Ciprofloxacin: NHS information, uses and MHRA warnings

Ciprofloxacin is an antibiotic. It belongs to the fluoroquinolone class. It kills bacteria by blocking two enzymes. These are DNA gyrase and topoisomerase IV.

Bacteria need these enzymes to copy their DNA and divide. Ciprofloxacin is bactericidal, meaning it kills bacteria. This makes it effective against hard-to-reach or slow-to-clear infections.

Ciprofloxacin has a broad spectrum of activity. It works well against Gram-negative bacteria. Examples include *Escherichia coli*, *Klebsiella*, and *Pseudomonas aeruginosa*.

This makes it useful for urinary tract and prostate infections. Its effect on common Gram-positive bacteria, like many streptococci, is more limited.

So, it is not a first choice for most chest or skin infections.

In the UK, ciprofloxacin is a prescription-only medicine (POM). You cannot buy it over the counter. A doctor or qualified prescriber must decide if it is right for your infection. It comes as:

• tablets (250 mg, 500 mg and 750 mg)
• an oral suspension
• an intravenous infusion, used in hospital
• ear and eye drops for local infections.

Fluoroquinolones carry a risk of rare but serious side effects. UK prescribing guidelines have changed a lot recently. Ciprofloxacin is now a reserve antibiotic.

This means it is used when other options are not suitable, do not work, or are not tolerated. It is not a routine first choice.

Ciprofloxacin treats various bacterial infections. Its broad Gram-negative coverage is an advantage. It is used when other options are not appropriate. Common NHS uses include:

• complicated urinary tract infections (UTIs) and kidney infections (acute pyelonephritis)
• acute and chronic bacterial prostatitis, as it reaches prostate tissue well
• some gastrointestinal infections, like severe travellers' diarrhoea or typhoid fever, based on local resistance
• bone and joint infections, usually with specialist care
• certain respiratory infections, mainly for people with conditions like bronchiectasis or cystic fibrosis where *Pseudomonas* is present
• preventing serious infections after close contact with meningococcal disease, and treating or preventing anthrax exposure.

It is important to know what ciprofloxacin is not used for. It does not work against viruses, such as colds, flu, or COVID-19.

It is not a first-line treatment for simple, uncomplicated cystitis in women. For these, shorter courses of nitrofurantoin or trimethoprim are preferred in UK guidelines.

Your GP or hospital team will often send a urine or other sample for culture and sensitivity testing. This happens before or soon after you start treatment.

It confirms that the bacteria causing your infection are sensitive to ciprofloxacin. It also allows for a change to a narrower-spectrum antibiotic if needed.

Using reserve antibiotics carefully helps slow antibiotic resistance. This is a key priority for the NHS.

The dose of ciprofloxacin depends on the infection type and severity. Your kidney function and age also play a role. Typical adult oral doses in the BNF range from 250 mg to 750 mg twice a day.

• complicated lower UTI: 500 mg twice daily, usually for 7 days
• acute pyelonephritis: 500-750 mg twice daily for 7 days or longer
• acute prostatitis: 500 mg twice daily, often for 2-4 weeks
• chronic bacterial prostatitis: 500 mg twice daily for 4-6 weeks.

Your prescriber may use lower doses if you have reduced kidney function. This is because your kidneys largely clear ciprofloxacin from your body.

Here are practical tips for taking the tablets:

• Swallow them whole with plenty of water. You can take them with or without food.
• Do not take them with dairy products alone (milk, yoghurt). Also avoid calcium-fortified juice. Calcium binds the antibiotic and reduces absorption. A normal meal that includes some dairy is fine.
• Leave at least 2 hours before, or 4-6 hours after, any antacids, iron, zinc, calcium, or magnesium supplements.
• Drink fluids regularly during the course. This reduces the small risk of crystals forming in your urine.
• Space the two daily doses about 12 hours apart. Complete the course exactly as prescribed, even if you feel better sooner.

If you miss a dose, take it as soon as you remember. Do not take it if the next dose is nearly due. Never take a double dose.

If vomiting or severe diarrhoea stops you keeping the tablets down, contact your GP or NHS 111 for advice. The infection may not be treated properly.

The MHRA (Medicines and Healthcare products Regulatory Agency) has issued safety warnings. These are about fluoroquinolone antibiotics, including ciprofloxacin.

