What are the common side effects of Cipro (ciprofloxacin)?

Common Side Effects of Ciprofloxacin

Gastrointestinal disturbances are the most common side effects of ciprofloxacin, occurring in 2-8% of patients, with nausea being the most frequent complaint. 1, 2

Gastrointestinal Effects (Most Common)

• Nausea, vomiting, diarrhea, and abdominal discomfort affect 2-8% of patients and represent the most frequently reported adverse effects 2
• The FDA reports nausea specifically occurs in 0.5-1.8% of patients 3
• These symptoms are typically mild to moderate in severity and resolve without intervention 4

Central Nervous System Effects

• Dizziness and mild headache occur in 1-4% of patients 2
• CNS effects may occur after the first dose and include confusion, tremors, anxiety, nervousness, depression, and insomnia 1
• Seizures have been reported, particularly in patients with pre-existing CNS disorders or risk factors 1

Skin and Hypersensitivity Reactions

• Skin rashes or pruritus affect approximately 1% of patients 2
• Photosensitivity is a notable concern—ciprofloxacin makes skin sensitive to sunlight, potentially causing severe sunburn, blisters, or skin swelling 1
• Patients should use sunscreen, wear protective clothing, and avoid tanning beds during treatment 1

Musculoskeletal Effects (Critical Warning)

• Tendinitis and tendon rupture can occur, most frequently involving the Achilles tendon 1
• Risk is highest in patients over 60 years, those taking corticosteroids, and transplant recipients 1
• In pediatric patients (ages 1-17), musculoskeletal adverse events occurred in 9.3% compared to 6.0% in controls 3
• Patients must stop ciprofloxacin immediately at the first sign of tendon pain, swelling, or inflammation 1

Serious but Less Common Effects

Peripheral Neuropathy

• Nerve damage causing pain, burning, tingling, numbness, or weakness in extremities can occur 1
• May require immediate discontinuation to prevent permanent damage 1

Cardiac Effects

• QT interval prolongation leading to potentially fatal arrhythmias can occur 3
• Risk is elevated in elderly patients, those with family history of QT prolongation, low potassium levels, or concurrent use of antiarrhythmic medications 1

Hepatotoxicity

• Transient elevations in liver enzymes are usually trivial and reversible 2
• Yellowing of skin or eyes (jaundice) or dark urine requires immediate discontinuation 1

Clostridium difficile-Associated Diarrhea

• Pseudomembranous colitis can develop during treatment or up to 2+ months after completion 1
• Watery diarrhea, persistent diarrhea, bloody stools, stomach cramps, and fever warrant immediate medical attention 1

Overall Safety Profile

• Total incidence of adverse effects ranges from 3.0% (Europe) to 13.4% (USA, possibly due to higher dosages) 2
• Only 1.5% of patients discontinue treatment due to side effects, mostly gastrointestinal reactions 4
• 94% of adverse reactions are mild to moderate in severity 4
• Serious adverse effects occur in only 0.6% of patients 4

Important Drug Interactions

• Ciprofloxacin inhibits the CYP1A2 enzyme, causing dangerous elevations of theophylline, tizanidine, and clozapine levels 3
• Serious and fatal reactions including cardiac arrest, seizures, and respiratory failure have occurred with concurrent theophylline use 1
• Multivalent cations (magnesium, aluminum, iron, calcium) in antacids, supplements, and dairy products drastically reduce ciprofloxacin absorption 3
• Take ciprofloxacin at least 1-2 hours before or 4 hours after products containing these cations 3

Clinical Pitfall to Avoid

The most common reason for treatment discontinuation is gastrointestinal upset, but the most dangerous adverse effects are tendon rupture and peripheral neuropathy—both require immediate cessation of therapy. Do not dismiss musculoskeletal complaints as minor side effects. 1