Besifloxacin: What It Is, How It Works, and When It's Used

When your eye gets red, swollen, or starts leaking gunk, it’s often not just irritation—it’s a besifloxacin, a prescription antibiotic eye drop designed to kill bacteria causing eye infections. Also known as a fluoroquinolone antibiotic, it’s one of the most targeted treatments for bacterial conjunctivitis and other eye infections that don’t clear up on their own. Unlike oral antibiotics that flood your whole body, besifloxacin works right where it’s needed: on the surface of your eye. It stops bacteria from copying their DNA, which shuts down their ability to multiply and spread. That’s why doctors reach for it when an infection is stubborn, worsening, or showing up after surgery or injury.

Besifloxacin doesn’t treat viruses, fungi, or allergies—only bacteria. That’s why it’s not a cure-all. If your eye is itchy and watery from pollen, this won’t help. But if your eyelids are stuck shut in the morning, your vision is blurry, or your eye feels like it’s full of sand, and a doctor confirms it’s bacterial, besifloxacin is often the first-line choice. It’s especially common after cataract surgery, corneal abrasions, or when contact lens wearers develop infections. Compared to older eye drops like ciprofloxacin or ofloxacin, besifloxacin stays in the eye longer, which means fewer doses per day and better coverage. It’s also less likely to trigger resistance because it’s designed specifically for the eye’s unique environment.

What you won’t find in most ads is that besifloxacin isn’t something you buy over the counter. You need a prescription, and your doctor will check for signs of deeper infection before prescribing it. It’s not for kids under 1 year old, and if you’re allergic to other fluoroquinolones like cipro or levaquin, you’ll likely need something else. Side effects are usually mild—stinging, blurry vision for a few minutes—but if your eye gets worse after using it, stop and call your doctor. This isn’t a drug to guess with. The bacterial eye infections, infections caused by bacteria like Staphylococcus or Streptococcus that affect the conjunctiva or cornea it treats can turn serious fast if ignored.

What’s interesting is how besifloxacin fits into the bigger picture of eye care. It’s part of a shift away from broad-spectrum treatments toward precision medicine—even for something as simple as a red eye. You’ll see this same thinking in the posts below: comparisons between different antibiotics, when to skip pills and use drops instead, and how to avoid making infections worse by using the wrong treatment. Whether you’re dealing with a recent eye injury, recurring infections, or just trying to understand why your doctor chose this specific drop, the articles here give you real, practical insight—not just textbook definitions. No fluff. Just what works, what doesn’t, and what to watch for.