Fluoroquinolone Antibiotics

Fluoroquinolone antibiotics like Cipro, Avelox and Levaquin are used to treat many different types of infections, but they may also double the risk of life-threatening side effects like aortic aneurysm or aortic dissection. Manufacturers of fluoroquinolones may be facing lawsuits for deadly side effects like hemorrhage, aortic aneurysm, aortic dissection, or other injuries.

Sign up for our newsletter to get updates on drugs & medical devices

If you would like to sign up for our newsletter click the button below.

Sign Up For Newsletter

Why Are There Fluoroquinolone Lawsuits?

Different Fluoroquinolone drugs are under investigation for causing long-lasting or permanent side effects in patients. Additionally, the companies that manufacture them have been accused of failing to adequately warn doctors of the risks associated with these medications, preventing them from accurately warning patients.

Why Have Plaintiffs Filed Fluoroquinolone Lawsuits?

The plaintiffs claimed that the use of fluoroquinolones has left them with serious and sometimes permanent side effects. These side effects range from aortic dissections and aortic aneurysms to tendon ruptures. The plaintiffs were not made aware of these risks before taking the fluoroquinolones and claimed that the manufacturers were aware of these serious side effects and failed to properly warn them. 

Which Fluoroquinolones Are Associated With Lawsuits?

Cipro (ciprofloxacin), Avelox (moxifloxacin), and Levaquin (levofloxacin) are brands of fluoroquinolones most often named in lawsuits. They have also been the most widely used antibiotics in the U.S.

What Fluoroquinolone Settlements Have There Been?

There are no publicized verdicts or settlements for aortic injury lawsuits. 

In November 2010, the first bellwether trial was tried against Ortho-McNeil Pharmaceutical Inc., resulting in a jury verdict in favor of the plaintiff. These lawsuits claimed that fluoroquinolones were associated with damaging the peripheral nerves. The jury awarded the plaintiff $700,000 in compensatory damages, which was later reduced to $630,000. The jury also awarded punitive damages in the amount of $1,115,000. 

Lawsuits claiming that fluoroquinolones cause peripheral neuropathy were settled confidentially, with the settlement amounts being undisclosed. 

What Fluoroquinolone Lawsuits Are There?

The federal court scheduled bellwether trials in 2018 and 2019. There were a total of 10 cases, eight Avelox cases, and two Cipro cases. There have been no updates on these trials as of November 2022.

About 2,049 total actions were filed under the MDL. Only 10 remained pending as of March 2017. The U.S. Judicial Panel on Multidistrict Litigation officially closed the MDL in July 2017.

As of 2023, there are no new lawsuits associated with fluoroquinolones. 

What Are Fluoroquinolones?

Fluoroquinolones are a family of broad-spectrum antibacterial agents used to treat respiratory and urinary tract infections. 

How Do Fluoroquinolones Work?

Fluoroquinolones work by inhibiting type II DNA topoisomerases that are required for the synthesis of bacterial mRNAs and DNA replication. Essentially, they prevent the bacteria from reproducing and spreading throughout the body. 

What Is Cipro?

Cipro (Ciprofloxacin) is a second-generation fluoroquinolone that is used to treat mild to moderate urinary and respiratory tract infections. It works in the same way that Avelox does, preventing the DNA of the bacteria from replicating. 

What Is Levaquin?

Levaquin (Levofloxacin) is the L-enantiomer of ofloxacin and is considered a third-generation fluoroquinolone. This fluoroquinolone works in the same way as the other two fluoroquinolones, Cipro and Avelox, by inhibiting the replication of the bacteria’s DNA. 

What Is Avelox?

Avelox (Moxifloxacin) is a fourth-generation fluoroquinolone with expanded activity against gram-positive bacteria including multidrug-resistant strains of strep. Like other fluoroquinolones, moxifloxacin is active against a wide range of aerobic gram-positive and gram-negative organisms. 

They’re believed to act by inhibiting bacterial DNA gyrase and topoisomerase IV which are required for the bacteria’s DNA to replicate. 

Who Created Fluoroquinolones?

Nalidixic acid was discovered by George Lesher and coworkers in a distillate during an attempt at chloroquine synthesis. Nalidixic acid is thus considered to be the predecessor of all members of the quinolone family, including the second, third, and fourth generations commonly known as fluoroquinolones.

Today, many corporations produce fluoroquinolones. Some of these companies include: 

  • Bayer Healthcare Pharmaceuticals, Inc.
  • Johnson & Johnson
  • Janssen Research & Development LLC
  • Schering-Plough Corporation
  • Bayer Corporation

What Are Fluoroquinolones Prescribed To Treat?

