Tobradex (Dexamethasone/Tobramycin)
Is It Right for You?
A complete guide to Tobradex (Dexamethasone/Tobramycin) — what it treats, how it works, dosages, side effects, and when a clinician may prescribe it following an online consultation.
What Is Tobradex?
Tobradex is a combination ophthalmic (eye) preparation containing two active ingredients: tobramycin 0.3%, an aminoglycoside antibiotic, and dexamethasone 0.1%, a potent corticosteroid. It is available as both eye drops (suspension) and eye ointment and is used to treat bacterial eye infections that are accompanied by significant inflammation.
The rationale for this combination is that many bacterial eye conditions — such as blepharoconjunctivitis, bacterial conjunctivitis with a marked inflammatory component, and post-operative eye inflammation with infection risk — require both antibacterial activity to eliminate the causative organisms and anti-inflammatory action to reduce redness, swelling, and discomfort and to prevent complications such as corneal scarring.
Tobramycin provides broad-spectrum antibacterial coverage against the Gram-positive and Gram-negative bacteria most commonly responsible for external ocular infections. Dexamethasone suppresses the immune-mediated inflammatory cascade that would otherwise cause prolonged redness, swelling, photophobia, and potential tissue damage.
Tobradex is a prescription-only medication in the UK. Its use is restricted to confirmed or strongly suspected bacterial infection with a clinically significant inflammatory component. Inappropriate use of steroid-containing eye preparations can cause serious complications including glaucoma and cataracts.
What Conditions Is Tobradex Used For?
Tobradex is indicated for:
the primary licensed indication; situations where both antibacterial and anti-inflammatory treatment are simultaneously required.
inflammation of both the eyelids and conjunctiva with associated bacterial infection.
red, discharging eyes with notable swelling where the inflammatory response is clinically significant.
The corticosteroid component of Tobradex can mask symptoms and dramatically worsen viral eye infections — particularly herpes simplex keratitis — and fungal eye infections. These conditions must be excluded before Tobradex is used. If an eye condition worsens on Tobradex, discontinue and seek urgent ophthalmological review.
How Does Tobradex Work?
Tobramycin is an aminoglycoside antibiotic that works by binding to the 30S subunit of the bacterial ribosome, causing misreading of the genetic code during protein synthesis. This results in the production of faulty bacterial proteins, disruption of the bacterial cell membrane, and ultimately bacterial cell death. It is bactericidal — killing bacteria rather than merely inhibiting their growth. Tobramycin has broad-spectrum activity against many common ocular pathogens including Staphylococcus aureus, Streptococcus species, Haemophilus influenzae, Pseudomonas aeruginosa, and Escherichia coli.
Dexamethasone is a synthetic glucocorticoid corticosteroid that suppresses inflammation by binding to intracellular glucocorticoid receptors, which then modulate gene expression to reduce the production of pro-inflammatory cytokines, prostaglandins, and leukotrienes. This results in a reduction in vasodilation, vascular permeability, cellular infiltration, and the associated symptoms of redness, swelling, discharge, photophobia, and pain. Dexamethasone is one of the most potent ophthalmic corticosteroids available.
Together, these mechanisms address both the infective cause and the inflammatory consequences of the ocular condition simultaneously, producing faster clinical resolution than either agent alone.
Dosages & Administration
The correct dose depends on the type and severity of infection, age, weight, and kidney function. Always follow your clinician's instructions. The table below is for general reference only.
Administration Tips
Shake eye drops well before each use — Tobradex suspension separates on standing and must be mixed before application.
Wash hands thoroughly before and after applying eye drops or ointment.
Tilt your head back, pull down the lower eyelid, and apply drops into the pocket between the eyelid and the eye. Avoid touching the dropper tip to the eye, eyelid, or any surface, as this contaminates the bottle.
Apply gentle pressure to the inner corner of the eye (nasolacrimal occlusion) for 1–2 minutes after instilling drops, to reduce systemic absorption via the tear duct.
