Ketotifen

Medication antihistamine / mast-cell stabiliser allergy

Aka: Zaditen

Brands seen in Singapore: Tofen, Ketotifen Syrup, Asumalife

Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.

How to use

What it’s for

SG label: allergic rhinitis and chronic urticaria

When to take

SG pharmacy-supply cap: 2 mg a day, up to 10 days

Pros & cons

Pros

Pharmacist supply allowed up to 2 mg a day, 10 days
Cochrane: better asthma and wheeze control in children
Syrup form is registered in SG, from 3 years up

Cons

HSA: all 3 SG ketotifen products are prescription-only
Cochrane: sedation in 21% vs 12% on placebo
Cochrane: weight gain in 27% vs 17% on placebo

Sources

HSA — Listing of Registered Therapeutic Products (data.gov.sg dataset d_767279312753558cbf19d48344577084), Forensicclassification column; all 5,511 rows cached at /tmp/hsa_all.json and filtered locally (never re-fetched), 3 ketotifen rows, 27 Aug 2026 · read 2026-08-27
what it says
“TOFEN TABLET 1 mg (SIN09651P), KETOTIFEN SYRUP 1 mg/5 ml (SIN08766P) and ASUMALIFE SYRUP 1 mg/5 ml (SIN10107P) all read "Prescription Only", ATC R06AX17; no Zaditen-branded ketotifen and no ketotifen eye drop is registered”
MOH National Drug Formulary — TOFEN TABLET 1 MG [SIN09651P], Product information block · read 2026-08-27
what it says
“Forensic Classification: PRESCRIPTION ONLY MEDICINES · Anatomical Therapeutic Chemical (ATC) code R06AX17 · Active Ingredient and Strength: KETOTIFEN FUMARATE EQV KETOTIFEN - 1 MG”
MOH National Drug Formulary — TOFEN TABLET 1 MG [SIN09651P], Prescription-only Medicines with Exemptions for Supply without Prescription · read 2026-08-27
what it says
“As an oral solid preparation not exceeding 2mg. Indications: Symptomatic treatment of allergic rhinitis and chronic urticaria. Maximum daily dose: 2mg. Maximum supply: 10 days. Minimum age: 3 years”
Cochrane Database of Systematic Reviews — Ketotifen alone or as additional medication for long-term control of asthma and wheeze in children (Schwarzer, Bassler, Mitra, Ducharme, Forster, 2004; 26 trials, 1,826 children) · read 2026-08-27
what it says
“ketotifen alone or in combination with other co-interventions improves control of asthma and wheezing in children with mild and moderate asthma … Reported side effects were more frequent in the ketotifen group (sedation: 21%, weight gain: 27%)”
Brain histamine H1 receptor occupancy of orally administered antihistamines measured by PET: a comparison of olopatadine and ketotifen (Tashiro et al., Br J Clin Pharmacol 2006) · read 2026-08-27
what it says
“H(1)R occupancy after olopatadine treatment was significantly lower than that after ketotifen treatment in the all cortical regions … 5 mg oral olopatadine, with its low H(1)R occupancy and thus minimal sedation”
NHS — Antihistamines (conditions A–Z), types and how they work · read 2026-08-27
what it says
“Antihistamines block the effects of a substance called histamine in your body … antihistamines that make you feel sleepy … non-drowsy antihistamines that are less likely to make you feel sleepy”
NHS — Antihistamines: who can take antihistamines · read 2026-08-27
what it says
“speak to a pharmacist or GP for advice if you: are pregnant or breastfeeding … are an older person … have an underlying health condition, such as heart disease, liver disease, kidney disease or epilepsy”
NHS — Antihistamines: taking antihistamines with other medicines, food or alcohol · read 2026-08-27
what it says
“Examples of medicines that could cause problems if taken with antihistamines include some types of: antidepressants; stomach ulcer or indigestion medicines; cough and cold remedies that also contain an antihistamine … Try not to drink alcohol”

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Updated 2026-08-29. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.

In Singapore

Classification
HSA register

prescription-only

This is the Singapore classification, taken from the HSA register. Dosing stays with the label and your pharmacist or doctor — this page never tells you how much to take.

What the label says

The Singapore label maximum sits in the exemption block of the moh national drug formulary page for TOFEN TABLET 1 MG [SIN09651P], which reads "As an oral solid preparation not exceeding 2mg — Indications: Symptomatic treatment of allergic rhinitis and chronic urticaria — Maximum daily dose: 2mg — Maximum supply: 10 days — Minimum age: 3 years". that 2 mg a day is the ceiling for supply without a prescription, not a prescriber ceiling: the forensic classification on the SAMe page is "PRESCRIPTION ONLY MEDICINES", and the ndf page carries no posology section for this product, so no full label dosing schedule could be quoted. the cochrane review of children's asthma trials describes oral doses of "not less than one mg daily" given for 10 to 32 weeks. in Singapore the prescriber or pharmacist sets the dose.

Who should check first

Talk to a doctor or pharmacist before taking this if any of these apply to you.

Under 3 years: the SG supply exemption starts at 3 years
Sedation is common: cochrane reported it in 21% of children treated
Pregnancy or breastfeeding: NHS: pharmacist or gp advice first
Older age, heart, liver or kidney disease or epilepsy: NHS advises asking first

Documented interactions

With medicines and supplements

Antidepressants, indigestion or ulcer medicines: NHS lists these among medicines that could cause problems taken with antihistamines⁸
Cough and cold remedies containing an antihistamine: NHS flags doubling up on antihistamine through an all-in-one remedy⁸

With food and drink

Alcohol: NHS advises against it with any antihistamine, particularly a sedating one, as it raises the chance of sleepiness⁸

Only combinations someone has written down appear here. A pair that is missing is unrecorded, not cleared.