Levofloxacin 500 mg is a prescription antibiotic used to treat a range of bacterial infections, most commonly pneumonia, skin infections, urinary tract infections, sinus infections, and chronic prostatitis. It belongs to a class of antibiotics called fluoroquinolones, which work by blocking an enzyme bacteria need to copy their DNA. Without that enzyme, bacterial cells can’t grow or reproduce, and the infection clears.
The 500 mg tablet is one of several available strengths, and it’s the standard dose for several common infections in adults. Here’s what it treats, how it works in practice, and what you should know before taking it.
Infections Treated With Levofloxacin
Levofloxacin 500 mg is approved for use in adults (18 and older) for a broad set of bacterial infections. The most common reason it’s prescribed is community-acquired pneumonia, the type of lung infection you pick up outside of a hospital. For pneumonia, a typical course runs 7 to 14 days at 500 mg once daily. It’s effective against many of the bacteria that cause pneumonia, including strains of Streptococcus pneumoniae that have developed resistance to multiple other antibiotics.
It’s also used for hospital-acquired pneumonia, which tends to involve harder-to-treat bacteria. For these more serious cases, a higher 750 mg dose is typically prescribed instead.
Other approved uses at various doses include:
- Complicated urinary tract infections and kidney infections (acute pyelonephritis): Treatment lasts 5 to 10 days depending on the specific bacteria involved and the dose chosen.
- Skin infections: Both mild cases like cellulitis, abscesses, and wound infections, and more complicated skin infections that have spread deeper.
- Chronic bacterial prostatitis: A persistent prostate infection that can be difficult to clear with other antibiotics. Levofloxacin penetrates prostate tissue well, which is why it’s commonly chosen for this condition.
- Anthrax (post-exposure): Used as a preventive measure after someone has been exposed to inhaled anthrax spores. This is one of the few approved uses in children as young as 6 months.
- Plague: Both for treatment and prevention of pneumonic and blood-borne plague, also approved for children 6 months and older.
Levofloxacin was previously a go-to option for sinus infections and bronchitis flare-ups, but prescribing guidelines have shifted. The FDA has warned that for conditions with other effective treatment options, the serious risks of fluoroquinolones may outweigh their benefits. Your doctor is more likely to try a different antibiotic first for a straightforward sinus infection.
How Levofloxacin Works
Levofloxacin passes through bacterial cell walls and targets an enzyme called DNA gyrase. This enzyme is essential for bacteria to unwind and copy their DNA during cell division. By shutting it down, the drug stops bacteria from replicating entirely. It’s bactericidal, meaning it kills bacteria rather than simply slowing their growth.
One practical advantage: levofloxacin is absorbed well from the gut, so the oral tablet delivers blood levels comparable to an IV infusion. That means patients who start on an IV in the hospital can often switch to the oral tablet to finish their course at home. The drug stays active in the body for 6 to 8 hours, which is long enough to allow once-daily dosing for most infections.
Taking It Correctly
Levofloxacin is taken once a day, with or without food, and you should drink plenty of fluids while on it. The most important practical detail: common supplements and over-the-counter products can block the drug from being absorbed properly. Anything containing calcium, magnesium, iron, zinc, or aluminum (including most antacids, multivitamins, and mineral supplements) will bind to levofloxacin in your stomach and prevent it from reaching your bloodstream.
If you take any of these products, the timing rule is straightforward. Take levofloxacin at least 2 hours before or 4 to 6 hours after the supplement or antacid. Missing this window can make the antibiotic significantly less effective.
Finish the entire prescribed course even if you feel better partway through. Stopping early increases the chance the infection returns, potentially with bacteria that are harder to treat the second time around.
Serious Risks and Warnings
Fluoroquinolones, including levofloxacin, carry several FDA boxed warnings, the most serious type of safety alert. The first was added in 2008 for an increased risk of tendon inflammation and tendon rupture, particularly the Achilles tendon. This risk is highest in people over 60, those taking corticosteroids, and organ transplant recipients. If you notice sudden pain, swelling, or a popping sensation in a tendon, stop the medication and contact your doctor immediately.
Additional warnings cover nerve damage (peripheral neuropathy), which can cause tingling, numbness, or burning in the hands and feet, sometimes lasting long after the drug is stopped. There are also concerns about effects on mood and mental health, including confusion, agitation, and in rare cases, hallucinations. The FDA has noted a possible association with aortic aneurysms, particularly in older adults.
People with myasthenia gravis, a condition that causes muscle weakness, need special caution. The FDA added a warning in 2011 about fluoroquinolones worsening symptoms. Research from the Cleveland Clinic found that patients most at risk were those who had been hospitalized or visited an emergency department for myasthenia gravis within the prior six months (with roughly 13 times the odds of a flare-up compared to more stable patients). Women with the condition also faced higher risk. For patients whose myasthenia gravis is stably controlled, the actual rate of flare-ups was small and not significantly different from rates seen with other common antibiotics.
Kidney Function and Dose Adjustments
Levofloxacin is cleared primarily through the kidneys. If your kidney function is reduced, the drug stays in your system longer than intended and can build up to higher-than-safe levels. For people with significantly impaired kidney function, doctors will lower the dose or space it out further. This is typically determined by a blood test measuring how well your kidneys filter waste. If you’re on dialysis, the dosing schedule is adjusted as well. Your prescriber handles this calculation, but it’s worth knowing that kidney health directly affects how this drug is managed.
Why It’s Reserved for Certain Infections
Levofloxacin is a powerful, broad-spectrum antibiotic, and that power is exactly why doctors are increasingly careful about when to use it. The FDA has recommended that fluoroquinolones be reserved for infections that have no other good treatment options, particularly when the infection is serious. For straightforward conditions like an uncomplicated urinary tract infection or a mild sinus infection, narrower-spectrum antibiotics are preferred as a first choice.
This shift isn’t because levofloxacin doesn’t work for those conditions. It does. The concern is that its side effect profile, particularly the risk of tendon, nerve, and mood-related problems, tips the risk-benefit balance when safer alternatives exist. For pneumonia, complicated UTIs, chronic prostatitis, and serious skin infections where other options have failed or aren’t suitable, levofloxacin remains an important and effective treatment.