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What are quinolones?

Ciprofloxacin, levofloxacin, and ofloxacin are examples of quinolone antibiotics that treat serious, complicated infections

When an infection occurs, an antibiotic may be required to quickly and effectively treat the infection. But sometimes certain infections may be unusually complicated to treat. This is when the quinolone class of antibiotics may be the best choice. There are several different types of antibiotics that may be used for various infections, but quinolones (also known as fluoroquinolones) are a type of infectious disease medication used primarily when there is a concern for multidrug resistance from other antibiotics. In the chart below, there is information regarding common quinolones antibiotics, coupons for these medications, and their safety information for review.

List of quinolones

Drug name SingleCare savings Learn more
Baxdela (delafloxacin) Get Baxdela coupons Baxdela details
Cipro (ciprofloxacin) Get Cipro coupons Cipro details
Floxin (ofloxacin) Get ofloxacin coupons Ofloxacin details
Levaquin (levofloxacin) Get levofloxacin coupons Levofloxacin details
Tequin (gatifloxacin) Get gatifloxacin coupons Gatifloxacin details
Vigamox (moxifloxacin HCl) Get Vigamox coupons Vigamox details

Other quinolones

  • Avelox (moxifloxacin)
  • Cipro IV (ciprofloxacin)
  • Cipro XR (ciprofloxacin)
  • Penetrex (enoxacin)
  • Factive (gemifloxacin)
  • Maxaquin (lomefloxacin)
  • Proquin XR (ciprofloxacin)
  • Trovan (trovafloxacin)

What are quinolones?

Quinolones are a type of antibiotic used to help fight against various bacteria. Because of their inhibition of several different types of microorganisms, they are considered broad-spectrum antibiotics. They appear to be quite effective against gram-negative bacteria, especially Escherichia coli (E. coli) and Pseudomonas aeruginosa. 

There are quite a number of side effects associated with these antibiotics, so there has been guidance provided regarding its use by the U.S. Food and Drug Administration (FDA). Because of their potential adverse effects, they are not recommended for most common infections as less toxic antibiotics may be more suitable. Therefore, they are usually set aside for more serious, complicated infections that traditional antibiotics have not been successful against. They are also an excellent alternative when there may be an allergy to traditional antimicrobial agents such as penicillin or macrolide options—especially in pneumonia cases.

As with most antibiotics, the popularity of these medications has made quinolone resistance a huge concern and threatens its clinical effectiveness. E. coli is one of the most common pathogens seen with hospital-acquired bacterial resistance.

The theory behind quinolone or fluoroquinolone resistance is for a variety of reasons. One example is related to an alteration in the DNA gyrase found in bacteria that the quinolone antibiotic usually targets. This variation in the DNA makes the antibiotic less effective against bacteria that has the capability of making these adjustments.

Another theory is that some bacteria have been able to decrease their outer membrane permeability, causing the antibiotic not to be able to appropriately destroy or inhibit the cell wall of those bacteria as the antibiotic cannot penetrate the wall as effectively as before. Finally, some bacteria have had the ability to develop efflux pumps. These pumps have the capability of allowing bacteria to survive in the presence of antibiotics, which makes certain types of antibiotics ineffective.

Luckily, most E. coli antimicrobial resistance is harmless but close attention should always occur when prescribing quinolones. Alternative forms, like cephalosporins, may need to be considered that have less likelihood for this type of resistance. 

How do quinolones work?

Quinolone antibiotics are known to work against different bacteria by stopping their ability to grow and infect the cells in the body. This occurs by working against two different enzymes found in bacteria. The enzymes are topoisomerase IV and DNA gyrase. Both interfere with the synthesis of DNA replication. The quinolone antibiotics that work against topoisomerase IV are more effective against gram-positive microorganisms. Whereas, the quinolone antimicrobial agents that work against DNA gyrase are more effective against gram-negative bacteria. Fluoroquinolone antibiotics are a newer derivative of quinolones, and they are capable of antibacterial activity against both topoisomerase IV and DNA gyrase simultaneously. The newer fluoroquinolones also differ in the way they are absorbed, metabolized, and excreted in the body when compared to traditional quinolones.

What are quinolones used for?

There are a variety of illnesses that quinolones are effective against. They include:

Types of quinolones

First-generation quinolones

First-generation quinolone antibacterial agents are some of the first in their class but are rarely used today. These antibacterial agents are inhibitors against gram-negative bacteria except there is no susceptibility for Pseudomonas species. 

Uncomplicated urinary tract infections are most commonly treated with this type of antibiotic. They are unfortunately prone to antibiotic resistance of many bacteria and should be avoided in those individuals with poor renal function.

Examples of first-generation quinolone antibiotics: Negram, Cinobac

Second-generation quinolones

Second-generation quinolone antibiotics are also effective against gram-negative bacteria like first-generation antibiotics. They also have susceptibility against Pseudomonas species. In addition, they possess some gram-positive bacteria coverage like Staphylococcus aureus—but not Streptococcus pneumoniae. 

These antibiotics are also useful with treatment against uncomplicated and complicated urinary tract infections, pyelonephritis, sexually transmitted diseases, prostatitis, bone infections, and skin/soft tissue infections.

