Ciprofloxacin
Pronunciation: sip-roe-FLOKS-a-sin.
- Generic name
- ciprofloxacin
- Brand names
- Cipro (United States)
- Drug class
- Fluoroquinolone antibacterial
- Form
- Tablet / oral suspension / intravenous infusion
- Route
- Oral (tablet, oral suspension) or intravenous, depending on formulation and indication
- Legal status
- Prescription-only medicine in all 6 standard markets reviewed.
Availability and supply rules vary by country
Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand
Australia: APO-Ciprofloxacin (5) · Full directory
Boxed warning: Serious, sometimes irreversible reactions affecting tendons, nerves, and the nervous system; risk of worsening myasthenia gravis
Fluoroquinolone antibacterials, including ciprofloxacin, have been associated with disabling and potentially irreversible serious adverse reactions that can occur together, including tendinitis and tendon rupture, peripheral neuropathy, and central nervous system effects (such as seizures, increased pressure inside the skull, and psychiatric reactions). A prescriber will decide right away whether ciprofloxacin needs to be stopped at the first sign of any of these reactions. Ciprofloxacin can also worsen muscle weakness in people with myasthenia gravis and is contraindicated in this condition. (1) (2) (4)
What ciprofloxacin is and how it works
Ciprofloxacin is a fluoroquinolone antibacterial medicine used to treat a range of bacterial infections, including urinary tract, respiratory, skin, bone/joint, and gastrointestinal infections, when other, commonly recommended antibiotics are considered inappropriate. (1) (2)
Ciprofloxacin carries important safety warnings that set it apart from many other antibiotics: it can cause disabling and sometimes irreversible effects on tendons, nerves, and the nervous system, and it can worsen myasthenia gravis. It can also affect heart rhythm and interacts with several common medicines and supplements, so it is important to share your full medicine list with your prescriber and pharmacist.
Mechanism of action: how ciprofloxacin works
Ciprofloxacin is a fluoroquinolone that inhibits bacterial DNA gyrase and topoisomerase IV, enzymes required for bacterial DNA replication, transcription, and repair. (1) (2)
What ciprofloxacin is used for
Bacterial infections in several body systems
Used for urinary tract infections, lower respiratory tract infections, skin and soft-tissue infections, bone and joint infections, intra-abdominal infections, infectious diarrhoea and typhoid fever, chronic bacterial prostatitis, and gonorrhoea, reserved for situations where other, commonly recommended antibacterial agents are considered inappropriate for the infection. (1) (2) (6)
Anthrax post-exposure and plague
Used to reduce the risk of disease progression after suspected exposure to inhaled anthrax, and for plague, under specialist direction. (1) (6)
Before taking ciprofloxacin
Do not take / not appropriate for
- Do not take ciprofloxacin if you have myasthenia gravis; it is contraindicated in this condition because it can worsen muscle weakness, including breathing difficulty. (all patients) (1) (2)
- Do not take ciprofloxacin together with tizanidine; this combination is contraindicated because ciprofloxacin markedly raises tizanidine levels in the blood. (all patients) (1) (2)
- Do not take ciprofloxacin if you have had a hypersensitivity reaction to ciprofloxacin or any other quinolone antibiotic. (all patients) (1) (2)
Tell your clinician about
- Any personal history of tendon problems, myasthenia gravis, seizures, or mental health conditions.
- Whether you or a family member has a history of an irregular heart rhythm, QT prolongation, or low blood potassium.
- Whether you have a personal or family history of aortic aneurysm or connective tissue disorders such as Marfan or Ehlers-Danlos syndrome.
- Whether you are pregnant, plan to become pregnant, or are breastfeeding.
- Every other medicine and supplement you take, especially tizanidine, theophylline, warfarin or other blood thinners, antacids, calcium/iron/zinc supplements, corticosteroids, and antidiabetic medicines.
- Whether you have kidney problems or have had an organ transplant.
How to take ciprofloxacin
- Take exactly as prescribed by your prescriber; dosing, strength, and duration are individualised based on the infection being treated, your kidney function, and other factors.
