10 Ciprofloxacin Interactions You Should Know About

Ciprofloxacin (Cipro) is an antibiotic used to treat bacterial infections in kids and adults, such as skin infections and bone and joint infections. It can also treat some sexually transmitted infections and lung infections, like pneumonia. It's a widely available and relatively affordable antibiotic.

Although ciprofloxacin is commonly used, it should be used carefully. It can cause some unique side effects. It can also interact with some medications and foods. If you or a loved one have been prescribed ciprofloxacin, it's important to know which medications, supplements, and foods may interact with it.

1. Medications known to affect your heart rhythm

Fluoroquinolone antibiotics, like ciprofloxacin, have a risk of affecting your heart rhythm. This can lead to abnormal heartbeats (arrhythmias). This risk is higher if you have a heart condition known as long QT syndrome, which can also lead to arrhythmias. 

If you combine ciprofloxacin with other medications that can affect your heart rhythm, the risk of this side effect is higher. Examples of medications that can affect your heart rhythm include:

• Amiodarone (Pacerone)

• Sotalol (Betapace)

• Ziprasidone (Geodon)

• Chlorpromazine 

• Tricyclic antidepressants (TCAs) like amitriptyline 

It’s best to avoid combining ciprofloxacin with other medications that can cause abnormal heartbeats. You should also avoid taking ciprofloxacin if you have heart-related health conditions, like long QT syndrome. If this is the case, there may be safer antibiotics that can be used to treat your infection.

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2. Diabetes medications

If you have diabetes, you may be taking an oral medication like metformin or a sulfonylurea like glipizide or glyburide (Diabeta, Glynase). These beneficial medications help lower and control your blood sugar levels.

However, ciprofloxacin can enhance the effects of some diabetes medications. While this may seem like a good thing, the combination could make your blood sugar drop too low. Symptoms of low blood sugar include feeling shaky, sweaty, and hungry. More severe symptoms are also possible. 

If you take an oral diabetes medication and are given a prescription for ciprofloxacin, try to check your blood sugar more often while you’re taking them together. Make sure to look out for signs and symptoms of low blood sugar, too. It’s also a good idea to have a fast-acting source of sugar on hand — such as glucose tablets or gel — to help reverse very low blood sugar levels, if needed. 

3. Warfarin

Warfarin (Coumadin, Jantoven) is a blood thinner used to prevent and treat blood clots. It can be easily affected by certain medications and foods.

Certain antibiotics, like ciprofloxacin, are known to interact with warfarin. It can enhance warfarin’s effects, causing your blood to become too thin. This may increase your risk of bleeding or bruising.

Tell your healthcare provider if you plan to start taking ciprofloxacin if you’re taking warfarin. They may recommend monitoring your blood work more often while taking this combination. If you’re already taking this combination, keep an eye out for any signs of new or unusual bruising or bleeding. This could include dark or bloody stools, bleeding gums, or nosebleeds

4. Theophylline

If you have asthma or chronic obstructive pulmonary disease (COPD), you may have heard of a medication called theophylline (Theo-24, Elixophyllin). Theophylline helps make it easier to breathe by relaxing the muscles of your airways. But ciprofloxacin and theophylline don’t get along. Ciprofloxacin can increase theophylline levels in the body. This interaction can be severe, so it's recommended to avoid taking them together.

If the combination can’t be avoided, your healthcare provider may want to check your theophylline levels more often or adjust your medication doses. You should also monitor for possible signs of high theophylline levels. Possible symptoms are headache, an increased heart rate, and seizures. 

5. Dairy products 

Dairy products are a part of everyday life for many people. But the calcium in dairy products can lower ciprofloxacin’s absorption in your body. This may make ciprofloxacin less effective, which could lead to an undertreated infection.

It's best to avoid taking ciprofloxacin with dairy products (like milk, cheese, and yogurt) or drinks fortified with calcium (like dairy-free milks or calcium-fortified juices). Try to separate these products from ciprofloxacin by at least 2 hours. 

However, it's OK to take ciprofloxacin with a meal that contains a small amount of dairy, like buttered noodles.

