Quinolone antibiotics (including ciprofloxacin) may cause serious and possibly permanent tendon damage (such as tendonitis, tendon rupture), nerve problems in the arms and legs (peripheral neuropathy), and nervous system problems. Get medical help right away if you have any of the following symptoms: pain/numbness/burning/tingling/weakness in your arms/hands/legs/feet, changes in how you sense touch/pain/temperature/vibration/body position, severe/lasting headache, vision changes, shaking (tremors), seizures, mental/mood changes (such as agitation, anxiety, confusion, hallucinations, depression, rare thoughts of suicide). Tendon damage may occur during or after treatment with this medication. Stop exercising, rest, and get medical help right away if you develop joint/muscle/tendon pain or swelling. Your risk for tendon problems is greater if you are over 60 years of age, if you are taking corticosteroids (such as prednisone), or if you have a kidney, heart, or lung transplant. This medication may make a certain muscle condition (myasthenia gravis) worse. Tell your doctor right away if you have new or worsening muscle weakness (such as drooping eyelids, unsteady walk) or trouble breathing. Discuss the risks and benefits with your doctor before using this medication.

Nausea, diarrhea, dizziness, lightheadedness, headache, or trouble sleeping may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly. Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Tell your doctor right away if you have any serious side effects, including: unusual bruising/bleeding, signs of a new infection (such as sore throat that doesn't go away, fever), signs of kidney problems (such as change in the amount of urine, red/pink urine), signs of liver problems (such as nausea/vomiting that doesn't stop, unusual tiredness, stomach/abdominal pain, yellowing eyes/skin, dark urine). Get medical help right away if you have any very serious side effects, including: severe dizziness, fainting, fast/irregular heartbeat, signs of a tear/break in the main blood vessel called the aorta (such as sudden/severe pain in the stomach/chest/back, shortness of breath). This medication may rarely cause a severe intestinal condition due to a bacteria called C. difficile. This condition may occur during treatment or weeks to months after treatment has stopped. Tell your doctor right away if you develop: diarrhea that doesn't stop, abdominal or stomach pain/cramping, blood/mucus in your stool. If you have these symptoms, do not use anti-diarrhea or opioid products because they may make symptoms worse. Use of this medication for prolonged or repeated periods may result in oral thrush or a new yeast infection. Contact your doctor if you notice white patches in your mouth, a change in vaginal discharge, or other new symptoms. A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any of the following symptoms of a serious allergic reaction: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Some products that may interact with this drug include: "blood thinners" (such as acenocoumarol, warfarin), strontium. Many drugs besides ciprofloxacin may affect the heart rhythm (QT prolongation), including amiodarone, dofetilide, quinidine, procainamide, sotalol, among others. This medication can slow down the removal of other medications from your body, which may affect how they work. Examples of affected drugs include duloxetine, fezolinetant, pirfenidone, tasimelteon, tizanidine, vorasidenib, among others. Avoid drinking large amounts of beverages containing caffeine (coffee, tea, colas), eating large amounts of chocolate, or taking over-the-counter products that contain caffeine. This drug may increase and/or prolong the effects of caffeine.