Commercial eyewash is a sterile saline solution, typically 0.9% sodium chloride in purified water, designed to physically flush contaminants from the eye’s surface. Like all medical products, it carries an expiration date, which is the manufacturer’s safety guarantee. This date assures the product’s sterility and chemical integrity when stored correctly. Using eyewash past this date compromises its safety profile, potentially turning a first-aid measure into an additional risk for the delicate eye tissues.
The Primary Danger: Loss of Sterility
The expiration date signifies the end of the manufacturer’s guarantee that the solution is free of living microorganisms. Once this date passes, the solution cannot be guaranteed sterile, even if unopened.
This breakdown of the sterility barrier allows bacteria, fungi, or mold to proliferate inside the bottle. Microorganisms may enter through microscopic defects in the container material or cap seal that develop over time. Introducing a non-sterile solution directly onto the eye’s surface can lead to severe infections.
These infections may include conjunctivitis (pink eye) or keratitis, an inflammation of the cornea. Keratitis can rapidly progress, leading to corneal damage, pain, and potentially permanent vision loss. The risk of infection is elevated because the solution is used on an already irritated or injured eye, making it more vulnerable to pathogens.
Reduced Efficacy and Potential Irritation
Beyond the biological risk, expired eyewash faces chemical degradation that reduces its effectiveness and can cause irritation. Commercial eyewash is formulated to be isotonic (matching the salt concentration of natural tears) and pH-neutral, which is crucial for comfort and eye health. Buffering agents are often included to maintain this precise balance.
Over time, these chemical components can degrade or leach substances from the plastic container walls. This degradation can cause the solution’s pH to shift, making it either too acidic or too alkaline. Flushing the eye with a solution that is no longer pH-neutral can cause significant burning, stinging, and redness.
A chemically imbalanced solution can physically damage the surface of the eye. This can cause chemical irritation or potentially worsen the initial injury by damaging the corneal epithelium, leading to painful abrasions. Failure of an expired product to work effectively means the initial contaminant is not properly flushed, compounding the risk of long-term injury.
Safe Alternatives and Proper Disposal
If the only option available is an expired bottle, the safest course of action is to seek a reliable alternative. A fresh, unexpired bottle of sterile saline solution or contact lens solution can be used to flush the eye in a pinch. If neither is available, immediately use clean tap water, flushing the affected eye for a full 15 to 20 minutes, especially for chemical exposure. Promptly seeking medical attention remains the highest priority for any serious eye injury.
Proper Disposal
Disposing of expired eyewash is straightforward for most saline-based products. The liquid can generally be poured down the sink with running water, as it is a non-hazardous saline solution. The empty container, once rinsed, should be recycled or discarded according to local municipal guidelines for plastic waste. Always ensure the expired product is immediately replaced to maintain a current and safe first-aid stock.