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Ciprofloxacin: 7 things you should know

Medically reviewed by Carmen Fookes, BPharm. Last updated on Jan 9, 2020.

1. How it works

  • Ciprofloxacin is an antibiotic used to treat a wide range of infections. Ciprofloxacin converts two bacterial enzymes, topoisomerase IV and DNA gyrase, into toxic enzymes that inhibit the manufacture and repair of DNA and other DNA processes.
  • Ciprofloxacin belongs to a group of medicines known as fluoroquinolones (also called quinolones).

2. Upsides

  • Ciprofloxacin may be used to treat a wide range of infections such as those occurring in the urinary tract, prostate, respiratory tract, sinuses, bones and joints, abdomen, and genital area. However, it is usually only used in the treatment of urinary tract infections, chronic bronchitis, and sinusitis when other treatments have failed or cannot be used.
  • May also be used for the treatment of plague or uncomplicated gonorrhea, in addition to other infections.
  • May be given as a preventive measure when people have been exposed to anthrax.
  • Effective against susceptible strains of a number of different gram-positive and gram-negative bacteria, for example: Staphylococcus aureus (methicillin-susceptible strains only), S. epidermidis (methicillin-susceptible isolates), S. pyogenes, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Also effective against Enterobacter cloacae, Proteus mirabilis, Proteus vulgaris, Providencia stuartii, Morganella morganii, and Citrobacter freundii.
  • Available as oral tablets, extended-release tablets, oral solution, eye drops and in an injectable form.
  • Generic ciprofloxacin is available.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

  • Diarrhea, nausea, abnormal liver function tests, vomiting, and rash.
  • Tendonitis and tendon rupture, peripheral neuropathy (nerve pain in fingers and toes) and central nervous system effects (side effects that affect the brain including psychosis, convulsions, hallucinations) have been associated with ciprofloxacin and other fluoroquinolones. These side effects may be irreversible and they can all occur together in some patients. They may occur at any time after starting ciprofloxacin and in any patient. If any of these very severe side effects happen, ciprofloxacin should be discontinued immediately and all fluoroquinolones avoided in the future. The risk of tendonitis and tendon rupture is increased in people over the age of 60, in those taking corticosteroids, or with a history of organ transplant. Previous tendon disorders or strenuous activity may also increase risk.
  • May also cause anxiety, insomnia, psychotic reactions, nerve pain or a loss of feeling in the limbs, ECG abnormalities, increased sensitivity to light and other effects.
  • Should not be given to children under the age of 18 years unless they have certain serious infections that cannot be treated with other antibiotics. Children are more susceptible to the adverse effects of ciprofloxacin.
  • May exacerbate muscle weakness in people with myasthenia gravis.
  • Serious, sometimes life-threatening, adverse reactions such as liver damage and allergic reactions have been occasionally reported.
  • May trigger seizures or increase the risk of having a seizure.
  • May disturb blood glucose levels in people with diabetes; careful monitoring of blood glucose is required.
  • May cause photosensitivity reactions and severe sunburn on exposed areas of skin.
  • Not suitable for people with myasthenia gravis, certain heart rhythm disturbances, or pediatric patients (unless being given to prevent inhalation anthrax or plague). Dosage may need reducing in people with poor kidney function. May cause liver damage or heart rhythm disturbances.
  • May interact with some medications including antacids or preparations containing iron or zinc. Administer at least two hours before or two hours after these preparations.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

Ciprofloxacin is an effective antibiotic that treats a wide variety of infections; however, it should not be given to children aged less than 18 and in adults it should be reserved for infections that are not treated by other antibiotics. Side effects include tendinitis and tendon rupture.

5. Tips

  • Oral ciprofloxacin tablets may be taken with or without food. Take exactly as directed and for the time period indicated to reduce the risk of resistant bacteria developing, unless side effects force early discontinuation.
  • Only use when prescribed by a doctor to treat infections caused by susceptible bacteria as improper use increases the chance of resistant bacteria developing.
  • Do not take ciprofloxacin within two hours of magnesium/aluminum-containing antacids or other products containing calcium, iron or zinc. Other products may also affect absorption (check product information).
  • Avoid administration of ciprofloxacin with dairy products (eg, milk or yogurt) or calcium-fortified juices alone; however, ciprofloxacin may be taken with meals that contain calcium.
  • Protect yourself from sunlight and avoid excessive exposure to the sun when taking ciprofloxacin. Wear sunblock when outdoors.
  • Keep well hydrated when taking ciprofloxacin to avoid concentrations of ciprofloxacin becoming too high in the urine and precipitating out as crystals.
  • Discontinue ciprofloxacin immediately if you experience tendon pain, swelling, inflammation or rupture and contact your healthcare provider.
  • Seek medical advice if chronic diarrhea develops during or following ciprofloxacin.
  • Discontinue ciprofloxacin immediately and contact your healthcare provider if you experience pain, tingling, or numbness in your fingers and toes; or any central nervous system effects (such as paranoia, depression, hallucinations); a severe rash; jaundice (skin yellowing); a change in your heartbeat; or any sign of an allergic reaction.
  • Do not drive or operate machinery if ciprofloxacin makes you feel dizzy or tired. Avoid alcohol.

6. Response and Effectiveness

  • Peak concentrations of ciprofloxacin are reached one to two hours after dosing; however, it may take up to 48 hours before infection-related symptoms start to abate.

7. Interactions

Medicines that interact with ciprofloxacin may either decrease its effect, affect how long it works for, increase side effects, or have less of an effect when taken with ciprofloxacin. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with ciprofloxacin include:

  • antacids containing calcium, magnesium, or aluminum
  • anticonvulsants, such as phenytoin
  • blood-glucose-lowering agents, such as glimepiride or glyburide
  • caffeine
  • clozapine
  • corticosteroids, such as prednisone. May enhance the risk of tendonitis or tendon rupture
  • cyclosporine
  • bowel cleansing agents such as sodium picosulfate
  • diuretics
  • lactobacillus
  • methotrexate
  • NSAIDs such as ibuprofen, diclofenac, or naproxen
  • photosensitizing agents, such as aminolevulinic acid
  • probenecid
  • QTc-prolonging agents, such as amiodarone, domperidone, methadone, ondansetron, or haloperidol
  • sucralfate
  • supplements containing calcium, iron, or zinc
  • theophylline
  • tizanidine
  • warfarin
  • vaccinations, such as BCG, cholera, or typhoid
  • vitamin K
  • any medication that inhibits or induces CYP3A4 or CYP1A2.

Note that this list is not all-inclusive and includes only common medications that may interact with ciprofloxacin. Refer to the prescribing information for ciprofloxacin for a complete list of interactions.


Ciprofloxacin. Revised 06/2019.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use ciprofloxacin only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Copyright 1996-2021 Revision date: January 9, 2020.