- Swallow tablets with water; oral suspension should be measured and shaken as directed by your pharmacist.
- Take ciprofloxacin at least 2 hours before or 6 hours after antacids, calcium-fortified products (including dairy), and iron or zinc supplements, since these can reduce its absorption.
- Complete the full course as prescribed unless your prescriber directs otherwise.
- Drink plenty of fluids while taking ciprofloxacin, and avoid excessive sun or UV light exposure because of a photosensitivity risk.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6)
Missed dose
Take the missed dose as soon as you remember, unless it is almost time for your next dose, in which case skip the missed dose and continue with your regular schedule. Do not double the next dose to make up for a missed one. Ask your pharmacist or prescriber if you are unsure.
Overdose
Contact your prescriber, pharmacist, or a poison-control/emergency service if an overdose is suspected. Seek emergency medical help for any severe symptoms. (1)
Side effects
Nausea and diarrhoea are commonly reported. Some effects, on tendons, nerves, the heart rhythm, mood, or the liver, need prompt medical evaluation rather than waiting to see if they improve.
Nausea and diarrhoea
What to notice: Commonly reported digestive effects.
What to do: Tell your prescriber if severe or persistent. (1)
Abnormal liver function test results
What to notice: Usually detected on blood tests rather than felt directly.
What to do: Attend any blood tests your prescriber orders. (1)
Rash
What to notice: Skin rash has been commonly reported.
What to do: Tell your prescriber, especially if the rash is widespread or blistering. (1)
Tendon pain or swelling
What to notice: Pain, swelling, or inflammation in a tendon, particularly the Achilles tendon.
What to do: Contact your prescriber promptly and rest the affected area; a clinician will decide whether ciprofloxacin needs to be stopped. (1) (2)
Nerve symptoms (peripheral neuropathy)
What to notice: New pain, burning, tingling, numbness, or weakness in the arms or legs.
What to do: Contact your prescriber promptly; this effect can be irreversible and a clinician will decide on next steps. (1)
Severe diarrhoea (possible antibiotic-associated colitis)
What to notice: Severe, watery, or bloody diarrhoea, with or without fever and abdominal cramping, that can start during treatment or up to several months after.
What to do: Contact your prescriber promptly for assessment. (1) (2)
Possible liver problem
What to notice: Unusual tiredness, loss of appetite, yellowing of the skin or eyes, or dark urine.
What to do: Contact your prescriber promptly for liver-function testing. (1) (2)
Serious warnings
Tendinitis and tendon rupture — boxed_warning
Symptoms: Pain, swelling, or inflammation in a tendon, most often the Achilles tendon; a snapping or popping sound with sudden pain can indicate rupture.
Action: Contact your prescriber promptly and rest the affected limb; a clinician will decide whether ciprofloxacin needs to be stopped. Risk is higher in people over 60, those taking corticosteroids, and organ transplant recipients. (1) (2) (4)
Peripheral neuropathy — boxed_warning
Symptoms: Pain, burning, tingling, numbness, or weakness in the arms, hands, legs, or feet.
Action: Contact your prescriber promptly; this effect can be irreversible and a clinician will decide whether ciprofloxacin needs to be stopped. (1)
Central nervous system effects, including seizures and psychiatric reactions — boxed_warning
Symptoms: Seizures, severe headache with confusion (possible increased pressure inside the skull), tremor, restlessness, confusion, hallucinations, depression, or suicidal thoughts.
Action: Seek emergency medical help for a seizure, hallucinations, or any thoughts of self-harm; a clinician will decide whether ciprofloxacin needs to be stopped. (1) (2)
Worsening of myasthenia gravis — boxed_warning
Symptoms: New or worsening muscle weakness, including difficulty breathing or swallowing.
Action: Ciprofloxacin is contraindicated in myasthenia gravis; seek emergency medical help for any new breathing or swallowing difficulty. (1) (2)
Heart rhythm changes (QT-interval prolongation) — emergency
Symptoms: Fast or irregular heartbeat, dizziness, or fainting.
