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. 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.

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

Do not give this medicine to a child without medical advice.

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.

Use Levaquin Leva-Pak (Oral) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

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 in your eyes, skin pain, red or purple skin rash that spreads and causes 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 taking 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.

Stop taking 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;
• muscle weakness, breathing problems;
• seizure (convulsions);
• increased pressure inside the skull--severe headaches, ringing in your ears, dizziness, nausea, vision problems, pain behind your eyes; or
• liver problems--upper stomach pain, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Common side effects may include:

• nausea, constipation, diarrhea;
• headache, dizziness; or
• trouble sleeping.

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.

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.