Levofloxacin is a fluoroquinolone (flor-o-KWIN-o-lone) antibiotic that fights bacteria in the body. Levofloxacin is used to treat different types of bacterial infections. Levofloxacin is also used to treat people who have been exposed to anthrax or certain types of plague.

Fluoroquinolone antibiotics can cause serious or disabling side effects that may not be reversible. Levofloxacin should be used only for infections that cannot be treated with a safer antibiotic.

Levofloxacin may also be used for purposes not listed in this medication guide.

Levofloxacin can cause serious side effects, including tendon problems, nerve damage, serious mood or behavior changes, or low blood sugar.

Stop using this medicine and call your doctor at once if you have symptoms such as: headache, hunger, irritability, numbness, tingling, burning pain, confusion, agitation, paranoia, problems with memory or concentration, thoughts of suicide, or sudden pain or movement problems in any of your joints.

In rare cases, levofloxacin may cause damage to your aorta, which could lead to dangerous bleeding or death. Get emergency medical help if you have severe and constant pain in your chest, stomach, or back.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Levofloxacin injection is given as an infusion into a vein. A healthcare provider will give your first dose and may teach you how to properly use the medication by yourself.

Read and carefully follow any Instructions for Use provided with your medicine. Do not use levofloxacin injection if you don't understand all instructions for proper use. Ask your doctor or pharmacist if you have questions.

Levofloxacin must be injected slowly, over at least 60 minutes.

Levofloxacin is usually given for up to 14 days. Some infections may need to be treated for 4 to 8 weeks. Anthrax exposure is usually treated for 60 days.

Follow your doctor's dosing instructions very carefully.

Drink extra fluids to keep your kidneys working properly while using this medicine.

Use this medicine for the full prescribed length of time, even if your symptoms quickly improve. Skipping doses can increase your risk of infection that is resistant to medication. Levofloxacin injection will not treat a viral infection such as the flu or a common cold.

This medicine may affect a drug-screening urine test and you may have false results. Tell the laboratory staff that you use levofloxacin.

Store at room temperature away from moisture, heat, and light. Do not freeze.

You should not use this medicine if you are allergic to levofloxacin or other fluoroquinolones (ciprofloxacin, gemifloxacin, moxifloxacin, ofloxacin, norfloxacin, and others).

Levofloxacin may cause swelling or tearing of a tendon (the fiber that connects bones to muscles in the body), especially in the Achilles' tendon of the heel. This can happen during treatment or up to several months after you stop using levofloxacin. Tendon problems may be more likely in certain people (children and older adults, or people who use steroid medicine or have had an organ transplant).

Tell your doctor if you have ever had:

• tendon problems, bone problems, arthritis or other joint problems (especially in children);

• blood circulation problems, aneurysm, narrowing or hardening of the arteries;

• heart problems, high blood pressure;

• a genetic disease such as Marfan syndrome or Ehler's-Danlos syndrome;

• diabetes;

• a muscle or nerve disorder, such as myasthenia gravis;

• liver disease;

• kidney disease;

• seizures or epilepsy;

• a head injury or brain tumor;

• long QT syndrome (in you or a family member); or

• low levels of potassium in your blood (hypokalemia).

It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant.

You should not breast-feed while using this medicine.

Call your doctor for instructions if you miss a dose of levofloxacin injection.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Avoid driving or hazardous activity until you know how this medicine will affect you. Your reactions could be impaired.

Antibiotic medicines can cause diarrhea, which may be a sign of a new infection. If you have diarrhea that is watery or bloody, call your doctor before using anti-diarrhea medicine.

Levofloxacin could make you sunburn more easily. Avoid sunlight or tanning beds. Wear protective clothing and use sunscreen (SPF 30 or higher) when you are outdoors. Tell your doctor if you have severe burning, redness, itching, rash, or swelling after being in the sun.

Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Levofloxacin can cause serious side effects, including tendon problems, side effects on your nerves (which may cause permanent nerve damage), serious mood or behavior changes (after just one dose), or low blood sugar (which can lead to coma).

Stop using this medicine and call your doctor at once if you have:

• low blood sugar--headache, hunger, sweating, irritability, dizziness, nausea, fast heart rate, or feeling anxious or shaky;

• nerve symptoms in your hands, arms, legs, or feet--numbness, weakness, tingling, burning pain;

• serious mood or behavior changes--nervousness, confusion, agitation, paranoia, hallucinations, memory problems, trouble concentrating, thoughts of suicide; or

• signs of tendon rupture--sudden pain, swelling, bruising, tenderness, stiffness, movement problems, or a snapping or popping sound in any of your joints (rest the joint until you receive medical care or instructions).

In rare cases, levofloxacin may cause damage to your aorta, the main blood artery of the body. This could lead to dangerous bleeding or death. Get emergency medical help if you have severe and constant pain in your chest, stomach, or back.

Also, stop using levofloxacin and call your doctor at once if you have:

• severe stomach pain, diarrhea that is watery or bloody;

• fast or pounding heartbeats, fluttering in your chest, shortness of breath, and sudden dizziness (like you might pass out);

• the first sign of any skin rash, no matter how mild;

• a seizure (convulsions);

• muscle weakness or trouble breathing;

• liver problems--upper stomach pain, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes); or

• increased pressure inside the skull--severe headaches, ringing in your ears, dizziness, nausea, vision problems, pain behind your eyes.

Common side effects of Levaquin may include:

• nausea, constipation, diarrhea;

• dizziness;

• headache; or

• sleep problems (insomnia).

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Tell your doctor about all your other medicines, especially:

• theophylline;

• a blood thinner (warfarin, Coumadin, Jantoven);

• a diuretic or "water pill";

• heart rhythm medication;

• insulin or oral diabetes medicine (check your blood sugar regularly);

• medicine to treat depression or mental illness;

• steroid medicine (such as prednisone); or

• NSAIDs (nonsteroidal anti-inflammatory drugs)--aspirin, ibuprofen (Advil, Motrin), naproxen (Aleve), celecoxib, diclofenac, indomethacin, meloxicam, and others.

This list is not complete. Other drugs may affect levofloxacin, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.