Action: Seek emergency medical help for fainting or a fast, irregular heartbeat; risk is higher with certain other heart-rhythm medicines or low blood potassium. (1) (2)
Aortic aneurysm and dissection — emergency
Symptoms: Sudden, severe pain in the chest, back, or abdomen.
Action: Seek emergency medical help immediately; risk is increased in elderly patients and those with a personal or family history of aneurysm or connective tissue disorders. (1) (2)
Severe allergic reaction (anaphylaxis) and severe skin reactions — emergency
Symptoms: Facial or throat swelling, difficulty breathing, widespread rash, or blistering/peeling skin.
Action: Seek emergency medical help immediately for any of these symptoms. (1)
Antibiotic-associated colitis (Clostridioides difficile) — high caution
Symptoms: Severe, watery, or bloody diarrhoea, with or without fever and abdominal cramping, that can occur during treatment or up to several months after stopping.
Action: Contact your prescriber promptly for assessment. (1) (2)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Tizanidine | Ciprofloxacin markedly increases tizanidine blood levels, increasing the risk of low blood pressure and excessive drowsiness. | This combination is contraindicated; tell your prescriber if you take tizanidine so an alternative can be arranged. (1) (2) |
| Antacids, calcium/iron/zinc supplements, and dairy or calcium-fortified products | Reduce absorption of ciprofloxacin, potentially making it less effective. | Separate dosing by at least 2 hours before or 6 hours after these products. (1) (2) |
| Theophylline | Ciprofloxacin can raise theophylline blood levels, and serious, sometimes fatal reactions have been reported. | Tell your prescriber if you take theophylline so levels can be monitored closely. (1) (2) |
| Warfarin and other blood thinners | Ciprofloxacin can enhance the anticoagulant effect, increasing bleeding risk. | Your prescriber may monitor your blood clotting (INR) more closely. (1) (2) |
| Oral antidiabetic medicines | Can increase the risk of severe low blood sugar (hypoglycaemia). | Tell your prescriber if you take diabetes medicines so your blood sugar can be monitored. (1) |
| Methotrexate | Ciprofloxacin can reduce methotrexate's renal clearance, increasing the risk of methotrexate toxicity. | This combination is generally not recommended; tell your prescriber if you take methotrexate. (2) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy
Extensive clinical experience has not shown an increased risk of major birth defects, but ciprofloxacin should be used in pregnancy only when your prescriber judges the potential benefit justifies the potential risk. (1) (2)
Breastfeeding
Breastfeeding is generally not recommended during treatment because of potential effects on the infant; discuss feeding options with your prescriber. (1) (2)
Older adults
People over 60 have a higher risk of tendon problems and aortic aneurysm/dissection; tell your prescriber about any tendon history or family history of aneurysm. (1) (4)
Children and adolescents
Use in children is generally limited to specific situations such as complicated urinary tract infections, cystic fibrosis pulmonary exacerbations, or post-exposure anthrax, under specialist direction. (6) (2)
Monitoring
Before starting
- Review of personal and family history of tendon problems, myasthenia gravis, seizures, heart rhythm problems, and aortic aneurysm.
- Full medicine and supplement list reviewed for interactions, especially tizanidine, theophylline, and warfarin.
During treatment
- Watch for tendon pain or swelling, nerve symptoms, mood or CNS changes, and signs of severe diarrhoea.
- Periodic liver function monitoring may be arranged for longer courses or if symptoms suggest a problem.
- Report any fainting, palpitations, or sudden severe chest/back/abdominal pain immediately.
Storage
Store tablets at controlled room temperature. Reconstituted oral suspension should be stored below 30C (86F) for up to 14 days and protected from freezing.
Study the drug class: Fluoroquinolones
Professional information
Clinician-facing context only. Use the current local product information in full.
United States
Indication: Varies by infection type and severity
Dose summary: Individualised by indication, severity, and renal function; typical adult oral regimens range from 250 mg to 750 mg every 12 hours; IV regimens are separately specified. Use current DailyMed label for indication-specific tables.
