Possible Side Effects Levaquin
The most frequently reported side effects are nausea or vomiting (1 out of every 12 persons), diarrhea (1 out 20), headache (1 out 20), and constipation (1 out of 30). Less common side effects include difficulty sleeping, dizziness, abdominal pain, rash, abdominal gas, and itching.

Drug Class and Mechanism Levaquin
Many common infections in humans are caused by single cell organisms, called bacteria. Bacteria can grow and multiply, infecting different parts of the body. Medicines that control and eradicate these bacteria are called antibiotics. Levofloxacin is an antibiotic that stops multiplication of bacteria by preventing the reproduction and repair of their genetic material (DNA). It is in a class of antibiotics, called fluoroquinolones, a class that includes ciprofloxacin (Cipro), norfloxacin (Noroxin), ofloxacin (Floxin), trovafloxacin (Trovan), and lomefloxacin (Maxaquin). Levofloxacin was approved by the FDA in 1996.

More InformationLevaquin here
If you experience any of the following serious side effects, stop taking levofloxacin and seek emergency medical attention or contact your doctor immediately: an allergic reaction (difficulty breathing; closing of the throat; swelling of the lips, tongue, or face; or hives); seizures; confusion or hallucinations; irregular heartbeats, chest pain, or fainting; liver damage (yellowing of the skin or eyes, nausea, abdominal pain or discomfort, unusual bleeding or bruising, severe fatigue); or muscle or joint pain.If you experience any of the following less serious side effects, continue taking levofloxacin and talk to your doctor:nausea, vomiting, diarrhea, or constipation; headache or lightheadedness; drowsiness; insomnia; ringing in the ears; or increased sensitivity of the skin to sunlight.Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.