How Many Drops Are There In A 5 mL Bottle?

This is a question commonly asked by patients especially the users of glaucoma eye drops since they are supposed to take the treatment for a long time.

How many drops a bottle will dispense depends on the viscosity of the drug and the size of the hole in the eye dropper. It is generally accepted that the drugs which have the viscosity similar to that of water will have about 20 drops in one milliliter which means we will have 100 drops in 5 mL.

To confirm and test, I took a few bottles of 5 mL eye drops and counted how many drops they provided individually. They ranged from 115 drops to 130 drops per 5 mL bottle. This does not mean that all eye drops of 5 mL capacity have 115 to 130 drops but we can safely assume that most of the 5 mL eye drop bottles have much more than 100 drops.

There are two important considerations here:
1. Many eye drops are available in volumes sufficient to last about one month. Depending on the dosage, they are available in 2.5 mL, 3 mL, 5 mL and 10 mL mostly.
2. Only one drop is enough to be instilled into the eye at a time and delivers the required dose. Any amount more than that will flow out of the eye because the conjunctival sac (the space between the eyelids and the eyeball) does not have room for more than one drop generally.

In the above context, let’s take the example of a few drugs. Timolol, for instance, is an anti-glaucoma drug used twice a day. For both eyes (glaucoma is mostly bilateral), it will be 4 drops a day and 120 (4 x 30) drops a month. So if you get 120 drops from the 5 mL bottle of Timolol, it should be sufficient for one month. Timolol eye drop is available mostly in 5 mL capacity.

Latanoprost/Xalatan eye drop is used once a day only. For both eyes, it will be 2 drops a day and 60 drops a month. It is mostly available in 2.5 mL capacity.

Ketotifen eye drop is used for allergy twice a day. For both eyes, 4 drops will be used in a day and 120 drops in a month. Ketotifen is available in 5 mL and 10 mL volumes (for one month and two months respectively).

The above analysis suggests that there are about 120 drops in a 5 mL bottle. This is fairly supported by my tiny experiment with some eye drop bottles. This obviously is not applicable to eye drops in suspension and gel forms.

6 thoughts on “How Many Drops Are There In A 5 mL Bottle?”

  1. Re Timolol The last three months I have not been able to get a 5ml bottle to last 30 days (I have used them for approx 3 yrs). Either there are not enough drops n the bottles or (my suspicion) the dispensed drops are now bigger – different supplier now these last three months.

    Reply
    • In a fresh bottle there is no hole in the nozzle. The hole is created by rotating the cap which has a spike inside. If you rotate the cap excessively, the hole will be larger and there will be delivery of larger drops. Next time, try to rotate the cap just enough to make the hole. If the size of drops is appropriate, your bottle should last for a month.

      Reply
      • I use Timolol 0.5% and the bottles do not have a “spike inside” the cap. The cap is rotated to remove it and replace it. The end-user has no control of the hole size.

        Reply
  2. I am having trouble getting enough drops out of a 5mL bottle of Prednisolone acetate. I’ve never had this trouble with any other drops I use for glaucoma. Scares me that I’ll be about a week short.

    Reply
  3. I had cataract surgery and my right eyes pressure was very high so my physician prescribed Alphagan P eye drops. In less than two weeks my bottle was almost empty and pressure was still high so doctor told me to continue 1 drop 3xs daily. Doctor had to prescribe a new bottle bjt at first my insurance said no because the drops should have lasted at least a month but they grudgingly decided to override. I got another bottle. My doctor told me to continuen for 3 more weeks. Now into my 3rd week since getting the 2nd bottle I am almost out of drops and doubt I will have enough drops to last 8 mkre days. This is a Rip Off. I am very careful and have jsed one drop every single time.

    Reply

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