What is the difference between TobraDex and Zylet?

Both contain tobramycin. TobraDex uses dexamethasone (stronger, higher IOP risk). Zylet uses loteprednol (lower average IOP risk, better for longer courses). Both require IOP monitoring.

What is Maxitrol and when is it used?

Maxitrol is neomycin/polymyxin B/dexamethasone. It provides broader gram-negative coverage but carries a higher risk of neomycin contact allergy. Worsening lid eczema or itching after starting may indicate allergy.

Should combination drops be used for corneal ulcers?

Usually not initially. Start with intensive standalone antibiotics. Consider adding steroid only after improvement and after excluding viral or fungal disease, often with specialist input for higher-risk cases.

Do antibiotic-steroid combination drops raise eye pressure?

Yes. Dexamethasone combinations (TobraDex, Maxitrol) carry higher IOP risk than loteprednol combinations (Zylet). Check IOP at follow-up, especially for courses beyond 7–10 days or in steroid responders.

When should I use a standalone antibiotic vs a combination drop?

Standalone antibiotic when infection is the primary concern or diagnosis is uncertain. Combination when you need both coverage and inflammation control and the etiology is clear. Standalone steroid when infection is not a concern.

What follow-up is appropriate when starting a combination drop?

Higher-risk presentations and corneal staining warrant 1–3 day follow-up. Post-surgical use with a clean exam typically follows up within a week. If not improving, reassess the diagnosis before extending steroid exposure.

Is there a generic for TobraDex?

Yes. Generic tobramycin/dexamethasone suspension is widely available and much less expensive than branded TobraDex. TobraDex ST does not currently have a direct generic equivalent.

Antibiotic and Steroid Combination Eye Drops

TobraDex, Zylet, Maxitrol, and Pred-G compared by steroid risk and coverage

TobraDex, Zylet, Maxitrol: When to Use and How to Choose

When combination drops make sense

Fixed antibiotic-steroid combinations are used when two goals are present at the same time: you need antibacterial coverage and you also need to control clinically meaningful surface inflammation. The antibiotic reduces bacterial load, while the steroid reduces chemosis, injection, and discomfort. A single bottle simplifies dosing and improves adherence compared with prescribing separate drops. The key clinical decision is whether the epithelium is intact and whether the etiology is clear enough to safely include a steroid from the start.

Common indications

Combination therapy is most appropriate when the presentation is primarily external and you are confident you are not missing HSV, fungal, or atypical keratitis. Common indications include:

Post-surgical prophylaxis and inflammation: one of the most common uses. After cataract surgery or other anterior segment procedures, a combination drop provides infection prophylaxis and inflammation control in a single regimen.
Staphylococcal blepharoconjunctivitis with marked lid margin inflammation and a suspected bacterial component.
Marginal keratitis related to lid disease when the exam supports a sterile inflammatory process driven by bacterial antigen load.
Selected contact lens related inflammatory events when infection has been reasonably excluded and follow-up is planned.

If the main need is antimicrobial coverage without significant inflammation, start with a standalone antibiotic from the antibiotics page. If the main need is anti-inflammatory control and infection is not a concern, a standalone steroid from the steroids page may be more appropriate.

Comparing products: TobraDex, TobraDex ST, Zylet, Maxitrol, and Pred-G

In routine external disease, product selection is often driven more by the steroid risk profile and surface tolerance than by small differences in antibacterial coverage.

TobraDex (tobramycin 0.3% / dexamethasone 0.1%): the most widely prescribed combination. Dexamethasone provides strong anti-inflammatory effect but is associated with a higher risk of IOP elevation, especially with courses longer than 10 days or in known steroid responders. Available as suspension and ointment. TobraDex ST uses a smaller drop size with xanthan gum to increase contact time at a lower dexamethasone concentration (0.05%).
Zylet (tobramycin 0.3% / loteprednol 0.5%): uses an ester-based steroid that is rapidly metabolized and generally has a more favorable average IOP profile than dexamethasone. Still requires monitoring, but can be a better choice when a longer course is anticipated or when IOP history is a concern.
Maxitrol (neomycin / polymyxin B / dexamethasone 0.1%): provides broader gram-negative coverage from the polymyxin B component. However, neomycin carries a meaningfully higher risk of contact hypersensitivity. Available as suspension and ointment.
Pred-G (gentamicin 0.3% / prednisolone 1%): pairs an aminoglycoside with prednisolone. Less commonly used than tobramycin-based products but still available. Prednisolone has a different IOP risk profile than dexamethasone.

Generic tobramycin/dexamethasone is widely available and typically far less expensive than branded products. When cost is a factor and the clinical picture fits, generics are a practical first choice.

When to avoid combination drops

Fixed antibiotic-steroid combinations are generally avoided when any of the following are present or strongly suspected:

Suspected herpetic keratitis such as a dendrite or geographic ulcer
Fungal or atypical keratitis on the differential
Large or central epithelial defect of uncertain cause
Progressive stromal thinning or concern for impending perforation

Steroids suppress host immune response and can delay epithelial healing, which can worsen unrecognized viral or fungal disease. The pivotal safety question is whether the epithelium is intact. When it is, the intact epithelium itself provides a barrier against opportunistic infection, and a combination or standalone steroid is generally safe with appropriate follow-up. When it is not, or when the diagnosis is uncertain, start with a standalone antibiotic, arrange short-interval follow-up, and add steroid only when the clinical picture is clear.

