• Ketotifen is used to help prevent allergic conditions.
  • The most common side-effect is drowsiness.
  • Ketotifen may affect your ability to drive and use machines. Do not drive if you are not fully alert or able to see clearly.

About ketotifen

Type of medicine Antihistamine
Used for Allergic conditions
Also called Zaditen®
Available as Tablets, oral liquid and eye drops

Exposure to substances such as pollen, pet fur, house dust, or insect bites can cause the body to produce a chemical called histamine. The release of histamine causes allergic symptoms which can include sneezing, itchy or watery eyes, a runny or blocked nose, and itchy skin reactions and rashes.

Ketotifen stops the effects of histamine and helps to relieve these symptoms.

Before taking or using ketotifen

Before taking or using ketotifen make sure your doctor or pharmacist knows:

  • If you are pregnant, trying for a baby or breast-feeding.
  • If you have glaucoma.
  • If you have prostate problems, or have been experiencing difficulty passing urine.
  • If you know you have a blockage in your small intestines.
  • If you have liver problems.
  • If you have epilepsy.
  • If you have been advised to use ketotifen eye drops and you wear soft contact lenses.
  • If you are taking other medicines, including those available to buy without a prescription, herbal and complementary medicines.
  • If you have ever had an allergic reaction to an antihistamine or to any other medicine.

How to take or use ketotifen

  • Read the manufacturer's printed information leaflet from inside the pack before starting this treatment.
  • Follow the directions you have been given by your doctor. Usually ketotifen is taken (or applied) twice each day.
  • It is best to have your doses of ketotifen at the same times each day in order to avoid missing any doses.
  • If you do forget a dose, have it as soon as you remember unless it is nearly time for your next dose, in which case leave out the missed dose. Do not 'double up' to make up for forgetting a dose.
  • If you have been given ketotifen tablets or oral liquid, take your doses with food, or soon afterwards.

How to use ketotifen eye drops:

  • Wash your hands well before use.
  • Remove the cap.
  • Tilt your head back a little and pull the lower lid of your eye out to form a pocket.
  • Hold the bottle upside down near to your eye. Try not to touch your eye as you do this.
  • Apply enough pressure to the bottle to release one drop into your eye. (Only if you think that the drop missed your eye should you insert another drop).
  • Close your eye and press gently on the side of your nose where the corner of your eye meets your nose for a minute or two.
  • Repeat the process in your other eye if you have been asked to use the drops in both eyes.
  • Replace the cap.
  • Wash your hands.

Getting the most from your treatment

  • Ketotifen may make you sleepy. If this happens, do not drive or use tools or machines, and do not drink alcohol.
  • If you are using ketotifen eye drops, do not drive or use tools straight after using the drops if your vision is not clear.
  • If you have been given ketotifen eye drops and you usually wear soft (hydrogel) contact lenses, you should wear spectacles instead of your lenses during this treatment.
  • If you buy any medicines, check with a pharmacist that they are safe to take alongside ketotifen.
  • If you are having an operation or any dental treatment, tell the person carrying out the treatment which medicines you are using.

Can ketotifen cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. These usually improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following side-effects continue or become troublesome.

Possible side-effects What can I do if I experience this
Drowsiness, blurred vision Make sure your reactions and sight are normal before driving, operating machinery or doing other jobs which could be dangerous if you were not fully alert or able to see properly
Dry mouth Try chewing sugar-free gum or sweets
Headache Ask your pharmacist to recommend a suitable painkiller. If the headache continues, speak with your doctor
Stomach upset Stick to simple foods - avoid rich or spicy foods
Difficulty passing urine, excitation, irritability, nervousness, and difficulty sleeping Speak with your doctor if any of these become troublesome
Eye irritation (if you are using the eye drops) If this continues, speak with your doctor

If you experience any other symptoms which you think may be due to this medicine, discuss them with your doctor or pharmacist.

How to store ketotifen

  • Keep all medicines out of the sight and reach of children.
  • Store in a cool, dry place, away from direct heat and light.
  • Eye drops should only be used for 4 weeks once the bottle has been opened. Make sure you have a fresh supply after this time.