Conjunctivitis - Allergic, Seasonal & Perennial Tóm tắt về thuốc

Cập nhật: 24 March 2026

Antihistamines & Antiallergics

Drug Dosage Remarks
Bilastine 20 mg PO 24 hourly Adverse Reactions
  • CNS effects (headache, somnolence, dizziness); Other effect (fatigue)
Special Instructions
  • Avoid use with P-glycoprotein inhibitors in patients with moderate or severe renal impairment
  • May affect ability to drive or operate machinery
Cetirizine 5 mg PO 12 hourly or
10 mg PO 24 hourly		 Adverse Reactions
  • CNS effects (headache, dizziness, agitation); GI effects (dry mouth, GI discomfort)
Special Instructions
  • Avoid intake with alcoholic beverages
  • Avoid in patients with hepatic and renal impairment, prostatic hypertrophy, urinary retention and glaucoma, history of unusual severe reactions such as excessive sedation or CNS stimulation, narrow-angle glaucoma
Chlorpheniramine maleate 4 mg PO 4-6 hourly
Max dose: 24 mg/day		 Adverse Reactions
  • CNS effect (sedation); GI effects (nausea, epigastric pain); Other effects (increased sensitivity to sunlight, hypotension, loss of appetite)
Special Instructions
  • Avoid concomitant therapy with monoamine oxidase inhibitor (MAOI)
  • Use with caution in patients with hepatic disease, narrow-angle glaucoma, severe hypertension, CV disease, acute asthma, bronchitis, bronchiectasis, thyrotoxicosis, urinary retention, prostatic hypertrophy, bladder neck obstruction
  • May impair ability to drive or operate machinery
Clemastine 1 mg PO 12 hourly Adverse Reactions
  • CNS effects (drowsiness, dizziness, confusion); CV effects (changes in BP, palpitations, arrhythmias); GI effects (dry mouth, constipation, increased gastric reflux); Other effects (blurred vision, urinary difficulty or retention, sweating, paradoxical excitation)
Special Instructions
  • May impair ability to drive or operate machinery
Dexchlorpheniramine 2 mg PO 4-6 hourly
Max dose: 12 mg/day		 Adverse Reactions
  • Dermatologic effects (urticaria, drug rash, photosensitivity); Other effects (drowsiness, anaphylactic shock, excessive perspiration, dry mouth and nose, severe hypotension)
Special Instructions
  • Avoid in patients on MAOI therapy
  • Use with caution in patients with narrow-angle glaucoma, stenosing peptic ulcer, pyloroduodenal obstruction, prostatic hypertrophy or bladder neck obstruction, CV disease, increased IOP; hyperthyroidism
Diphenhydramine 25-50 mg PO 6-8 hourly
Max dose: 300 mg/day		 Adverse Reactions
  • CNS effects (sedation, dizziness); GI effects (nausea/vomiting, diarrhea, constipation, epigastric pain); Renal effects (urinary frequency, difficult urination, urinary retention); Other effects (hypotension, muscular weakness, incoordination)
Special Instructions
  • Contraindicated in patients with narrow-angle glaucoma, asthma, prostatic hypertrophy, bladder neck obstruction, porphyria, stenosing peptic ulcer, pyloroduodenal obstruction
  • Use with caution in patients with increased IOP, hyperthyroidism, CV disease, hypertension, liver disease (cirrhosis), urinary retention, myasthenia gravis, seizure disorders, moderate to severe renal impairment
  • May impair ability to drive or operate machinery
Loratadine 10 mg PO 24 hourly Adverse Reactions
  • GI effects (nausea, diarrhea, abdominal pain, dry mouth); CNS effects (dizziness, headache, somnolence); Other effects (fatigue, itching)
Special Instructions
  • Avoid intake with alcoholic beverages
  • Use with caution in patients with hepatitis
  • Discontinue if cardiac arrhythmias occur
Mebhydrolin 50-100 mg PO 8 hourly Adverse Reactions
  • CNS effects (drowsiness, headache, CNS stimulation); GI effects (dry mouth, loss of appetite, GI disturbance); Other effects (fatigue, hypotension, tinnitus, reversible blood dyscrasia, allergic reactions)
Special Instructions
  • Avoid in patients with acute asthma
  • Use with caution in patients with narrow-angle glaucoma, urinary retention, prostate hypertrophy, focal lesion of cerebral cortex, DM
  • May impair ability to drive or operate machinery
Promethazine 20-75 mg PO 24 hourly or
10-20 mg PO 8-12 hourly		 Adverse Reactions
  • CNS effects (sedation, inability to concentrate, lassitude, dizziness, headache, muscular weakness, incoordination, elation, depression); GI effects (dry mouth, GI disturbances); Other effects (hypotension, blurred vision, tinnitus, irritability, nightmares, anorexia, difficulty in micturition, tightness of chest, tingling, heaviness and weakness of hands)
Special Instructions
  • Avoid in coma, CNS depression, MAOI therapy within 14 days
  • Use with caution in patients with narrow-angle glaucoma, hyperthyroidism, CV disease, prostatic hypertrophy, stenosing peptic ulcer, pyloroduodenal obstruction, bladder neck obstruction, hypersensitivity to sulfites
  • May impair ability to drive or operate machinery
Other Antihistamine
Ketotifen 1 mg PO 12 hourly Adverse Reactions
  • CNS effects (drowsiness; dizziness; occasionally, CNS stimulation); Other effects (dry mouth, increased appetite, weight gain)
Special Instructions
  • Avoid abrupt discontinuation
  • Avoid in patients on oral antidiabetic treatment, acute attacks of asthma
  • May impair ability to drive or operate machinery

