Fluoroquinolones: Safety, Risks, and Side Effects

Written by Marijke Vroomen Durning, RN
Medically Reviewed by Jabeen Begum, MD on May 01, 2025
5 min read

Fluoroquinolones are a class of antibiotics approved to treat or prevent certain types of bacterial infections. They were discovered in the 1960s, and doctors began to prescribe them in the 1970s and 80s.

“Fluoroquinolones became popular because they were effective against various common infections, ranging from urinary tract infections to pneumonia,” explains pharmacist Ivy Ge, PharmD, in San Francisco. “The pills are easy to take (often one or twice a day). Doctors appreciated how effective they were and how quickly they worked, especially when other antibiotics didn’t help.” 

Unfortunately, these antibiotics cause serious side effects in some people, and their popularity has led to too many prescriptions, resulting in bacteria becoming resistant to them.

How do fluoroquinolones work?

For bacteria to multiply, they need special enzymes to copy their DNA, which has a spiral shape. These enzymes untwist the DNA so it can make those copies. Fluoroquinolones stop the enzymes from untwisting the DNA, which means that there can’t be any copies. This prevents the bacteria from spreading.

 

First, let’s look at what fluoroquinolones shouldn’t be used for. The FDA advises against using them for the treatment of three common infections:

“Fluoroquinolones should be used for more serious or complicated infections, especially when other antibiotics won’t work or the bacteria are resistant,” Ge says. They might also be needed for people with other health problems that make treatment harder.

Doctors might prescribe fluoroquinolones to treat:

Dentists may also prescribe fluoroquinolones to treat some dental infections.

The FDA says it’s OK to use fluoroquinolones for other serious infections or for patients who have no other choice of treatment. This might include patients with allergies to other antibiotics or infections caused by hard-to-treat, resistant bacteria.

Fluoroquinolone antibiotics list

Fluoroquinolone antibiotics include:

They’re available as oral medications (taken by mouth), IV injections, ear drops, and eye drops.

When prescribing antibiotics for a bacterial infection, doctors have to keep in mind what kind of infection you have, how severe it is, and what types of medications you can take, especially if you have allergies or other health issues. These are just a few of the antibiotics your doctor might prescribe to avoid using a fluoroquinolone:

As fluoroquinolones became more widely used, doctors started to notice serious side effects in some people who took them. Some of the side effects were disabling and caused potentially permanent damage. While they don’t affect everyone, they happen often enough to cause concern.

Fluoroquinolone side effects

All medications, including fluoroquinolones, can cause side effects, some are mild and some can be quite severe. “Some uncommon but serious side effects of fluoroquinolones include tendon problems (such as tendon rupture), nerve damage (called peripheral neuropathy), mental health effects (such as confusion or mood changes), and worsening muscle weakness in people with myasthenia gravis,” Ge says. “They can also affect the heart’s rhythm in certain people and cause blood sugar disturbances.” 

“Side effects may occur within hours to weeks after starting treatment with a fluoroquinolone medicine. Some people experience side effects months after stopping fluoroquinolone treatment,” she adds. 

Other possible fluoroquinolone side effects include:

  • Nausea
  • Tremors
  • Seizures
  • Numbness or a tingling (pins and needles) in your arms or legs
  • Muscle or joint pain
  • Joint swelling
  • Anxiety
  • Depression
  • Hallucinations
  • Suicidal thoughts
  • Confusion
  • Skin rash triggered by sunlight
  • Severe diarrhea

This group of antibiotics is also a common cause of another infection called Clostridioides difficile (C. diff)-induced diarrhea.

The U.S. FDA has reported that fluoroquinolones can also cause a rare but very serious issue called aortic dissection, which is a tear or rupture of the aorta.

Based on patient reports of side effects, the FDA approved changes to the labels and medication guides of fluoroquinolones taken by mouth or by injection. The boxed warning, the agency’s strongest drug warning, addresses these serious safety issues. The agency also updated the patient medication guide, the paper handout that comes with many prescription medicines.

According to Ge, people should check for the following:

  • Sudden pain, swelling, or stiffness, especially around the Achilles tendon (back of the ankle)
  • Tingling, burning sensations, or numbness in your hands or feet
  • Feeling confused, anxious, or having mood swings
  • Lightheadedness or irregular heartbeats 

“If anything feels off, don’t wait, contact your doctor right away,” she says.

If you have side effects while on any medication, you can file a report with the FDA’s MedWatch program.

Fluoroquinolones are a class of antibiotics used to effectively treat various bacterial infections, including complicated UTIs and pneumonia. While they gained popularity for being effective and easy to use, they can cause serious side effects, such as tendon damage and nerve issues, leading to concerns about their safety. The FDA advises not to use fluoroquinolones for common infections, such as acute sinusitis and bronchitis, recommending them only for more serious cases or when other antibiotics fail.

Are fluoroquinolones banned?

No. Fluoroquinolone antibiotics are still available in the U.S. They aren’t recommended for simple infections, but for more acute ones. They are also an important treatment option for people who are allergic to other antibiotics or can’t take them for other reasons.

Is Bactrim a fluoroquinolone?

No, Bactrim isn’t a fluoroquinolone. It is one brand name of a combination of two antibiotic types: sulfamethoxazole and trimethoprim.

Is amoxicillin a fluoroquinolone?

No, amoxicillin isn’t a fluoroquinolone. It is a penicillin.

Is hydroxychloroquine a fluoroquinolone?

No, hydroxychloroquine is not a fluoroquinolone. It is an antimalarial drug.

What are the psychiatric side effects of fluoroquinolone?

There are several psychiatric side effects related to fluoroquinolone. They include:

  • Anxiety
  • Depression
  • Hallucinations
  • Suicidal thoughts
  • Confusion