IOP monitoring and follow-up

Any topical steroid, including those in combination products, can raise intraocular pressure. The risk increases with duration of use, steroid potency, and individual susceptibility. Dexamethasone-based products (TobraDex, Maxitrol) tend to carry higher IOP risk than loteprednol-based products (Zylet), but no steroid is entirely free of this risk. When prescribing any combination drop, plan follow-up that includes IOP measurement, especially if the course extends beyond 7 to 10 days. For known steroid responders, consider loteprednol-based combinations or standalone therapy where the steroid can be tapered independently of the antibiotic.

Antibiotic Steroid Combination Drops

Brand	Generic	Dosing	Amount	Ages	Pregnancy	Mechanism
Blephamide Generic	sulfacetamide 10%prednisolone acetate 0.2%	qid	5/10ml (gtt)3.5g (ung)	>6 years	C	sulfonamidecorticosteroid
Maxitrol Generic	neomycin 0.35%polymyxin bdexamethasone 0.1%	tid-qid	5mL (gtt)3.5g (ung)	>2 years	C	aminoglycosidepolymyxincorticosteroid
Tobradex Generic	tobramycin 0.3%dexamethasone 0.1%	tid-qid (gtt)tid (ung)	2.5/5/10mL (gtt)3.5g (ung)	>2 years	C	aminoglycosidecorticosteroid
Tobradex ST	tobramycin 0.3%dexamethasone 0.05%	q4h	2.5/5/10mL	>2 years	C	aminoglycosidecorticosteroid
Zylet	tobramycin 0.3%loteprednol etabonate 0.5%	q4h	2.5/5/10mL	>6 years	C	aminoglycosidecorticosteroid

Antibiotic-Steroid Combination FAQs

What is the difference between TobraDex and Zylet?: Both contain tobramycin 0.3% as the antibiotic. The difference is the steroid: TobraDex uses dexamethasone 0.1%, a more potent anti-inflammatory with a higher risk of IOP elevation. Zylet uses loteprednol 0.5%, an ester steroid that is rapidly metabolized and generally has a more favorable IOP profile. Zylet may be preferred when a longer course is anticipated or when the patient has a history of steroid response. Both still require IOP monitoring.
What is Maxitrol and when is it used?: Maxitrol contains neomycin, polymyxin B, and dexamethasone 0.1%. The polymyxin B adds gram-negative coverage beyond what tobramycin alone provides. It is used for external infections with an inflammatory component and is available as both drops and ointment. The main drawback is that neomycin has a meaningfully higher rate of contact hypersensitivity than tobramycin. If worsening itching, lid eczema, or periocular redness develops after several days, consider neomycin allergy rather than treatment failure.
Should combination drops be used for corneal ulcers?: For suspected microbial keratitis, initial management is typically steroid-sparing. Start intensive standalone antibiotic therapy first. Consider adding a steroid only after there is clear clinical improvement, the epithelium is healing, and herpetic or fungal disease has been reasonably excluded. Specialist input is often appropriate for central, large, or culture-positive ulcers. Introducing steroid too early can worsen some infections and increase the risk of stromal thinning or perforation.
Do antibiotic-steroid combination drops raise eye pressure?: Yes, any topical steroid can raise intraocular pressure. The risk is higher with dexamethasone-based products (TobraDex, Maxitrol) than with loteprednol-based products (Zylet), though no steroid is entirely risk-free. IOP elevation is more likely with courses longer than 7 to 10 days and in patients with a history of steroid response. Plan follow-up that includes IOP measurement whenever prescribing a combination drop, and consider loteprednol-based options for longer courses or steroid responders.
When should I use a standalone antibiotic vs a combination drop?: Use a standalone antibiotic when the primary concern is infection without significant inflammation, when the diagnosis is uncertain, or when the epithelium is compromised and you want to avoid steroid exposure until the picture is clear. Use a combination drop when both antibacterial coverage and inflammation control are needed simultaneously and the etiology is clear, such as staphylococcal blepharoconjunctivitis, marginal keratitis, or post-surgical prophylaxis. If the main need is anti-inflammatory control without infection concern, a standalone steroid is more appropriate.
What follow-up is appropriate when starting a combination drop?: Follow-up should match risk. For higher-risk presentations, contact lens related inflammation, or any case with corneal staining, short-interval follow-up (1 to 3 days) is appropriate to confirm improvement and ensure there is no evolving keratitis. For post-surgical use with a clean exam, follow-up within 1 week is typical. If the patient is not clearly improving, reassess the diagnosis, consider culture or referral when indicated, and avoid extending steroid exposure without a clear reason.
Is there a generic for TobraDex?: Yes. Generic tobramycin/dexamethasone ophthalmic suspension is widely available and typically costs significantly less than branded TobraDex. It contains the same active ingredients at the same concentrations. When the clinical picture fits and cost is a factor, generic tobramycin/dexamethasone is a practical first choice. Note that TobraDex ST (lower dexamethasone concentration with xanthan gum) does not currently have a direct generic equivalent.