What Is Saline Solution?

Saline solution is a sterile, isotonic mixture of sodium chloride (NaCl) dissolved in purified water. In medical contexts, it is most commonly 0.9% NaCl, which matches the electrolyte concentration of human blood plasma and bodily fluids.

Composition

In chemistry, a solution is a homogeneous mixture of solute(s) in a solvent. Saline solution contains 0.85–0.9% sodium chloride by weight dissolved in 100 mL of purified water. This ratio keeps the solution isotonic, preventing cellular swelling or shrinkage when administered to patients.

How to Prepare a Homemade Saline Solution

For non‑sterile uses such as nasal irrigation or simple wound cleaning, you can make a basic saline solution at home:

• Use plain table salt (iodine‑free) to avoid potential irritation.
• Distilled or boiled water is preferred over tap water to reduce bacterial contamination.
• Mix 1 teaspoon of salt with 8 fluid ounces (1 cup) of water. This yields a 0.9% solution.
• If a sterile solution is required (e.g., for wound irrigation or eye care), boil the water, cool it to room temperature, and then add salt. Store the solution in a capped container to prevent bacterial growth.

Note: Commercial contact lens solutions contain buffering agents that maintain a pH suitable for the eye; the homemade recipe does not.

Saline for Intravenous Use

Normal saline (0.9% NaCl) is routinely administered via IV to correct dehydration, restore electrolytes, and provide a vehicle for other medications. It is especially useful in patients suffering from gastroenteritis, influenza, or other conditions that cause fluid loss.

Saline Injection in Clinical Settings

In hospitals, sterile saline is used to flush catheters, irrigate IV lines, and clean injection sites. It helps maintain sterility and prevents complications such as infection or thrombosis.

Medical Uses of Saline Solution

Beyond hydration, saline is versatile in clinical care:

• Wound Cleaning: Dilute the solution with water to gently remove debris and bacteria from minor injuries.
• Nasal Irrigation: Saline drops or neti pots relieve congestion, moisturize nasal passages, and reduce post‑nasal drip associated with colds or allergies.
• Eye Care: Saline drops soothe redness, dryness, and irritation, and are sometimes used to rinse foreign particles from the eye.
• Inhalation Therapy: Nebulized saline helps loosen mucus, making it easier to cough up and improving respiratory comfort.

Because saline is isotonic, it is generally safe for most patients, but always consult a healthcare professional before using it for medical purposes.