Saline solution is a simple mixture of sterile water and sodium chloride, which is common table salt. The general safety profile for accidental ingestion depends almost entirely on the product’s concentration and whether it contains additional chemicals. For most medical-grade saline solutions, which are often used for rinsing wounds or nasal irrigation, swallowing a small amount is usually benign. However, many consumer products labeled as “saline,” such as contact lens solutions or medicated nasal sprays, contain powerful additives that present a genuine risk if swallowed.
The Chemical Composition of Pure Saline
Pure saline, medically known as Normal Saline, is defined by a precise chemical ratio of 0.9% sodium chloride dissolved in sterile water. This specific concentration means there are 9 grams of salt per liter of solution, which creates an environment that is approximately isotonic with human blood and body fluids. Isotonicity is the reason this solution is so widely used, as it minimizes the osmotic shift of water into or out of the body’s cells.
When a small amount of this solution is accidentally swallowed, the body’s natural homeostatic mechanisms easily manage the modest salt load. The kidneys play a primary role in regulating blood sodium levels and will work to excrete the excess sodium and chloride ions via urine. For a healthy individual, the ingested volume is typically too small to cause any significant systemic imbalance. Larger volumes, however, can strain the kidneys as they work harder to process the sudden increase in sodium.
The Hidden Dangers of Saline Product Additives
The primary risk from ingesting a product labeled “saline” comes from the non-salt ingredients present in many commercial formulations. Products like contact lens solutions and decongestant nasal sprays contain potent chemicals to disinfect or reduce swelling. These additives are safe for external or topical use but can be highly toxic if they enter the digestive system.
A common preservative in multipurpose solutions is benzalkonium chloride (BAC), a cationic detergent added to kill bacteria. If swallowed, even in the low concentrations found in these products, BAC can act as a local corrosive agent, irritating the mucous membranes of the mouth, throat, and gastrointestinal tract.
Certain eye drops and medicated nasal sprays contain active ingredients like tetrahydrozoline, oxymetazoline, or naphazoline, which are powerful vasoconstrictors used to reduce redness and congestion. These ingredients are especially dangerous if swallowed by children. Even a small amount can lead to severe systemic poisoning. This toxicity is not related to the saline component but rather to the drug’s effect on the central nervous system and cardiovascular system.
Recognizing Symptoms and Knowing When to Act
Symptoms following accidental ingestion can range from mild discomfort to a life-threatening medical emergency, depending on the type and amount of solution swallowed. Mild exposure typically results in gastrointestinal irritation. Expected symptoms include nausea, vomiting, or diarrhea as the body attempts to expel the irritating chemicals.
More serious symptoms arise from the ingestion of larger quantities or solutions containing toxic vasoconstrictors or high concentrations of benzalkonium chloride. These severe signs require immediate medical attention and can include respiratory distress, significant changes in heart rate, or blood pressure fluctuations. Neurological changes, such as profound sedation, lethargy, confusion, or coma, are clear indicators of a systemic poisoning event.
If a small, unmedicated saline solution was swallowed, rinsing the mouth and drinking a small amount of water to dilute the salt is appropriate. However, if the ingested product was a contact lens solution, a medicated eye or nasal drop, or if the individual is experiencing severe symptoms like vomiting, drowsiness, or difficulty breathing, call Poison Control immediately. Swift action is crucial for a positive outcome.