HISTOFEN 1/MG/5/ML SYRUP 100ML

Indications

Approved Uses

Temporary prevention of itching of the eye due to allergic conjunctivitis

Off-Label Uses

For this ophthalmic product, off-label use is uncommon; systemic (oral) ketotifen has been used off-label for chronic urticaria and mast-cell-mediated disorders (e.g., MCAS) under specialist care, but that does not apply to this ocular formulation.

Dosage & Administration

Dosing by Condition

Allergic conjunctivitis: instill 1 drop in the affected eye(s) twice daily.

Initial Dose

Ophthalmic: 1 drop in each affected eye twice daily

Maintenance Dose

Ophthalmic: 1 drop (0.025 mg) in each affected eye twice daily

Maximum Dose

Ophthalmic: 1 drop (0.025 mg) in each affected eye twice daily, up to 12 hours apart

Children's Dosage

Ophthalmic: Children ≥3 years: 1 drop in each affected eye twice daily

How to Take

This SFDA-registered product is ketotifen ophthalmic (ATC S01GX08; ocular use): instill 1 drop into the affected eye(s) twice daily (about every 8-12 hours); wash hands, avoid touching the dropper tip, remove contact lenses and reinsert after ~15 minutes, and recap immediately after use.

Side Effects

Common Side Effects

Mild burning/stinging, eye irritation, dry eyes, conjunctival injection.

Side Effect Frequency

Ophthalmic: Common: eye irritation, burning/stinging, dry eyes. Uncommon: headache, vision blurred, conjunctivitis. Systemic effects rare with ophthalmic use.

Safety & Warnings

Contraindications

Hypersensitivity to ketotifen or any excipient.

Warnings & Precautions

Avoid in contact lens wearers if eyes red; discontinue if no improvement in 3 days or worsening; not for contact lens irritation.

Drug Interactions

Drug Interactions

Contact lenses (delay insertion 10-15 min); avoid if eyes red.

Special Populations

Pregnancy

Consult Doctor

Breastfeeding

Caution

Children

Ophthalmic: Children ≥3 years: 1 drop in each affected eye twice daily

Storage & Patient Advice

Missed Dose

Take as soon as remembered; skip if near next dose. Do not take two doses at once.

Overdose

Ophthalmic overdose unlikely; if significant ingestion: supportive care, consider activated charcoal if recent

Patient Counseling

Use as eye drops (not by mouth): instill 1 drop twice daily; avoid contaminating the dropper tip; remove contact lenses and reinsert after ~15 minutes; transient stinging/irritation may occur; if drowsiness occurs, avoid driving; seek care for severe eye pain, vision changes, or no improvement.

Monitoring Requirements

No routine laboratory monitoring for ophthalmic ketotifen; consider platelet count monitoring only if a patient is also taking oral antidiabetic agents and is using systemic (oral) ketotifen (rarely relevant to eye drops).

Pharmacology

Mechanism of Action

Non-competitive H1 receptor antagonist with mast-cell stabilizing activity that inhibits release of allergic mediators (e.g., histamine, leukotrienes) and reduces ocular allergic inflammation.

Onset of Action

Symptom relief for allergic conjunctivitis typically begins within minutes to a few hours; maximal benefit may require several days of regular use (weeks-long onset applies to oral asthma prophylaxis, not ophthalmic use).

Duration of Effect

Approximately 8-12 hours per dose (supports twice-daily dosing).

Bioavailability

Approximately 50% due to first-pass hepatic metabolism.

Excretion

Systemic ketotifen is primarily eliminated renally, largely as metabolites (commonly cited >60%); for ophthalmic use, systemic exposure is low so excretion details are usually not clinically relevant.

Protein Binding

Approximately 75%

Product Information

Available Dosage Forms

Eye drops

Composition per Dose

Each drop (0.05 ml): 0.01 mg ketotifen (0.2 mg/ml strength)

Generic Availability

Yes

OTC Alternatives

OTC alternatives for allergic conjunctivitis include ophthalmic antihistamine/mast-cell stabilizers such as olopatadine, azelastine, and sodium cromoglicate; oral OTC antihistamines (cetirizine/loratadine/fexofenadine) may help systemic allergy symptoms but are not direct ocular equivalents.

Symptom Target

Allergic conjunctivitis, ocular itching

Sedating

Yes

Reviewed by Al Mujtama Pharmacy Medical Review Team. Last reviewed 27-07-2026