8 Levofloxacin Interactions You Should Know About

Levofloxacin is a fluoroquinolone antibiotic (“quinolone”) used to treat many bacterial infections. Your healthcare provider may prescribe it if there’s a hard-to-treat infection in your lungs, urinary tract, or skin — among other parts of your body. Quinolones such as levofloxacin take the fight straight to the bacteria and interfere with important enzymes (proteins) that help them grow and multiply.

At the same time, levofloxacin may interact with other medications and supplements you take. Some interactions can affect how levofloxacin works. Others can raise your risk of side effects, such as low blood glucose (sugar). Levofloxacin can also cause “false positive” results on urine drug tests.

Below, we’ll review eight of the most important levofloxacin interactions to watch out for and how to manage them. Keep in mind this list doesn’t include all medications and supplements that can interact with levofloxacin.

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1. Antacids and multivitamins containing magnesium, aluminum, iron, or zinc

Certain antacids that contain magnesium or aluminum, such as Mylanta and Milk of Magnesia, can interact with levofloxacin. Multivitamins and supplements containing iron and zinc can also interact with the antibiotic.

When taken together, these products attach to levofloxacin in your gut. This causes your body to absorb less of the antibiotic. This means that levofloxacin won’t work as well at fighting infections.

You can still take products containing magnesium, aluminum, iron, or zinc while taking levofloxacin. But it’s recommended to separate levofloxacin from these supplements to prevent this interaction. It’s best to take any products that contain these substances at least 2 hours before or 2 hours after taking levofloxacin. This will allow your body to absorb levofloxacin better.

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2. Sucralfate

Sucralfate (Carafate) is a prescription medication that coats your stomach and intestines to help ulcers heal. And like certain antacids, it contains aluminum. When taken with levofloxacin, sucralfate can bind to it and lower its absorption. This can prevent levofloxacin from working as well, potentially leading to an undertreated infection.

To avoid this interaction, you’ll want to take sucralfate at least 2 hours before or 2 hours after taking levofloxacin.

3. Diabetes medications like insulin

When taken on its own, levofloxacin can cause low blood glucose levels — also known as hypoglycemia. If you have diabetes and combine levofloxacin with insulin or insulin-releasing medications, such as glyburide (Glynase), your blood glucose could drop too low. This is because the medications can have additive effects with each other.

If you take insulin or an oral diabetes medication and you’re prescribed levofloxacin, it’s a good idea to check your blood glucose more often. And keep an eye out for hypoglycemia symptoms, such as shakiness, increased hunger, and anxiety.

As a precaution, do your best to always have a fast-acting sugar source on hand to raise your blood glucose when needed. Being prepared is the best way to avoid emergency situations. But be sure to contact your provider if you experience severe or frequent episodes of hypoglycemia.

4. Heart rhythm medications like amiodarone

Although rare, levofloxacin can affect your heartbeat. There have been reports of QT prolongation, a dangerous condition that lengthens the time it takes your heart to contract and relax. It’s like a hiccup in your heartbeat, which can sometimes lead to abnormal heart rhythms or arrhythmias.

The risk is higher if you take levofloxacin together with other heart rhythm medications, such as amiodarone (Pacerone) or propafenone (Rythmol). The risk is also higher if you’re considered an older adult, have a history of long QT syndrome, or your potassium levels are too low.

It’s best to avoid combining levofloxacin with heart rhythm medications. You should also avoid taking levofloxacin if you have a history of abnormal heartbeats. A different antibiotic would be a safer choice in cases like these.

QT prolongation may not always cause noticeable symptoms. But if you feel like you’re about to faint or experience a fast or fluttering heartbeat, get medical attention right away. 

5. NSAIDs like Advil

Although rare, levofloxacin can cause or contribute to seizures. It’s more common in older adults and those who have a history of seizures, kidney disease, or liver problems.

Other rare reports of levofloxacin-induced seizures were reported by people taking nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil, Motrin) or diclofenac (Cambia). 

Before starting levofloxacin, tell your healthcare provider if you’re taking an NSAID. They may recommend closer monitoring for seizures or switch you to a different antibiotic altogether. And if you or someone you care about experiences a seizure while taking levofloxacin, call 911 or seek medical help right away.

6. Warfarin

Warfarin (Coumadin, Jantoven) is a blood thinner used to prevent and treat blood clots.

Levofloxacin can block your liver from breaking down warfarin, enhancing its effects. This means you have a higher risk of experiencing warfarin side effects. Keep an eye out for symptoms like dark or bloody stools, bleeding from your gums, or easy bruising.

Tell your healthcare provider if you plan to start taking levofloxacin while you’re taking warfarin. They may want to monitor your blood work more often while taking this medication combination. Or they may switch you to a different antibiotic.

7. Theophylline

Theophylline (Theo-24, Elixophyllin) treats asthma and chronic obstructive pulmonary disease (COPD). It works by relaxing the muscles in your lungs so you can breathe easier. And while levofloxacin isn’t believed to affect the absorption and clearance of theophylline, other quinolones have been reported to do so. 

For instance, ciprofloxacin (Cipro) can block the breakdown and clearance of theophylline. This may cause high levels of theophylline in your body, which can worsen side effects such as nausea, vomiting, and headaches that won’t go away. Serious side effects include trouble breathing, increased heart rate, and seizures. 

If you take theophylline and levofloxacin together, your healthcare provider will monitor your theophylline blood levels more closely as a precaution. And they may lower your theophylline dose if your levels jump too high. Call 911 or seek emergency medical care if you experience trouble breathing or seizures.

8. Urine tests

Interactions between medications, supplements, and foods aren’t the only types of interaction. Levofloxacin may also affect lab tests that examine your urine. 

Levofloxacin can cause a false-positive for opioids such as oxycodone (Roxicodone, OxyContin) on certain urine tests. This means that levofloxacin can “trick” a test into showing that opiates are in your urine when they aren’t.

If you’re taking levofloxacin and think you’ve had a false positive result on a urine drug test, contact your healthcare provider. They may be able to administer a different test that’s more accurate and specific.

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Written by:

Nikki Javit, PharmD

Nikki Javit, PharmD, is a clinical pharmacist with certifications in international travel medicine, immunization delivery, and pharmacogenomics. She received her bachelor’s of science in biology from Indiana University Bloomington and her doctor of pharmacy degree from Butler University.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Austin Ulrich, PharmD, BCACP

Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. In his early career, he provided direct patient care in a variety of settings, including hospital and community pharmacies, and in a primary care clinic as a clinical pharmacist.

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