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Updated 2 Feb 2023 | Sedating antihistamines

Drugs List

  • ketotifen 1mg tablets
  • ketotifen 1mg/5ml oral solution sugar-free
  • ZADITEN 1mg tablets
  • ZADITEN 1mg/5ml elixir sugar-free
  • Therapeutic Indications


    Symptomatic treatment of allergic conditions including rhinitis and conjunctivitis.



    1mg twice daily with food. If necessary, dose can be increased to 2mg twice daily.

    Patients known to be easily sedated should be given 0.5mg to 1mg at night for the first few days.


    No dose modification required (see Dosage - Adults)


    Children 3 years and over:
    1mg twice daily with food.
    Oral solution may be more suitable for children.

    Children under 3 years:


    Children under 3 years
    Pregnancy (see Pregnancy)
    Breastfeeding (see Lactation)

    Precautions and Warnings

    Convulsions have been reported vary rarely during ketotifen therapy. As ketotifen may lower the seizure threshold, it should be used with caution in patients with a history of epilepsy.

    Patients, especially those taking the oral solution (elixir), should avoid alcoholic drinks.

    Oral solution (elixir) contains alcohol.

    Oral solution contains methyl and propyl hydroxybenzoates, which may cause allergic reactions in some patients.

    Oral solution contains maltitol and therefore should not be administered to patients with hereditary fructose intolerance.

    Some formulations contain lactose and therefore should not be administered to patients with galactosaemia. Use caution in patients with lactose intolerance and glucose-galactose malabsorption syndrome.

    During the first few days of treatment, reactions may be impaired. Patients should be warned not to take charge of vehicles or machinery until effect of ketotifen treatment on the individual is known.

    Pregnancy and Lactation


    Due to a lack of information concerning safety in pregnancy, ketotifen oral formulations are contraindicated in pregnancy.

    The use of all medication in pregnancy should be avoided whenever possible; particularly in the first trimester. Non-drug treatments should also be considered. When essential, a medication with the best safety record over time should be chosen, employing the lowest effective dose for the shortest possible time. Polypharmacy should be avoided. Teratogens taken in the pre-embryonic period, often quoted as lasting until 14-17 days post-conception, are believed to have an all-or-nothing effect. Where drugs have a short half-life, and when the date of conception is certain, this may allow women to be reassured where drug exposure has occurred within this time frame. Further advice may be available from the UK National Teratology Information Service (NTIS) and through ToxBase, available via password on the internet ( ) or if this is unavailable at the backup site ( ).


    Ketotifen is excreted in breast milk and is contraindicated in breast feeding women.

    Neonates, infants born prematurely, those with low birth weight, those with an unstable gastrointestinal function or who have serious illnesses may require special consideration. For any infant, if a drug is prescribed to the nursing mother, it should be at the lowest practical dose and for the shortest time. When drug administration is unavoidable and breastfeeding is to continue, minimisation of exposure of the infant to the drug may sometimes be achieved by timing the maternal doses to just after a feeding episode. Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms. Interactions between the drug received by the infant from the mother's milk and medication prescribed for the infant should also be considered, for example, when the drug given to the infant may prevent metabolism of the drug received via breast milk.
    Specialist advice is available from the UK Drugs in Lactation Advisory Service at

    Effects on Ability to Drive and Operate Machinery

    As reactions may be impaired, patients should be advised not to drive or operate machinery until the effect of the treatment is known.


    Patients should be warned not to take charge of vehicles or machinery until effect of ketotifen treatment on the individual is known. Reactions may be impaired during the first few days of treatment.

    Advise patients, especially those taking the oral solution (elixir), to avoid alcoholic drinks.

    Side Effects

    Dry mouth
    CNS stimulation
    Weight gain
    Increases in hepatic enzymes
    Erythema multiforme
    Stevens-Johnson syndrome
    Skin reactions


    It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.

    The following number will direct the caller to the relevant local centre (0844) 892 0111

    Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet ( ) or if this is unavailable at the backup site ( ).

    Shelf Life and Storage

    Store below 25 degrees C

    Further Information

    Last Full Review Date: December 2011

    Reference Sources

    British National Formulary, 62nd Edition (2011) Pharmaceutical Press, London.

    BNF for Children (2011-2012) Pharmaceutical Press, London.

    Summary of Product Characteristics: Zaditen elixir 1mg/5ml. Defiante Farmaceutica. Revised October 2009.

    Summary of Product Characteristics: Zaditen tablets 1mg. Defiante Farmaceutica. Revised October 2009.

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    Medscape UK | Univadis prescription drug monographs & interactions are based on FDB Multilex Content

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    FDB Disclaimer : FDB Multilex is intended for the use of healthcare professionals and is provided on the basis that the healthcare professionals will retain FULL and SOLE responsibility for deciding what treatment to prescribe or dispense for any particular patient or circumstance.