Using rewetting drops correctly comes down to clean hands, proper head positioning, and getting the drop into the right spot without contaminating the bottle. It sounds simple, but small technique mistakes can reduce effectiveness or even introduce bacteria to your eyes. Here’s how to do it right, along with the details that make a real difference.
Step-by-Step Application
Start by washing your hands thoroughly with soap and water. This matters more than most people realize. A 30-year review of research on eye drop contamination found that bacteria from human skin are the most common microorganisms cultured from dropper tips, and contaminated bottles are a leading cause of preventable eye injuries including corneal damage.
Once your hands are clean, follow this sequence:
- Tilt your head back and look up toward the ceiling.
- Pull down your lower eyelid with one hand, creating a small pocket between your eyelid and your eyeball.
- Hold the bottle upside down with your other hand, positioning the tip just above that pocket. Don’t let the tip touch your eye, eyelid, or fingers.
- Squeeze one drop into the pocket. One drop is enough per eye. The pocket can only hold about one drop anyway, so extra liquid just rolls down your face.
- Close your eye gently and press a finger lightly against the inner corner of your eye (where the tear duct sits) for at least one minute. This prevents the drop from draining into your nasal passage, which is where most of it goes if you skip this step.
That last step, pressing the tear duct, is the one most people skip. It keeps the moisture on your eye’s surface longer, which is the entire point.
How Often You Can Use Them
If your drops contain preservatives (most multi-use bottles do), limit yourself to four times a day. The American Academy of Ophthalmology recommends this threshold because preservatives like benzalkonium chloride can accumulate on the eye’s surface and cause irritation, inflammation, or damage to the cornea with repeated exposure.
If you need drops more than four times daily, switch to preservative-free formulations. These typically come in single-use vials and are safe for frequent use, even hourly in severe cases. They contain no chemicals that build up on your eye over time, making them the better choice for anyone with chronic dryness, digital eye strain from long screen sessions, or ongoing sensitivity.
Using Drops With Contact Lenses
Not all rewetting drops are safe to use while wearing contacts. Benzalkonium chloride, a common preservative in standard eye drops, is easily absorbed by contact lens material and then slowly released onto your eye. This can cause significant irritation and has well-documented toxicity to corneal cells. If you wear soft contacts, look specifically for drops labeled as contact lens compatible or preservative-free.
Some preservatives used in contact lens care products can also cause problems. Research has linked certain disinfecting chemicals to corneal staining, particularly with silicone hydrogel lenses. The safest approach is to use only drops specifically designed for rewetting contact lenses, or to remove your lenses before applying standard lubricating drops and wait before reinserting them.
Spacing Drops With Other Eye Medications
If you’re using rewetting drops alongside prescription eye drops (for glaucoma, allergies, or post-surgical care), wait at least three minutes between different drops. Walter Reed’s post-LASIK protocol recommends applying lubricating drops first, then waiting before using medicated drops. This prevents the first drop from washing out the second and gives each medication time to absorb.
The order generally matters too. Thinner, watery drops go in first. Thicker, gel-like drops or ointments go last, since they coat the surface and would block anything applied afterward.
Preservative-Free Drops: When They Matter
Preservative-free drops are worth the extra cost in several specific situations: after eye surgery like LASIK or cataract procedures, if you have severe or chronic dry eye, if you use multiple eye medications daily, or if you have conditions like Sjögren’s syndrome or ocular rosacea. They’re also the better option for anyone who has noticed burning or stinging from standard preserved drops.
After LASIK specifically, the lubrication schedule is intensive. Typical protocols call for one drop every hour during waking hours for the first week, then gradually tapering: about eight times a day for the first month, six times daily through the third month, four times daily through the sixth month, and twice daily out to a full year. Preservative-free drops are essential at this frequency because preserved drops would cause cumulative toxicity at those application rates.
Long-term users report noticeably better comfort after switching from preserved to preservative-free formulations. Over time, avoiding preservatives leads to better tear film stability and improved corneal health.
Choosing the Right Type
Rewetting drops come in different formulations designed for different problems. If your eyes feel dry because tears evaporate too quickly (common with windy environments, heating, or air conditioning), look for drops with lipid-based or oil-based ingredients. These thicken your tear film and slow evaporation.
If your eyes simply don’t produce enough tears, thinner drops labeled “hypotonic” or “hypoosmolar” work better. These add volume to your natural tear layer without making your vision feel greasy or blurry.
Storage and Shelf Life
Store multi-use bottles at room temperature, generally between 2°C and 25°C (about 36°F to 77°F) in the United States. Refrigerating eye drops might seem logical, but some formulations shouldn’t be stored cold. Low temperatures can alter the consistency of certain drops, particularly suspensions, and make them less effective.
Single-use preservative-free vials should be discarded immediately after use. They contain no preservatives to prevent bacterial growth, so reusing an opened vial risks contamination. Multi-use bottles typically have an expiration date printed on the packaging, but once opened, most should be used within 28 to 30 days regardless of the printed date. Check the label for your specific product.
Common Mistakes to Avoid
The biggest mistake is touching the dropper tip to your eye, eyelid, or lashes. Research spanning three decades consistently shows that this transfers bacteria from your skin flora onto the bottle tip, which then contaminates the remaining contents. Those bacteria can cause corneal injuries and bacterial infections of the eye’s surface.
Other common errors include using too many drops at once (the excess just spills out and wastes product), blinking rapidly after application (which pumps the drop out through your tear duct before it absorbs), and using preserved drops too frequently. If you find yourself reaching for drops six or eight times a day from a preserved bottle, that’s a sign to switch formulations rather than push through the discomfort.