Eye Corticosteroids

Drug Available Strength Dosage Remarks
Betamethasone 0.1% ophthalmic solution Instill 1-2 drops 1-2 hourly, then reduce frequency when the condition is controlled Adverse Reactions
  • Increased IOP that is dependent on concentration, frequency and duration of use
  • Can lead to secondary open-angle glaucoma (irreversible optic nerve damage and possible irreversible blindness)
  • May slow corneal wound healing; infection of the cornea/conjunctiva; cataract formation
  • Rarely: Transient stinging, burning; ocular discharge, potential for systemic side effects
Special Instructions
  • Avoid in untreated infections
  • Should be given and supervised by an ophthalmologist
  • Should be used with caution and only in severe cases of allergic conjunctivitis
  • Short-course pulse treatment is preferred during the acute symptomatic phase and is desirable rather than prolonged chronic treatment
Dexamethasone 0.1% ophthalmic drops, suspension Instill 1-2 drops 4-6 hourly
0.1% ointment Apply 1-1.5 cm into the conjunctival sac up to 6 hourly
Fluorometholone 0.1% ophthalmic drops, suspension Instill 1-2 drops 6-12 hourly
0.02% ophthalmic suspension Instill 1-2 drops 6-12 hourly
Loteprednol etabonate 0.2% ophthalmic suspension Instill 1-2 drops 6 hourly
0.5% ophthalmic drops Instill 1-2 drops 6 hourly
Prednisolone 1% ophthalmic drops, suspension Instill 2 drops 6 hourly
1Combination preparations are available. Please see the latest MIMS for specific formulations and prescribing information.