There are a wide range of uses for fluoroquinolones.

Some of the uses have included: 

  • Urinary tract infection
  • Sinusitis
  • Pneumonia
  • Bronchitis
  • Skin and soft tissue infection
  • Sexually transmitted infection
  • Bone and joint infection
  • Infectious diarrhea
  • Hospital-acquired infections

What Do Fluoroquinolones Treat?

Fluoroquinolones are used for the treatment of several bacterial infections. 

What Is a Respiratory Infection?

Respiratory tract infections (RTIs) are infections of parts of the body involved in breathing such as the sinuses, throat, airways, or lungs. 

What Are the Symptoms of a Respiratory Infection?

Symptoms of an RTI include: 

  • Coughing
  • Sneezing
  • Stuffy or runny nose
  • Sore throat
  • Headaches
  • Muscle aches
  • Breathlessness, tight chest, or wheezing
  • High temperature

What Causes a Respiratory Infection?

RTIs are often spread in the coughs and sneezes of someone with an infection.

What Are the Risk Factors of a Respiratory Infection?

Risk factors for chronic RTIs include tobacco smoking (and secondhand smoke), air pollution, and allergens.

What Is a Urinary Tract Infection?

A UTI is an infection in any part of the urinary system, including the kidneys, ureters, bladder, and urethra. 

What Are the Symptoms of a Urinary Tract Infection?

UTIs don’t always cause symptoms.

When they do, they may include:

  • A strong urge to urinate that doesn’t go away
  • A burning feeling when urinating
  • Urinating often, and passing small amounts of urine
  • Urine that looks cloudy
  • Urine that appears red, bright pink, or brown (signs of blood in the urine)
  • Strong-smelling urine
  • Pelvic pain

What Causes a Urinary Tract Infection?

UTIs typically occur when bacteria enter the urinary tract through the urethra and begin to spread in the bladder. The bacteria take hold and grow into a full-blown infection. 

What Are the Risk Factors of a Urinary Tract Infection?

UTIs are common in women.

Risk factors for UTIs that are specific to women include: 

  • Female anatomy
  • Sexual activity
  • Certain types of birth control
  • Menopause

Other risk factors for UTIs include:

  • Urinary tract problems
  • Blockages in the urinary tract
  • A suppressed immune system
  • Catheter use
  • A recent urinary procedure

What Are the Side Effects of Fluoroquinolones?

Like all medications, fluoroquinolones may cause side effects, most of which are mild to moderate but others may be more severe. Additionally, specific fluoroquinolones will have their own list of side effects. 

What Are the Common Side Effects of Fluoroquinolones?

Some of the most common side effects of fluoroquinolones are: 

  • Nausea and vomiting
  • Headache
  • Itching 
  • Vaginitis

What Are the Adverse Side Effects of Fluoroquinolones?

More serious side effects of fluoroquinolones include: 

  • Allergic symptoms of rash, itching, facial swelling, or difficulty breathing
  • Watery diarrhea
  • Tingling or unusual pain
  • Changes in skin, urine, or stool color
  • Fast or pounding heartbeat
  • Severe headache, dizziness, or fainting
  • Severe nervousness or anxiety 
  • Hallucinations, confusion, or unusual behavior
  • Seizures
  • Sudden pain or popping of joints
  • Swelling or fluid collection

Any of these symptoms are serious and should be reported to your doctor immediately. 

What Are the FDA’s Warnings About Fluoroquinolones?

In 2008, the U.S. Food and Drug Administration issued a” black box warning” regarding the dangers of fluoroquinolones and tendon rupture. The FDA began requiring that manufacturers print information about the risk of tendon damage in a “black box” at the top of prescribing information for all fluoroquinolones.

In 2015, the FDA reviewed reports of tendon rupture, nerve damage, and cardiac events associated with fluoroquinolone use and determined that medications should not be used as a first choice for uncomplicated urinary tract infections, sinusitis, and bronchitis.

In June 2016, the prescribing information for all fluoroquinolones was changed to state that the medications should not be used if other treatments were available and to discontinue use if serious side effects occurred.

What Is a Black Box Warning?

A black box warning (also called a boxed warning) is the highest safety-related warning the Food and Drug Administration assigns. These warnings can be added, updated, and removed depending on what the FDA deems necessary. Boxed warnings are specifically used to warn consumers of the major risks of a certain drug.

What Are Aortic Aneurysm and Aortic Dissection?

