Can you take Ciprofloxacin if allergic to penicillin? (ADR)

In this article, we’ll discuss whether you can take Ciprofloxacin if allergic to Penicillin or not. Furthermore, we will discuss the difference between Ciprofloxacin and Penicillin, symptoms of penicillin allergy, other alternative antibiotic options for people with penicillin allergies and the safety considerations associated with Ciprofloxacin use in penicillin allergy individuals. 

Can you take Ciprofloxacin if allergic to Penicillin?

Yes, you can take Ciprofloxacin if allergic to Penicillin but only if it is prescribed by your doctor. He/she will make sure that you’re not allergic to any other antibiotics then will prescribe you the relevant medication. 

Ciprofloxacin is not a Penicillin-based antibiotic and is usually considered safe in individuals sensitive to Penicillin. However, some individuals with Penicillin allergy might also develop Ciprofloxacin resistance as everyone reacts differently to medications. (1)

Ciprofloxacin belongs to the fluoroquinolone class of antibiotics. It is FDA-approved for the treatment of a broad range of bacterial infections which may include UTIs and respiratory tract infections among others. It exerts its action by inhibiting the activity of certain enzymes that are involved in the DNA replication of bacteria. (1)

Penicillin, on the other hand, is classified as a Beta-lactam antibiotic which works by inhibiting the synthesis of bacterial cell walls and ultimately killing or inactivating the bacteria and curing the infection. There are various types of penicillin-based antibiotics available including Penicillin G, Penicillin V, Amoxicillin and Ampicillin. (2)

Both Penicillin and fluoroquinolones (Ciprofloxacin) are found to target different bacterial components and cross-reactivity between them is considered uncommon. However, it’s best to consult your doctor before starting antibiotics especially when you have known allergies to ensure the safety of treatment. (1,2)

What does research suggest?

According to a research study, scientists investigated the effectiveness of Ciprofloxacin as an alternative for treating urinary tract infection (UTI) in patients with penicillin allergy. (3)

The researchers found out that patients with Penicillin allergy were more likely to have UTIs resistant to Ciprofloxacin. As per the report 24% of Penicillin-allergic patients who were receiving Ciprofloxacin as a substitute developed Ciprofloxacin-resistant UTI.

This study indicated that having a documented Penicillin allergy may result in less effective treatment with Ciprofloxacin particularly for UTIs. So, it’s important to keep in mind that antibiotic choices should be made carefully. The risk of antibiotic resistance and the specific characteristics of the infection being treated should also be kept in consideration. (3)

What are the key differences between Ciprofloxacin and Penicillin?

Here is how Ciprofloxacin and Penicillin differ from each other in various ways. (1,2)





Ciprofloxacin Fluoroquinolone antibiotic Target DNA gyrase and topoisomerase IV enzymes to stop their activity of bacterial DNA replication.

Broad spectrum antibiotic. 

Effective against Gram -ve and some Gram +ve bacteria. 

Penicillin Beta-lactam antibiotic Target bacterial cell walls and inhibit its synthesis, ultimately killing or inactivating the bacteria. 

Effective against Gram +ve bacteria.

Penicillin-G is particularly effective against gram +ve cocci.

What are the common symptoms of Penicillin allergy?

There are wide range of symptoms associated with Penicillin allergy which may vary in severity among individuals. Some common symptoms may include: (4)

Skin reactions

  • Hives (Urticaria) – Red/flash itchy bumps on the skin.
  • Rashes (Red or discoloured skin that may be itchy)

Respiratory symptoms

  • Runny or stuffy nose
  • Sneezing and watery eyes
  • Shortness of breath

Gastrointestinal symptoms:

  • Nausea and vomiting
  • Diarrhea

Anaphylaxis (severe and life-threatening allergic reaction)

  • Swelling
  • Difficulty breathing
  • Drop in blood pressure
  • Rapid heartbeat (tachycardia)

What other antibiotic alternatives are available for Penicillin allergy?

If an individual is allergic to Penicillin, there are a lot of antibiotic alternatives available from different classes that can be prescribed to treat the bacterial infection. (5)

However, this must be done under your doctor’s guidance as they will determine which alternative is best for your specific condition, such as the type of infection, the specific bacteria causing it and the individual’s medical history. Here I’m providing you with a list of some antibiotic options for people with Penicillin allergy. (5)


  • Erythromycin
  • Clarithromycin
  • Azithromycin

Cephalosporins: (with caution in severe allergies)

  • Cephalexin
  • Ceftriaxone
  • Cefuroxime


  • Levofloxacin
  • Moxifloxacin
  • Gemifloxacin


  • Doxycycline
  • Minocycline
  • Tetracycline


  • Vancomycin


  • Gentamycin
  • Tobramycin
  • Amikacin

How to ensure the safe use of Ciprofloxacin? 

Using Ciprofloxacin in patients with Penicillin allergy requires careful consideration and monitoring. Make sure if you are allergic to Penicillin inform your healthcare provider before starting Ciprofloxacin or any other antibiotic as this information is useful to make the appropriate decision regarding the choice of alternative. (1)

If your doctor has prescribed Ciprofloxacin as an alternative, make sure to follow the provided instructions regarding the dosage regime, frequency of dose and duration of course. Do not change the dose or stop taking it before the completion of the course as failure to do so will most likely result in antibiotic resistance. (1,5)

Inform your doctor about any pre-existing health condition or other known allergies, also provide them with the list of medications that you might have been taking in the past including all prescribed, OTC and herbal supplements.

Keep in mind that Ciprofloxacin absorption can be reduced by calcium, magnesium or aluminium-containing products, so better to avoid taking antacids and dairy products or keep a minimum 2-hour gap between the dose and these products to avoid interaction. (1)

Keep yourself well-hydrated during Ciprofloxacin use to prevent potential ADRs on kidneys and avoid drinking alcohol as it may interact with the antibiotic and exacerbate the risk of side effects. 

As a pharmacist, in my opinion, the majority of patients with Penicillin allergies don’t react negatively to Ciprofloxacin when following the right dose and monitoring the symptoms. In case, you experience any unusual symptoms inform your healthcare provider right away. 

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