An EU-wide review by the European Medicines Agency led to restrictions. These were introduced in 2019 and strengthened in 2024.

In the UK, fluoroquinolones by mouth, injection, or inhalation should only be prescribed when other antibiotics are inappropriate.

This means, for example, when alternatives have failed, are not suitable, or are not tolerated.

The reason is a pattern of rare but serious side effects. These can sometimes be long-lasting or irreversible. They can affect more than one body system at once:

• Tendon damage and rupture, most often the Achilles tendon. This can happen within 48 hours of starting treatment. It can also occur months after stopping. The risk is higher for people over 60, those taking corticosteroids, and people with kidney problems or organ transplants.
• Peripheral neuropathy: tingling, burning, numbness, or weakness in the hands or feet.
• Central nervous system effects, including seizures, sleep problems, anxiety, depression, and confusion.
• Aortic aneurysm and dissection: a small increased risk of tears or bulges in the main artery. This is especially true for older people or those with existing aortic disease, high blood pressure, or connective tissue disorders like Marfan syndrome.
• Heart valve regurgitation (leaky heart valves) in susceptible patients.

Stop taking ciprofloxacin and contact a doctor straight away if you get tendon pain or swelling, pins and needles, muscle weakness, or mental health symptoms.

Seek emergency help for sudden severe chest, back, or abdominal pain. These warnings do not mean the medicine is unsafe for everyone. For the right infection, it can save lives.

But they explain why your GP will not prescribe it for minor, self-limiting infections.

Most people taking a short course of ciprofloxacin have few problems. The most common side effects affect up to 1 in 10 people. These are nausea and diarrhoea.

Other known effects include vomiting, abdominal pain, headache, dizziness, rash, and disturbed sleep. Ciprofloxacin can make your skin more sensitive to sunlight.

Use sunscreen and avoid sunbeds during treatment. Severe, persistent, or bloody diarrhoea can mean *Clostridioides difficile* infection. This needs prompt medical review.

Ciprofloxacin can prolong the QT interval on the heart's electrical recording.

Be careful if you have known QT prolongation, significant electrolyte problems, or take other QT-prolonging medicines. Examples include amiodarone or some antidepressants and antipsychotics.

Important interactions to know:

• Dairy products, antacids, and mineral supplements (calcium, magnesium, aluminium, iron, zinc) bind ciprofloxacin in the gut. This can greatly reduce absorption. Separate the doses as described above.
• NSAIDs like ibuprofen or naproxen taken with ciprofloxacin may increase seizure risk. This is especially true for people with epilepsy.
• Theophylline: ciprofloxacin raises theophylline levels. This can cause toxicity. This combination needs close monitoring or should be avoided.
• Tizanidine (a muscle relaxant) must not be taken with ciprofloxacin.
• Warfarin: the blood-thinning effect may be stronger. Extra INR checks are sensible.
• Caffeine is broken down more slowly. This can cause jitters or palpitations in sensitive people.

Always tell your prescriber and pharmacist about all medicines and supplements you take. This includes over-the-counter products.

Ciprofloxacin is a prescription-only medicine (POM) across the UK. GPs, hospital doctors, and some non-medical prescribers prescribe it.

Pharmacies dispense it against an NHS or private prescription. In England, the standard NHS prescription charge applies unless you are exempt.

Prescriptions are free in Scotland, Wales, and Northern Ireland. Websites offering ciprofloxacin without a prescription or prescriber assessment are illegal. You should avoid them.

The MHRA regularly takes action against such sellers.

Before prescribing, your clinician will consider:

• the type of infection and likely bacteria involved
• whether a narrower-spectrum or safer alternative would work
• your age, kidney function, and tendon or aortic risk factors
• other medicines that could interact
• any previous reaction to a fluoroquinolone. A previous serious side effect from any quinolone usually means avoiding the class for life.

During treatment, contact your GP or NHS 111 if your symptoms do not improve within 48-72 hours. Also contact them if you develop new symptoms, or experience any warning signs mentioned above.

You can report suspected side effects directly through the MHRA's Yellow Card scheme. This helps regulators monitor antibiotic safety.

Reliable sources for more information include the NHS website (patient-friendly guidance). The BNF published by NICE provides dosing and interactions for UK prescribers.

The electronic medicines compendium (EMC) hosts the official Patient Information Leaflet and Summary of Product Characteristics for every UK-licensed ciprofloxacin product.