In the U.S.—

• Antihistamine, H₁– receptor, ophthalmic
• mast cell stabilizer, ophthalmic
• antiallergic, ophthalmic

Ketotifen (kee-toe-TYE-fen ) ophthalmic (eye) solution is used to temporarily prevent itching of the eye caused by a condition known as allergic conjunctivitis. It works by acting on certain cells, called mast cells, to prevent them from releasing substances that cause the allergic reaction.

This medicine is available only with your doctor's prescription, in the following dosage forms:

Ophthalmic
• Ophthalmic solution (eye drops) (U.S.)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For ketotifen, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to ketotifen. Also tell your health care professional if you are allergic to any other substances, such as preservatives.

Pregnancy—Ketotifen has not been studied in pregnant women. However, studies in animals have shown that ketotifen, when given in very high doses to some types of animals, causes birth defects. Before using this medicine, make sure your doctor knows if you are pregnant or if you may become pregnant.

Breast-feeding—It is not known whether ketotifen passes into human breast milk. However, it does pass into the milk of animals with nursing young. Mothers who are taking this medicine and who wish to breast-feed should discuss this with their doctor.

Children— Studies on this medicine have been done only in adult patients, and there is no specific information comparing use of ketotifen in children younger than 3 years of age with use in other age groups.

Older adults—Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing use of ophthalmic ketotifen in the elderly with use in other age groups.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your health care professional if you are taking or using any other prescription or nonprescription (over-the-counter [OTC]) medicine.

Do not wear contact lenses if your eyes are red . Also, do not use this medicine to treat irritation related to contact lens use. If you wear contact lenses: Take out your contact lenses before using ketotifen eye drops. Wait at least 10 minutes after putting the eye drops in before putting the contact lenses back in.

To use the eye drops:

• First, wash your hands. Tilt the head back and, pressing your finger gently on the skin just beneath the lower eyelid, pull the lower eyelid away from the eye to make a space. Drop the medicine into this space. Let go of the eyelid and gently close the eyes. Do not blink. Keep the eyes closed for 1 to 2 minutes to allow the medicine to be absorbed by the eye.
• If you think you did not get the drop of medicine into your eye properly, use another drop.
• To keep the medicine as germ-free as possible, do not touch the applicator tip to any surface (including the eye). Also, keep the container tightly closed.

Dosing—

The dose of ketotifen will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of ophthalmic ketotifen. If your dose is different, do not change it unless your doctor tells you to do so.

• For ophthalmic dosage form (eye drops):
  • For prevention of itching of the eye due to allergic conjunctivitis (eye allergy):
    • Adults and children 3 years of age and older—Use one drop in each affected eye every 8 to 12 hours.
    • Children up to 3 years of age—Use and dose must be determined by your doctor.

Missed dose—

If you miss a dose of this medicine, use it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Keep the medicine from freezing.
• Do not keep outdated medicine or medicine no longer needed. Ask your health care professional how you should dispose of any medicine you do not use. Be sure that any discarded medicine is out of the reach of children.

If your symptoms do not improve or if your condition becomes worse, check with your doctor.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• More common
  • Eye redness and swelling 
  
  

• Less common
  • Eye discharge;  eye discomfort;  eye pain;  hives;  increased itching of eyes;  rash.  
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • Headaches;  stuffy or runny nose 
  
  

• Less common
  • Burning or stinging of eyes;  dry eyes ;  eyelid disorder;  eye sensitivity to light;  fever, tiredness, achiness, and sore throat ;  increase in size of pupils;  sore throat;  tearing. 
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.