Zaditen eye drops (Ketotifen)
How does it work?
Zaditen eye drops contain the active ingredient ketotifen, which is a type of medicine called an antihistamine.
Ketotifen works by preventing the actions of histamine, which is a substance produced by the body as part of its defence mechanisms. Histamine is stored in cells called mast cells, in almost all tissues of the body.
When the body reacts to a foreign substance (known as an allergen, eg flower pollen or pet fur), the mast cells stimulated by the allergen release their stores of histamine. The released histamine then binds to its receptors (H1 receptors), causing a chain reaction that results in allergic symptoms. It causes an increase in blood flow to the area of the allergy, and the release of other chemicals that add to the allergic response. All this results in the symptoms of an allergic reaction.
In hay fever, histamine causes eye symptoms such as inflammation, redness and itching by acting on H1 receptors in the eyes. Ketotifen blocks the H1 histamine receptors in the eyes, and thus stops these effects of histamine.
Ketotifen is used as eye drops so that it can act directly where it is needed.
What is it used for?
- Inflammation of the eyes due to hay fever (seasonal allergic conjunctivitis) in adults and children aged three years and older.
How do I use it?
- One drop should be put into each eye twice a day when needed to relieve symptoms. Follow this link for instructions on how to use your eye drops.
- For hay fever, if you know you are going to be exposed to the type of pollen that causes your symptoms, you can also use these eye drops before the exposure to help prevent the reaction in your eyes.
- You should not wear soft contact lenses while you are using these eye drops. This is because they contain a preservative called benzalkonium chloride, which can be absorbed by soft contact lenses and cause eye irritation. Contact lenses should be removed before putting in the drops and not put back in until at least 15 minutes after using the drops.
- This medicine is for use in the eyes only and must not be taken by mouth.
- When using the eye drops you should take care not to touch your eye or any surface with the dropper tip, to avoid contaminating the eye drops.
- These eye drops may cause your vision to blur temporarily after you have put the drops in your eyes. Do not drive or operate machinery until this has worn off.
- These eye drops should be discarded four weeks after the bottle is first opened. This is because after this time they could be contaminated with dirt or germs that could cause eye infections. Write the date of opening on the bottle so you know when to throw them away. Dispose of them carefully, preferably by returning them to your pharmacy.
Not to be used in
- Children under three years of age.
This medicine should not be used if you are allergic to any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.
If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.
Pregnancy and breastfeeding
Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.
- Only small amounts of ketotifen pass into the bloodstream after putting these eye drops in the eyes. This amount can be minimised by pressing on your tear ducts (the corner of the eyes closest to your nose) while putting in the drops and for a couple of minutes after.
- Although only small amounts of this medicine pass into the bloodstream, the safety of this medicine for use during pregnancy has not been established. It should therefore be used with caution during pregnancy, and only if the benefits to the mother outweigh any risks to the developing. Seek further medical advice from your doctor before using these eye drops if you are pregnant.
- The manufacturer states that these eye drops can be used by women who are breastfeeding. Seek further medical advice from your doctor.
Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.
Common (affect between 1 in 10 and 1 in 100 people)
- Pain and irritation of the eyes.
- Tiny breaks on the membrane covering the eyeball (punctate corneal epithelial erosion).
Uncommon (affect between 1 in 100 and 1 in 1000 people)
- Blurred vision after application.
- Dry eyes.
- Dislike of light (photophobia).
- Eyelid disorders.
- Skin reaction such as, eczema, rash, nettle rash.
- Hypersensitivity reactions.
- Dry mouth.
The side effects listed above may not include all of the side effects reported by the medicine's manufacturer.
For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.
How can this medicine affect other medicines?
If you are using more than one type of eye drop you should administer them at least five minutes apart, to prevent the second drop washing away the first. Use eye gels or ointments last.
This medicine has not been reported to affect any other medicines.
Other medicines containing the same active ingredient
There are no other eye preparations available in the UK that contain ketotifen as the active ingredient.
Zaditen tablets and elixir are available.