Examples of second-generation quinolone antibiotics: Cipro, Floxin, Maxaquin

Third-generation quinolones

Third-generation antibiotics have an even more extensive spectrum of activity against bacteria than the first two generations. They include the same coverage as generation two quinolones but also have more susceptibility against gram-positive organisms such as penicillin-sensitive S. pneumoniae or penicillin-resistant S. pneumoniae. There is also expanded activity against atypical pathogens (Mycoplasma pneumoniae and Chlamydia pneumoniae)

The newer versions also allow for daily or twice daily dosing, decreasing the frequency of taking the medication. These more modern forms of quinolones also have the pharmacokinetics to treat lower respiratory tract infections that were not available with previous options. Various types of infections can be treated including all of the previous conditions mentioned previously along with chronic bronchitis and community-acquired pneumonia.

Examples of third-generation quinolone antibiotics: Avelox, Levaquin, Tequin

Fourth-generation quinolones

Fourth-generation quinolones have the most coverage against various bacteria of all the quinolone generations as it has the best tissue penetrations. Streptococcus pneumoniae and Pseudomonas are included in this class, but they also have the capability to fight against anaerobic bacteria. 

Unfortunately, they also have the most serious potential complications and side effects with their use. Due to this, they are usually limited for use of life- and limb-threatening infections. It is also restricted or recommended that it should be taken for no longer than 14 days. 

It has extensive coverage against many medical conditions including all of the first three generations’ illnesses but also intra-abdominal infections, nosocomial pneumonia, and pelvic infections. They do not effectively treat complicated urinary tract infections or pyelonephritis.

Examples of fourth-generation quinolone antibiotics: Trovan

Who can take quinolones?

Overall, quinolones are considered safe options to treat a variety of different types of pathogens for both men and women. 

Pregnancy and breastfeeding

Quinolone antibiotics should never be the first line of treatment as there are other less toxic options especially in those who are pregnant or breastfeeding. Quinolones can be used if needed during pregnancy, but the risks versus benefits should strongly be accessed by your healthcare provider. There is some data that shows concern for spontaneous abortion or damage to bone or cartilage to the unborn child with use in quinolone antibiotics. Also, quinolones are not recommended while breastfeeding as there is a concern for infant gastrointestinal complications.


Quinolones are not recommended in children up to 18 unless it is serious resistant strains of pathogens that first-line antibiotics have not been successful with treating. Children are believed to be more susceptible to developing adverse effects associated with quinolone antibiotics. They usually include gastrointestinal complications but there is also a more serious concern for damage to weight-bearing joints. 

Other restrictions

Seniors, patients on long-term steroid therapy, or organ transplant patients may want to avoid quinolones as they are at higher risk for developing tendon ruptures, peripheral neuropathy, or central nervous system implications. 

When prescribing these medications, a licensed healthcare professional will need to be aware of the several known complications and various drug interactions associated with these antimicrobial agents to prescribe safely.

Are quinolones safe?


Quinolone antibiotic restrictions

Do not use quinolones if you have:

  • Hypersensitivity to medication
  • History of cardiac disease particularly problems with the QT interval
  • History of high blood pressure
  • Marfan syndrome
  • Myasthenia gravis
  • Ehlers-Danlos syndrome
  • 60 years of age or older
  • Risk of or prior history of aortic aneurysm
  • Irregularities with electrolytes

Are quinolone antibiotics controlled substances?

Quinolones antibiotics are not a controlled substance as there is no risk of dependency from the use of these medications. 

Common quinolones side effects

There are a variety of common side effects seen with quinolone use. Some complications to be on the lookout for include:

  • Nausea
  • Diarrhea
  • Vomiting
  • Abdominal pain
  • Headache
  • Indigestion
  • Dizziness
  • Restlessness
  • Lightheadedness
  • Vaginitis
  • Insomnia
  • Reaction to the sun
  • Itching
  • Rash
  • Anxiety
  • Agitation
  • Confusion
  • Tendinitis
  • Joint pain
  • Elevated liver enzymes
  • Muscle pain
  • Disorientation
  • Problems with focusing
  • Nervousness
  • Impaired memory
  • Delirium
  • Paranoia
  • Hallucinations
  • Nightmares
  • Tremor
  • Low blood sugars

More severe adverse effects include:

  • Hypersensitivity reaction
  • Acute severe allergic reaction
  • Severe skin reaction
  • Vasculitis
  • Inflammation of lungs
  • Serum sickness
  • Phototoxicity
  • C. difficile associated diarrhea
  • Superinfection
  • Seizures
  • Increased intracranial pressures
  • Toxic psychosis
  • Depression
  • Suicidality
  • QT prolongation in the heart
  • Torsades de pointes
  • Renal toxicity
  • Crystals in urine
  • Liver toxicity
  • Decreased bone marrow
  • Blood disease
  • Peripheral neuropathy
  • Tendon rupture
  • Myasthenia gravis exacerbation
  • Aortic aneurysm
  • Aortic dissection

RELATED: Ciprofloxacin side effects and how to avoid them

How much do quinolones cost?

Although the antibacterial quinolones are not a first-line antibiotic therapy for many bacteria, these antibiotics are quite commonly prescribed by healthcare providers. They tend to be more expensive than first-line antibiotics especially when treating simple infections. If you are required to take a quinolone antibiotic, it may cost $100 to $2,000 for a prescription. If you need to use these types of antibiotics, consider using free SingleCare coupons to help reduce costs.