Renal context: Dose adjustment required for reduced creatinine clearance; see current product information for the specific adjustment table. (1)
Hepatic guidance
Hepatic necrosis and hepatic failure have been reported rarely; a clinician will assess and decide on treatment continuation if liver-related symptoms or abnormal liver tests occur.
Overdose note
Manage per local poison-control and toxicology guidance; no specific antidote is described in the reviewed labels. (1) (2)
Frequently asked questions
Why does ciprofloxacin have a boxed warning?
Ciprofloxacin, like other fluoroquinolone antibiotics, has been linked to disabling and sometimes irreversible effects on tendons, nerves, and the nervous system, and it can worsen myasthenia gravis. These reactions are uncommon but serious, which is why the warning is prominent and why prompt reporting of tendon pain, nerve symptoms, or mood/CNS changes matters. (1)
Can I take ciprofloxacin with milk or antacids?
Dairy products, calcium-fortified foods, antacids, and iron or zinc supplements can reduce how much ciprofloxacin your body absorbs. Take ciprofloxacin at least 2 hours before or 6 hours after these products. (1) (2)
Why is ciprofloxacin not used for every infection?
Because of its serious potential side effects, ciprofloxacin is generally reserved for infections where other, commonly recommended antibiotics are considered inappropriate. (2) (6)
What is the mechanism of action of ciprofloxacin?
Ciprofloxacin is a fluoroquinolone that inhibits bacterial DNA gyrase and topoisomerase IV, enzymes required for bacterial DNA replication, transcription, and repair. (1) (2)
References
- CIPRO (ciprofloxacin hydrochloride) tablet, film coated -- full prescribing informationU.S. Food and Drug Administration / DailyMed (NIH), full prescribing information · United States · accessed 2026-07-30 · source 1
- Ciprofloxacin 500 mg film-coated tablets -- Summary of Product Characteristicselectronic medicines compendium (emc), United Kingdom · United Kingdom · accessed 2026-07-30 · source 2
- Quinolone- and fluoroquinolone-containing medicinal products -- referral (covers ciprofloxacin)European Medicines Agency (EMA), Article 31 referral outcome · European Union · accessed 2026-07-30 · source 3
- pms-CIPROFLOXACIN (Ciprofloxacin Tablets USP) Product Monograph, Pharmascience Inc.Health Canada product monograph · Canada · accessed 2026-07-30 · source 4
- APO-CIPROFLOXACIN ciprofloxacin 500 mg (as hydrochloride) tablet -- ARTG entryTherapeutic Goods Administration (TGA), Australia · Australia · accessed 2026-07-30 · source 5
- Ipca-Ciprofloxacin 250 mg, 500 mg, 750 mg film-coated tablets -- New Zealand Data SheetMedsafe (New Zealand regulator) · New Zealand · accessed 2026-07-30 · source 6
Brand names by country
Single-ingredient ciprofloxacin names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- Ciprofloxacin in Dextrose400 mg/200mL, 200 mg00mL · hospira, inc.
- Cipro250 mg, 500 mg · bayer healthcare pharmaceuticals inc.
- CILOXAN3 mg/g · sandoz inc
United Kingdom
- Ciprofloxacin (generic) (2)MHRA licensed emc smpc confirmed · 250 mg, 500 mg, 750 mg · multiple UK generic manufacturers
Canada
- CIPRO
- CIPROFLOXACIN INTRAVENOUS INFUSION
- CILOXAN
- CIPRO XL
- APO-CIPROFLOX
- RAN-CIPROFLOX
- MINT-CIPROFLOX
- PMS-CIPROFLOXACIN XL
Australia
- APO-Ciprofloxacin (5)TGA ARTG registered 2007-08-07 confirmed · 500 mg, 750 mg · Apotex Pty Ltd
New Zealand
- Ipca-Ciprofloxacin (6)Medsafe approved confirmed · 250 mg, 500 mg, 750 mg · Ipca Laboratories (NZ distributor)
View brands in additional countries.
European Union
Ciprofloxacin (generic, nationally authorised in each member state) (3)