Ophthalmic Decongestants

Drug Available Strength Dosage Remarks
Antihistamines/Mast Cell Stabilizers
Azelastine 0.05% ophthalmic solution Instill 1 drop 12 hourly Adverse Reactions
  • Local effects (transient ocular burning/stinging, blurred vision, dry eye, tearing); CNS effects (headache, somnolence); Other effects (taste disturbances, nausea, dry mouth)
Special Instructions
  • Not indicated for eye infections
  • Remove contact lenses before application and wait at least 10 minutes before reinsertion
Bepotastine 1.5% ophthalmic solution Instill 1 drop 12 hourly Adverse Reactions
  • Local effect (eye irritation); CNS effect (headache); Other effects (dysgeusia, nasopharyngitis)
Special Instructions
  • Remove contact lens prior to administration then reinsert after 10 minutes
Cetirizine 0.24% ophthalmic solution Instill 1 drop 12 hourly Adverse Reactions
  • Local effect (eye irritation, decreased visual activity, ocular hyperemia)
Special Instructions
  • Remove contact lens prior to administration then reinsert after 10 minutes
Epinastine 0.05% ophthalmic solution Instill 1 drop 12 hourly Adverse Reactions
  • Local effects (burning sensation, hyperemia, discharge, visual disturbance); Other effects (headache, rhinitis)
  • Ketotifen may cause somnolence, allergic reactions
Special Instructions
  • Avoid concomitant use with antidiabetic agents
  • Use with caution in patients who will drive or operate machineries
  • Remove contact lens prior to administration then reinsert after 10 minutes
Ketotifen 0.025% ophthalmic solution Instill 1 drop 12 hourly
Olopatadine 0.1% ophthalmic solution Instill 1-2 drops 12 hourly Adverse Reactions
  • Local effects (burning sensation, dry eyes, eye pain, visual disturbance); Other effects (headache, asthenia, rhinitis, sinusitis)
Special Instructions
  • Remove contact lens prior to administration then reinsert after 10 minutes
0.2% ophthalmic solution Instill 1 drop 24 hourly
0.7% ophthalmic solution Instill 1 drop 24 hourly
Antihistamines/Vasoconstrictors
Antazoline/Naphazoline 0.5/0.05% ophthalmic solution Instill 1 drop 6-8 hourly Adverse Reactions
  • Local effects (conjunctival irritation, hyperemia)
Special Instructions
  • Avoid use in patients with angle-closure glaucoma
  • Use with caution in patients with CV disease, DM, hypertension, hyperthyroidism, serious eye disease or infection
Antazoline/Tetryzoline
(Antazoline/Tetrahydrozoline)		 0.05%/0.04% ophthalmic drops Acute treatment:
Instill 1 drop 3 hourly
Maintenance therapy:
Instill 1 drop 8-12 hourly
Severe cases:
Instill 1 drop 1 hourly		 Adverse Reactions
  • Local effects (transient burning sensation, mydriasis, hyperemia); CNS effects (headache, drowsiness)
Special Instructions
  • Avoid use in patients with narrow-angle glaucoma or dry eye syndrome and concomitant use with MAOIs
  • Use with caution in patients with DM, hypertension, severe heart disease, hyperthyroidism, pheochromocytoma, rhinitis sicca, chronic and recurring allergies
  • Remove contact lens prior to administration then reinsert after 15 minutes
Pheniramine/Naphazoline 0.3%/0.025% ophthalmic drops Instill 1-2 drops 3-6 hourly or less frequently Adverse Reactions
  • Local effects (pupillary dilation, increased IOP)
Special Instructions
  • Avoid use in patients with narrow-angle/angle-closure glaucoma
  • Use with caution in patients with severe CV disease, DM, poorly controlled hypertension
Mast Cell Stabilizers
Cromoglicic acid1
(Cromolyn Na, Cromolyn,
Disodium cromoglycate,
Na cromoglycate, Sodium cromoglicate)		 2% ophthalmic drops Instill 1-2 drops 4-6 hourly Adverse Reactions
  • Local effects (transient ocular burning/stinging, pruritus, erythema)
Special Instructions
  • Avoid use with contact lens
  • Use with caution in patients with renal or hepatic disorders
4% ophthalmic solution Instill 2 drops 4-6 hourly
4% ophthalmic ointment Apply 8-12 hourly
Lodoxamide 0.1% ophthalmic drops Instill 1-2 drops 6 hourly
Nedocromil sodium 2% ophthalmic solution Instill 1-2 drops 12 hourly Adverse Reactions
  • Local effects (ocular burning/stinging/irritation, conjunctivitis, eye redness, photophobia); CNS effect (headache); Respiratory effects (asthma, nasal congestion, rhinitis); Other effect (taste disturbance)
Special Instructions
  • Avoid use with contact lens
Pemirolast 0.1% ophthalmic drops Instill 1 drop 12 hourly Adverse Reactions
  • Local effects (transient ocular burning/stinging, pruritus, erythema, blepharitis, palpebral dermatitis)
Special Instructions
  • Avoid use with contact lens
  • Discontinue if irritation occurs
Nonsteroidal Anti-inflammatory Drugs
Diclofenac 0.1% ophthalmic solution Instill 1 drop 6 hourly Adverse Reactions
  • Local effects (blurring of vision, transient burning/stinging of the eyes, lacrimation, increased IOP, keratitis); Hematologic effects (anemia, blood dyscrasias); Other effects (sodium and fluid retention, risk of hyperkalemia, hypertension, edema, liver function abnormalities)
