Artificial Tears Ingredients: What Each Part Does
Understand artificial-tear ingredients, from CMC and hyaluronic acid to oils, buffers and preservatives—and why “inactive” does not mean unimportant.
Most artificial tears contain water plus lubricating ingredients that help moisture stay on the eye’s surface. Some also contain oils to support the tear film, salts and buffers to balance the solution, and preservatives to limit microbial growth in the bottle. These formulas supplement tears; they do not recreate everything natural tears do. Ingredient review
The useful distinction is not simply “active” versus “inactive.” An ingredient listed as inactive can still affect hydration, thickness or tear-film stability. Here is how to read the names you may encounter.
The main lubricating ingredients
On U.S. OTC labels, the active ingredient’s purpose is often listed as lubricant. You may also see the term demulcent: an ingredient that protects and lubricates the eye’s surface to relieve dryness and irritation. Common names and roles include the following. U.S. formulation review
| Ingredient on the label | What it does |
|---|---|
| Carboxymethylcellulose sodium (CMC) | A cellulose-derived polymer that helps the drop cling to the eye’s surface and increases its thickness, or viscosity. |
| Hypromellose, also called hydroxypropyl methylcellulose (HPMC) | Another cellulose-derived polymer that moistens and lubricates the surface and helps the drop remain there. |
| Polyethylene glycol 400 (PEG 400) | A lubricating ingredient used alone or in combinations, including with propylene glycol. |
| Propylene glycol and glycerin | Lubricants that also act as humectants—ingredients that help retain moisture. |
| Polyvinyl alcohol, povidone and dextran 70 | Other lubricating polymers used in artificial tears, sometimes in combination formulas. |
These roles are described in the formulation review. The table is an ingredient glossary, not a ranking: the complete formula matters, not just the first name listed.
For example, the U.S. label for Systane Ultra PF single-use vials, updated December 2023, lists PEG 400 0.4% and propylene glycol 0.3% as active lubricants. It also lists several inactive ingredients that help shape the solution. Those percentages describe concentration, not a score of how well the drop will work for you. DailyMed label
Hydrating polymers and oils may be “inactive”
Hyaluronic acid or sodium hyaluronate binds water and aids lubrication and retention on the eye. Hydroxypropyl guar and carbomer help thicken or form a gel-like solution, increasing the time it stays on the surface. These ingredients can appear in the inactive list of U.S. products; labeling conventions differ between countries. Ingredient review · U.S. formulation review
Thickness has a trade-off: thicker lubricants tend to last longer, but can cause more or longer-lasting temporary blur. American Academy of Ophthalmology
Castor oil, mineral oil and flaxseed oil—also called linseed oil—are lipid ingredients. Their role is to support the oily part of the tear film and help reduce evaporation. They are not present in every artificial tear. U.S. formulation review
A concrete example is Refresh Optive Mega-3: its U.S. label, updated June 2022, lists CMC, glycerin and polysorbate 80 as active lubricants, while castor oil and flaxseed oil appear under inactive ingredients. That placement does not make the oils irrelevant to the formula. DailyMed label
What the other ingredients do
The rest of the list usually serves several distinct purposes:
- Electrolytes, such as sodium chloride, potassium chloride, calcium chloride and magnesium chloride, help establish the solution’s salt balance and reproduce aspects of healthy tears. Ingredient review
- Buffers and pH adjusters help control acidity or alkalinity. Boric acid can act as a buffer. Hydrochloric acid and sodium hydroxide may sound alarming in isolation, but the Systane Ultra PF label specifically identifies their role as adjusting pH. Ingredient review · Systane label
- Osmoprotectants, such as erythritol, levocarnitine (L-carnitine) and trehalose, are included to help cells withstand stress from overly concentrated tears. This describes their intended role, not a guarantee that a formula containing them will outperform another drop. Ingredient review
- Emulsifiers or surfactants help keep oil droplets dispersed in water. Polysorbate 80 can serve this function as well as being listed as an active lubricant in some formulas. U.S. formulation review
Preservatives are a separate ingredient category
Preservatives help prevent microbial growth in multidose bottles. Names include benzalkonium chloride (BAK), polyquaternium-1, sodium perborate and stabilized oxychloro complex, often called Purite. They are not the lubricants, and they differ in their effects on the eye’s surface. BAK is particularly associated with irritation and surface damage with repeated, prolonged exposure. Preservative review
Preservative-free does not mean free of all inactive ingredients. Such drops can still contain polymers, salts, buffers or oils, as the labels above illustrate. For packaging and use considerations, see our guide to preservative-free artificial tears.
Read the exact package rather than assuming every product in a brand has the same formula. Ingredient names alone also do not establish contact-lens compatibility: the packaging must explicitly allow use while lenses are in. Artificial tears provide symptom relief, but persistent discomfort may need assessment of the underlying cause. Seek same-day eye care for sudden vision changes, eye pain or light sensitivity. American Academy of Ophthalmology