Is it safe to take Metronidazole (Nidazole) and Ciprofloxacin with Tadalafil (Cialis)?

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Last updated: July 6, 2025View editorial policy

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From the Research

It is not safe to take metronidazole (Nidazole) and ciprofloxacin together with tadalafil (Cialis) without medical supervision due to potential drug interactions. The combination of ciprofloxacin with tadalafil is particularly concerning as ciprofloxacin can inhibit the enzyme that metabolizes tadalafil, potentially leading to increased tadalafil levels in your bloodstream, as shown in a study published in 2006 1. This could cause dangerous side effects such as severe hypotension (low blood pressure), dizziness, fainting, and priapism (prolonged erection). Metronidazole may also interact with tadalafil, though the interaction is generally less severe than with ciprofloxacin. Additionally, both antibiotics can cause side effects like nausea, headache, and dizziness, which might be worsened when combined with tadalafil.

Some key points to consider:

  • Ciprofloxacin can increase the bioavailability of tadalafil, leading to increased risk of side effects, as demonstrated in a study published in 2006 1.
  • Metronidazole may also interact with tadalafil, although the interaction is generally less severe than with ciprofloxacin.
  • Both antibiotics can cause side effects that might be worsened when combined with tadalafil.
  • A study published in 2015 2 showed that ciprofloxacin can attenuate the antibacterial activity of phosphodiesterase inhibitors, which could lead to reduced efficacy of the antibiotic.

If you need to take these medications, you should consult with your healthcare provider first. They may recommend adjusting the dosage of tadalafil, spacing the medications apart, or temporarily discontinuing tadalafil while you complete your antibiotic treatment. Never adjust medication schedules on your own without professional medical advice. It's also worth noting that tadalafil has been shown to be well-tolerated in clinical trials, with a low incidence of serious cardiovascular adverse events, as reported in a study published in 2006 3. However, the potential interactions with ciprofloxacin and metronidazole must be carefully considered to minimize the risk of adverse effects.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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