Special Instructions
  • Avoid in patients with Aspirin-sensitive asthma, moderate to severe heart failure, ischemic heart disease, peripheral arterial disease, cerebrovascular disease, GI ulceration, treatment in the setting of coronary artery bypass grafting (CABG), concomitant use of other nonsteroidal anti-inflammatory drugs (NSAIDs), antiplatelets, anticoagulants, severe hepatic or renal impairment
  • Use with caution in patients with GI bleeding or peptic ulceration, coagulopathy, current or risk factors for CV disease, dehydration, resp tract infections, systemic lupus erythematosus, ocular disease
Ketorolac 0.5% ophthalmic drops Instill 1 drop 6 hourly Adverse Reactions
  • Local effects (transient ocular burning/stinging, irritation, allergic reactions, ocular infection, superficial keratitis)
Special Instructions
  • Avoid in patients with history of asthma, active or history of peptic ulcer disease, recent or history of GI bleeding or perforation, suspected or confirmed cerebrovascular bleeding, hemorrhagic diathesis, incomplete hemostasis, high risk of bleeding, complete or partial syndrome of nasal polyps, angioedema or bronchospasm, moderate to severe renal impairment, concomitant use with Probenecid, Lithium, Pentoxifylline, anticoagulants, other NSAIDs or Aspirin
  • Avoid use with contact lens
  • Use with caution in patients with bleeding tendencies or receiving medication that prolongs bleeding time
Vasoconstrictors
Naphazoline 0.05%, 0.01%, 0.1% ophthalmic solution, drops Instill 1-2 drops 3-4 hourly Adverse Reactions
  • Local effects (pupillary dilation, increase in IOP, hyperemia, irritation); Other effects (hypersensitivity reactions, hypertension, hyperglycemia, drowsiness)
  • Tetryzoline may also cause nausea/vomiting, headache, rebound congestion
Special Instructions
  • Naphazoline: Avoid use in patients with narrow-angle glaucoma, corneal damage, acute iritis and other serious eye disease
  • Tetryzoline: Do not use if the patient has or had glaucoma or scratched cornea
  • Use with caution in patients with hypertension, DM, cardiac irregularities, hyperthyroidism
  • Remove contact lens prior to administration
0.012% ophthalmic drops Instill 1-2 drops up to 6 hourly
Tetryzoline
(Tetrahydrozoline)		 0.05% ophthalmic drops Instill 1-2 drops 6 hourly
Other Antiallergics
Alcaftadine 0.25% ophthalmic solution Instill 1 drop 24 hourly Adverse Reactions
  • Local effects (irritation, burning and/or stinging, eye erythema and pruritus); Other effects (nasopharyngitis, headache)
Special Instructions
  • Administer concomitant ocular medications at least 5 minutes apart
  • Not for the treatment of contact lens-related irritation
  • Remove contact lens prior to administration then reinsert after 10 minutes
  • Use with caution in patients who will drive or operate machineries
Emedastine 0.05% ophthalmic solution Instill 1 drop 6 hourly Adverse Reactions
  • Local effects (transient ocular burning/stinging, blurred vision, dry eye, tearing); Other effects (headache, asthenia, rhinitis, abnormal dreams)
Special Instructions
  • Use with caution in patients with renal or hepatic impairment
  • Remove contact lens prior to administration then reinsert after 10 minutes
Levocabastine 0.05% ophthalmic suspension Instill 1 drop 6-12 hourly Adverse Reactions
  • Local effects (stinging and burning of the eyes); CNS effects (drowsiness, headache); Other effects (urticaria, dyspnea)
Special Instructions
  • Use with caution in pregnant patients
Tranilast 0.5% ophthalmic drops Instill 6 hourly Adverse Reactions
  • Local effects (irritation and blepharitis); CNS effects (headache, dizziness, drowsiness or insomnia); Other effects (GI disturbances, malaise, skin rashes, generalized pruritus)
Special Instructions
  • Use with caution in patients with hepatic and renal impairment
1Combination with Benzalkonium Cl is available. Please see the latest MIMS for specific formulations and prescribing information.

Ophthalmic Lubricants

Drug Dosage Remarks
Ectoin Instill 1-2 drops several times daily Adverse Reactions
  • Local effects (eye irritation, ocular hyperemia, conjunctivitis)
Special Instructions
  • Do not use in case of hypersensitivity, after eye surgery or trauma
  • Discontinue if allergic reactions occur

Disclaimer

All dosage recommendations are for non-pregnant and non-breastfeeding women, and non-elderly adults with normal renal and hepatic function unless otherwise stated.  
Not all products are available or approved for above use in all countries.  
Products listed in the Drug Summary are based on indications stated in the locally approved product monographs.   
Please refer to local product monographs in Related MIMS Drugs for country-specific prescribing information.  

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