Do not wear contact lenses during treatment with Tobradex. Tobramycin may be absorbed by soft contact lenses, and the preservative benzalkonium chloride can damage them and cause eye irritation
Side Effects of Tobradex
Common side effects include temporary blurred vision after application, eye irritation, stinging, or burning on instillation, and increased lacrimation. Serious side effects may include raised intraocular pressure and delayed healing.
- Temporary blurred vision after application
- Eye irritation, stinging, or burning on instillation
- Increased lacrimation
- Eyelid itching or swelling
- Photophobia
- Raised intraocular pressure — corticosteroids can increase intraocular pressure, risking optic nerve damage and permanent vision loss.
Corticosteroid eye preparations can cause significant rises in intraocular pressure, particularly with prolonged use. Intraocular pressure should be measured at the start of treatment and monitored regularly during courses lasting longer than 10 days.
Drug Interactions
Drug interactions with topically applied ophthalmic preparations are generally limited due to low systemic absorption. However, if using multiple eye drops, space applications at least 5–10 minutes apart to prevent the first medication from being diluted or washed away before absorption.
If using multiple eye drops, space applications at least 5–10 minutes apart to prevent the first medication from being diluted or washed away before absorption. Ointments should generally be applied last.
Concurrent use of systemic steroids with ophthalmic dexamethasone may additively increase systemic corticosteroid effects and risk of adrenal suppression, particularly in children.
If receiving systemic aminoglycoside therapy concurrently, total drug exposure should be considered, though this is rarely clinically significant with ocular tobramycin.
Benzalkonium chloride preservative in Tobradex eye drops can damage soft contact lenses. Do not insert contact lenses while using Tobradex.
Important Warnings
The corticosteroid (dexamethasone) in Tobradex will suppress immune responses to viral and fungal pathogens, potentially allowing these infections to spread and cause severe, vision-threatening damage. Herpes simplex viral keratitis in particular is dramatically worsened by steroid use. Tobradex must only be used when bacterial infection has been confirmed or is strongly suspected by a clinician.
Ocular corticosteroids can cause significant rises in intraocular pressure, particularly with prolonged use. Undetected pressure rises can damage the optic nerve and cause permanent vision loss. Intraocular pressure must be monitored during treatment exceeding 10 days.
Tobradex should not be used longer than prescribed without specialist review. Prolonged steroid use increases the risk of glaucoma, cataracts, and susceptibility to opportunistic infection.
Tobradex should be used with caution in children. The systemic absorption of corticosteroids through the eyes may be proportionally greater in children than adults, increasing the risk of adrenal suppression with prolonged use.
Speak to a Clinician About Treatment
Getting advice no longer means sitting in a waiting room. Through The GP Service, you can consult with a licensed clinician in minutes — from home, on your lunch break, or wherever works for you. If treatment is clinically appropriate, your clinician can issue a prescription during the consultation. A consultation does not guarantee a prescription.
The treatment you need, when you need it.
Tobradex FAQs
Yes. A clinician can assess your eye symptoms via a telehealth consultation and prescribe Tobradex if the clinical picture is appropriate. Clear symptom description and — where possible — photographs of the affected eye can help clinicians make an accurate assessment remotely.
Temporary blurring is common — particularly with the ointment formulation — due to the oily base coating the eye surface. This resolves within a few minutes. Avoid driving or using machinery until vision has cleared after each application.
Most patients notice a reduction in redness, discharge, and discomfort within 24–48 hours of starting treatment. Full resolution of the infection typically occurs within 7–14 days.
No. Contact lenses should not be worn during treatment. The preservative in the drops can damage soft lenses, and lens wear during an eye infection can worsen the condition. Wait at least 24 hours after completing the course before reinserting lenses.
If your symptoms worsen or you develop increased pain, photophobia, or deteriorating vision, stop treatment and seek urgent ophthalmological review. Worsening may indicate a viral or fungal infection, a steroid pressure rise, or inadequate antibiotic cover.
No. Eye drops become contaminated after opening and should be discarded after the prescribed course. A new infection requires a new clinical assessment — the cause may be different, and using leftover steroid-containing drops without a diagnosis could be dangerous.