6. Medications or supplements containing magnesium, aluminum, calcium, iron, or zinc 

Certain medications or supplements that contain substances like calcium, magnesium, and aluminum can interact with ciprofloxacin. Iron and zinc can also interact. They can bind to ciprofloxacin and lower the amount of medication that’s absorbed by the body. When taken together, they can lower the availability of ciprofloxacin in the body by up to 85%. This means ciprofloxacin won’t be as effective at fighting infections. 

These substances are commonly found in some over-the-counter (OTC) multivitamins and supplements, so be sure to check the labels of these products before you take them with ciprofloxacin. Some are also available with a prescription. Examples of these products include:

• Antacids with aluminum salts (like Mylanta)

• Antacids with calcium salts (like Tums)

• Magnesium salts (like Milk of Magnesia)

• Iron supplements (like ferrous sulfate, ferrous gluconate, ferric citrate)

• Zinc supplements

• Sucralfate (Carafate)

• Sevelamer (Renvela)

Separating ciprofloxacin from these types of medications and supplements can help prevent this interaction. It's recommended to take ciprofloxacin at least 2 hours before or 6 hours after taking any products that contain these substances. This will allow your body to absorb ciprofloxacin better.

If timing medications is an issue, you can ask your pharmacist to help you create a medication schedule. You could also try a medication reminder app if you have a smartphone.

7. Zolpidem

Ciprofloxacin can interact with zolpidem (Ambien), a common sleep medication used to treat insomnia. The antibiotic can lead to higher levels of zolpidem in the body. This happens because ciprofloxacin interferes with zolpidem’s metabolism (breakdown), making it stay in your body longer. 

It's not recommended to take these medications together. If possible, it’s best to avoid the combination. If they are combined, you should look out for signs of too much zolpidem, like increased sleepiness, dizziness, and feeling lethargic. 

8. Duloxetine

Ciprofloxacin can interact with an antidepressant called duloxetine (Cymbalta). Ciprofloxacin may lead to higher levels of duloxetine in the body. In fact, ciprofloxacin has been shown to amplify duloxetine levels by 5 times the normal amount.

It's best to avoid taking ciprofloxacin with duloxetine. If they need to be taken together, you should look out for signs of higher duloxetine levels, such as sedation and slower reaction times. 

9. Tizanidine

A common muscle relaxer medication, tizanidine (Zanaflex), can also interact with ciprofloxacin. Ciprofloxacin can get in the way of tizanidine’s metabolism, which leads to higher levels of tizanidine in the body. This can enhance tizanidine’s effects and lead to increased side effects. 

It’s not recommended to take tizanidine with ciprofloxacin. Some studies have found the combination may result in dangerously high levels of tizanidine — in some cases up to 10 times higher. If taken together, look out for signs and symptoms of tizanidine toxicity, like low blood pressure, drowsiness, and dizziness.

10. Caffeine

Ciprofloxacin can cause caffeine to have a longer and more pronounced effect in your body. This means you're more likely to feel caffeine’s side effects, like jitteriness or a racing heart. 

If possible, it’s a good idea to reduce your caffeine intake while taking ciprofloxacin. This includes limiting caffeinated beverages like coffee, tea, and energy drinks. It can also include some OTC medications which contain caffeine, like Excedrin (acetaminophen/aspirin/caffeine).

When should I contact my healthcare provider about a ciprofloxacin interaction?

When possible, it’s best to prevent interactions from happening in the first place. If you’ve received a prescription for ciprofloxacin, make sure your healthcare provider or pharmacist has an updated medication list handy. This list should contain all medications and supplements you take. This will help them screen for interactions from the start.

If you experience any bothersome side effects after starting ciprofloxacin, reach out to your healthcare provider for guidance. Your symptoms may or may not be related to an interaction, so they can help offer tips on what to do next. But if your symptoms feel severe, seek medical attention right away.

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Written by:

Sonja Jacobsen, PharmD, BCPS, BCOP

Sonja Jacobsen, PharmD, BCPS, BCOP,  is a clinical oncology pharmacy specialist currently practicing in Seattle. She has been practicing as a pharmacist since 2015 and is licensed to practice in Washington state and North Carolina.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

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