Sterile water in eye drops

Sterile water in eye drops is purified water that has been made free of living microorganisms, used as the base that carries the other ingredients. In Quell it’s listed as an inactive ingredient, “Sterile Water.” It isn’t there to add moisture on its own; it’s the liquid the formula is made in. Federal rules require any product for the eye to be sterile, and a sterile base is part of meeting that.

What is sterile water in eye drops?

Most eye drops are mostly liquid, and that liquid has to come from somewhere. In many products, Quell included, it’s water. The word “sterile” is the important part: it means the water contains no living bacteria, fungi or other microorganisms when it goes into the product. Ordinary drinking water, even clean tap or bottled water, isn’t held to that standard.

Think of it as the vehicle. The active ingredients do the work the label describes, and the water is the medium that holds them, so each drop carries the formula to the eye in a form you can apply from a bottle.

Where it appears on Quell’s label

Quell’s Drug Facts panel lists three active ingredients, Glycerol (1.0%), Polysorbate 80 (1.0%) and Light Mineral Oil (0.5%), and 10 inactive ones: Caprylyl Glycol, Dead Sea Salt (Sodium Chloride), Emu Oil, Glyceryl Laurate, Glyceryl Undecylenate, Manuka Honey, Polaxamer 188, Sterile Water, Terminalia Chubula and Tromethamine. Sterile Water is one of the inactive ingredients.

Its place in the list says nothing about how much is in the bottle. FDA’s labeling rule for over-the-counter drugs, 21 CFR 201.66, requires the inactive ingredients of an OTC drug that isn’t also a cosmetic to be listed in alphabetical order. That puts Sterile Water near the end simply because of the letter S. The inactive ingredients on an eye drop label explains how that section works.

Why is sterile water an inactive ingredient?

On a Drug Facts label, the active ingredients are the ones with a stated purpose. Quell lists Glycerol (1.0%) and Polysorbate 80 (1.0%) as lubricants and Light Mineral Oil (0.5%) as an emollient. Everything else in the formula goes under inactive ingredients, which covers bases, natural ingredients, and the components that hold a formula together and keep it stable. Water belongs there because it carries the actives rather than being one.

Inactive doesn’t mean unimportant. Without a base, there would be no drop to apply. It just means the water isn’t what the label’s Uses statement rests on.

What federal rules say about sterility

FDA’s regulation on ophthalmic preparations, 21 CFR 200.50, opens by saying informed medical opinion agrees that all preparations for use in the eye, including eye-cleansing products, should be sterile. It records that in a statement of policy issued on September 1, 1964, FDA ruled that liquid eye preparations that aren’t sterile may be regarded as adulterated, and the regulation extends that ruling to all ophthalmic preparations regulated as drugs.

That requirement covers the whole finished product, not one ingredient. A sterile water base is a natural starting point, but the regulation is about what ends up in the sealed bottle. Our guide Are eye drops sterile? covers what happens once you open it and how to keep the bottle clean.

Can I use sterile water as eye drops?

Not as a substitute for an eye drop. Sterile water sold on its own, for example for mixing or rinsing in medical settings, isn’t labeled as an over-the-counter eye drop for dryness, and its label won’t give you eye-drop directions or warnings. Tap, bottled and distilled water aren’t sold as sterile eye products at all. If you’re thinking of putting anything in your eye that isn’t labeled for it, ask a pharmacist or eye doctor first.

Emergencies are different. If a chemical splashes into your eye, follow the instructions on the product, your workplace’s emergency procedure or poison control, which often means flushing the eye right away, and get medical help. That isn’t the same as choosing a daily drop.

Is sterile water good for dry eyes?

Water alone isn’t what keeps the eye comfortable. The tear film has three layers, oil, water and mucus, and the oil layer on top slows the water beneath it from evaporating. When that layer is thin or the air is dry, water evaporates quickly, which is why plain water wouldn’t stay put for long. The tear film’s water layer, explained goes into that layer in detail.

Quell is designed to reinforce the tear film’s oil layer to help reduce moisture loss. That design comes from the formula as a whole, not from the water in it. The sterile water simply carries the actives and the other inactive ingredients.

Why water-based drops can look milky

Quell isn’t clear, and that surprises some people who expect water-based drops to look like water. The label describes it this way: Product appears as a milky brown solution. The oil-based ingredients in the formula give it that look. In plain terms: The eye drops have a naturally milky-brown appearance. This is normal and does not indicate a problem with the product. What the label does say to watch for is a change: If this product changes color.

Using a sterile product well

A product that starts out sterile stays as clean as you keep it. The label’s handling line reads: Do not touch tip of bottle to any surface to avoid contamination. Follow the directions, Apply 1 drop 3 times per day in each eye, and store it as the label says: Store between 15° to 30°C (59° to 86°F). Read the caution before your first use: Caution should be used in those with egg or bird allergies — For use in the eyes only. The full panel is on our Drug Facts page.

If your eyes feel worse after using any drop, stop. The label says: Stop use and ask a doctor if you feel eye pain or changes in your vision, if irritation or redness continues, or if the condition worsens or persists for 72 hours.