As part of the way fluoroquinolones work, they may affect the formation of collagen and interfere with cells that make and repair cartilage. This leads to weakened cartilage. 

The aorta is the largest blood vessel in the circulatory system and carries oxygenated blood from the heart to the body tissues. It is a rigid vessel that is formed and supported by a collagen structure. When collagen is weakened by fluoroquinolone use, the aorta wall may thin and bulge or tear. When a bulge ruptures, blood may rush into the abdominal space. This is known as Aortic Aneurysm.

An aortic dissection is a condition where a tear occurs in the inner layer of the aorta. Blood then rushes through the tear, causing the inner and middle of the layers to split. This can become deadly if the blood goes through the outside aortic wall. 

What Is Aortic Aneurysm?

An aortic aneurysm is a balloon-like bulge in the aorta. This can lead to an aortic dissection or tear. Many factors can put patients at risk for aortic aneurysms such as smoking, high blood pressure, and atherosclerosis (hardened arteries). 

What Is Tendon Rupture?

Studies indicated that fluoroquinolones are toxic to collagen, which makes up most of the cartilage in large tendons. They may also interfere with cartilage repair by inhibiting enzymes or killing some of the cells needed to make new cartilage, known as chondrocytes.

Tendon ruptures are injuries to the soft tissues that connect muscles and joints. When tendon ruptures happen, patients experience extreme pain, and swelling, and can sometimes hear a pop when the tissue tears. 

Are Fluoroquinolones Still on the Market?

Many fluoroquinolones remain FDA-approved but some manufacturers have voluntarily stopped producing or selling the drugs such as makers of Avelox and Levaquin. Cipro is one fluoroquinolone which is still available on the market in 2023. The black-box labels recommend that fluoroquinolone use should be reserved for patients who have no other alternative treatment options for bacterial bronchitis or acute bacterial sinusitis. Fluoroquinolones are not approved for use in children and should be limited to patients who are at greater risk for cartilage disruption, such as the elderly.

Notwithstanding claims relating to this product, the drug/medical device remains approved by the U.S. FDA. 


  1. Aortic Aneurysm | (2021, September 27). Centers for Disease Control and Prevention.,to%20leak%20in%20between%20them.
  2. Aortic dissection – Symptoms & causes – Mayo Clinic. (2021, August 6). Mayo Clinic.
  3. Delong, C. (2023, February 11). Black Box Warning. StatPearls – NCBI Bookshelf.
  4. Drugwatch. (2022a, November 4). Cipro, Levaquin & Avelox Lawsuits | Fluoroquinolone Claims.,not%20inform%20and%20instruct%20patients.
  5. Fluoroquinolone | District of Minnesota | United States District Court. (n.d.).,developed%2C%20manufacture%20and%20market%20fluoroquinolones.
  6. National Institute of Diabetes and Digestive and Kidney Diseases. (2020a, February 28). Ciprofloxacin. LiverTox – NCBI Bookshelf.
  7. National Institute of Diabetes and Digestive and Kidney Diseases. (2020b, March 10). Levofloxacin. LiverTox – NCBI Bookshelf.
  8. National Institute of Diabetes and Digestive and Kidney Diseases. (2020c, March 10). Moxifloxacin. LiverTox – NCBI Bookshelf.
  9. PharmaTimes. (n.d.). Abbott settles TriCor lawsuits for $184 million. PharmaTimes.$184_million_986337
  10. PRAC May 2023 – Restrictions on the use of fluoroquinolone antibiotics and new safety information for fluoroquinolone antibiotics and Gavreto | FAMHP. (n.d.).
  11. Research, C. F. D. E. A. (2018). FDA Drug Safety Communication: FDA updates warnings for oral and injectable fluoroquinolone antibiotics due to disabling side effects. U.S. Food And Drug Administration.
  12. Research, C. F. D. E. A. (2022). FDA Drug Safety Podcast: FDA updates warnings for oral and injectable fluoroquinolone antibiotics due to disabling side effects. U.S. Food And Drug Administration.,and%20worsening%20of%20myasthenia%20gravis.
  13. Tendon & Ligament Injury, Rupture, and Tear Treatment | UPMC. (n.d.). UPMC | Life Changing Medicine.,Cause%20extreme%20pain.
  14. Urinary tract infection (UTI) – Symptoms and causes – Mayo Clinic. (2022, September 14). Mayo Clinic.
  15. Website, N. (2023, February 24). Respiratory tract infections (RTIs).,need%20to%20see%20a%20GP.
  16. World Health Organization: WHO. (2019). Chronic respiratory diseases.