How long does one bottle of latanoprost last?

October 9, 2025 •

4 min read

For patients using latanoprost once daily, a standard 2.5 mL bottle contains approximately 50-80 drops. This means that while a bottle may hold enough medication for up to 50 days if treating one eye, it must be discarded a maximum of 6 weeks after opening to ensure safety and effectiveness.

Quick Summary

The duration of a latanoprost bottle is determined by both the volume of drops and a strict expiration timeline after opening. A typical 2.5 mL bottle provides enough medication for 25-50 days, depending on whether one or both eyes are treated. However, most bottles must be thrown away just 4-6 weeks after being opened, regardless of the remaining contents.

Key Points

Standard Duration: A typical 2.5 mL bottle of latanoprost contains enough liquid for approximately 50-80 drops, which translates to about 25-50 days of use depending on whether one or both eyes are treated.
Critical Expiration Rule: Once opened, the bottle must be discarded after 4-6 weeks (28-42 days), regardless of how much medication is left inside, to prevent contamination.
Storage Conditions: Most unopened latanoprost bottles require refrigeration, but can be stored at room temperature for the designated 4-6 week period after opening.
Once-Daily Dose: Latanoprost should only be taken once daily in the evening, as more frequent use can lessen its intraocular pressure-lowering effect.
Technique and Waste: Poor administration technique can cause drops to be wasted, potentially making the bottle run out of medicine faster. However, the 4-6 week discard rule is still the priority.
Mark Your Calendar: Writing the date of opening on the bottle is a simple but effective way to track when to discard the medication.
Brand Variations: Some products, like Iyuzeh or Xelpros, have different storage and discard instructions, so always check the specific product information.

Standard Bottle Size and Estimated Use

Latanoprost is a medication prescribed to treat conditions like open-angle glaucoma and ocular hypertension by lowering intraocular pressure. It is almost always administered as a single drop, once daily, into the affected eye(s). Most multidose bottles contain 2.5 mL of solution. The number of drops dispensed can vary based on the specific dropper, but estimates typically fall within a predictable range. Some bottles may contain an overage to account for administration mistakes.

For a standard 2.5 mL bottle and a once-daily dosage:

For one eye: With approximately 50-80 drops per bottle, the medication would last roughly 50 to 80 days.
For both eyes: If you need to treat both eyes, the bottle would contain enough for approximately 25 to 40 days of use.

The Critical Expiration Rule: Discard After 6 Weeks

While a bottle may contain enough liquid for more than a month, a key factor that determines its lifespan is the expiration date after opening. Most latanoprost products contain a preservative, and once the bottle is exposed to air, its sterility cannot be guaranteed for an extended period. For many brands, this means:

Discard after 6 weeks (42 days): For many generic latanoprost solutions, as well as the brand Xalatan, the bottle must be thrown away 6 weeks after opening, even if there is still liquid inside.
Discard after 4 weeks (28 days): The NHS and some other sources specify a 4-week discard period for opened bottles.

For most patients, this post-opening expiration date will be the limiting factor for how long a bottle lasts, overriding the theoretical calculation based on the number of drops. To remember the date, it is wise to write the opening date directly on the bottle's label or box.

Comparison of Latanoprost Bottle Duration


Factor	One Eye (approx. 50-80 doses)	Both Eyes (approx. 25-40 doses)	Conclusion
Usage Period (by dose)	Up to 80 days	Up to 40 days	Use-by date is almost always shorter than dose-based duration when treating one eye.
Safety Period (after opening)	4-6 weeks (28-42 days)	4-6 weeks (28-42 days)	Most common lifespan: For a once-daily dose, the bottle will expire due to safety concerns before it runs out of drops.
Improper Storage	Decreases stability and effectiveness.	Decreases stability and effectiveness.	Can reduce the effective lifespan to less than 4-6 weeks.
Missed Doses	Extends theoretical drop-based usage, but does not extend safety period.	Extends theoretical drop-based usage, but does not extend safety period.	Should not be used to justify keeping a bottle longer than 4-6 weeks after opening.

Factors Affecting Your Bottle's Lifespan

Several factors can influence how long a bottle of latanoprost truly lasts, including storage, administration, and brand-specific instructions.

Proper Storage: Unopened bottles of most latanoprost generics and brand-name Xalatan must be stored in the refrigerator between 2° and 8°C (36° to 46°F) to maintain potency. Once opened, they can be kept at room temperature for the designated 4-6 weeks. Some newer formulations, such as Xelpros, do not require refrigeration at all. Exposure to extreme temperatures or light can degrade the medication, rendering it less effective.
Administration Technique: Applying the drops correctly helps minimize waste. Many eye drop applicators deliver a larger drop than needed, with a significant portion often lost through overflow. Closing the eye gently and applying pressure to the inner corner for 1-2 minutes can maximize absorption and reduce waste. Wasting drops will naturally decrease the bottle's total usable lifespan.
Brand Variations: Some formulations, like Iyuzeh, have slightly different recommendations. Iyuzeh, for example, specifies a 30-day discard period after opening. Always consult the specific instructions for your prescription.

What to Do When the Bottle is Used Up (or Expired)

The most important rule is to adhere to the discard date. Using contaminated or degraded drops can put your eye health at risk, potentially leading to infection or reduced therapeutic effect.

If you find your bottle is consistently running out before the 4-6 week mark, discuss your technique with your doctor or pharmacist. If you have been treating both eyes, your doctor may prescribe a larger bottle to better match the usage timeline. If you run out early due to missed doses, do not double up on your next dose, as this can be counterproductive to lowering intraocular pressure. Instead, simply continue with your regular schedule.

Conclusion

For most latanoprost users, the practical lifespan of a bottle is dictated by the 4-6 week expiration period after opening, not the volume of medication inside. It is crucial to mark the opening date and discard the bottle promptly to ensure the eye drops remain sterile and effective. Proper storage is also essential to maintain potency throughout the usable period. By following these guidelines, patients can ensure they are using their medication safely and effectively to manage their condition. For more detailed pharmacological information, resources like the StatPearls summary from the National Center for Biotechnology Information (NCBI) are available(https://www.ncbi.nlm.nih.gov/books/NBK540978/).

Frequently Asked Questions

You must discard the bottle after 6 weeks to ensure the medication remains sterile and effective. Over time, the preservative can become less effective, increasing the risk of contamination and eye infection.

Using the drops after the 6-week mark increases the risk of eye infection. The medication may also lose potency, becoming less effective at lowering your intraocular pressure.

A standard 2.5 mL bottle of latanoprost generally contains between 50 and 80 drops, depending on the specific product and dropper.

Unopened bottles of most latanoprost products, including Xalatan, must be kept refrigerated. Once opened, they can be stored at room temperature for up to 6 weeks, but should be discarded after that time.

If you miss a dose, simply continue with your next scheduled dose in the evening. Do not double up on doses, as taking more than once a day can reduce the medication's effectiveness.

No, latanoprost should not be used more than once daily. More frequent use can actually cause the medication to be less effective or have a paradoxical effect, causing an increase in eye pressure.

The intraocular pressure-lowering effect of latanoprost begins approximately 3 to 4 hours after administration, with the maximum effect reached within 8 to 12 hours.