebulized hypertonic saline, follow device instructions and report increased coughing or wheeze. If you or a loved one receives IV hypertonic saline in hospital, expect frequent blood tests and clear rules about how fast sodium should change. Always ask the care team why they chose a particular concentration and what side effects to watch for.

Hypertonic saline is a simple tool with powerful effects. Used correctly, it can relieve dangerous swelling and stubborn mucus. Used carelessly, it can cause real harm. Talk to your clinician about benefits and risks for your specific condition.