Go Ad-Free
logoThe People's Perspective on Medicine

Quinolone Antibiotics Can Cause Devastating Side Effects

Quinolone antibiotics can be very useful in treating dangerous infections but they can also cause severe reactions such as seizures.

Americans think of antibiotics as silver bullets. Our reverence for this type of medication is understandable. Before penicillin was developed, people routinely died from pneumonia and other infections. With this miracle of modern medicine, such deaths have become rare. However, the widespread use of quinolone antibiotics has gradually revealed some serious side effects.

Because antibiotics are perceived as wonder drugs, physician and patients tend to overlook their side effects. A little stomach upset or diarrhea seems like a small price to pay for curing a nasty infection.

The Downsides of Quinolone Antibiotics:

Sometimes, however, the side effects of certain antibiotics are unexpected and severe. One class in particular, fluoroquinolones, can cause unanticipated trouble. The most frequently prescribed are ciprofloxacin (Cipro), levofloxacin (Levaquin) and moxifloxacin (Avelox).


Readers of this column have shared some frightening experiences. One wrote:

“My husband took Levaquin for a sinus infection and within hours the tendons in his legs tightened and he could not walk. It took months for him to get better though he still has some residual leg pain.”


Another reported:

“Some ten years ago I was prescribed ofloxacin (Floxin) for a sinus infection. The next evening I woke up from sleep and began hallucinating that HUGE bats were flying around the room.

“The experience absolutely terrified me. I thought I was losing my mind. My sister, who was a pharmacy representative, had warned me not to take this antibiotic. I dismissed her warning as empirical hogwash. Needless to say, I had to learn the hard way.”


A parent described her daughter’s reaction:

“My 27-year-old daughter has spina bifida. I told the urologist treating her for an infection that she could not take Cipro because it had caused seizures. He said he wasn’t aware of that problem and that Levaquin was a chemical cousin and shouldn’t cause the same problem.

“On day four of the medication she had a seizure. That makes four times she’s had seizures on a quinolone, and it still took us the parents to make the connection. The doctors aren’t aware of this effect.”

Brain Fog:

A 19-year-old sent his report on a dreadful reaction to quinolone antibiotics:

“I am a college student who is still suffering the effects of Levaquin months later. My doctor prescribed it for painful urination with a fever. Within an hour of taking the first dose, my legs felt numb and it seemed like my brain was frying. I couldn’t explain to my mom what was happening and I could barely move. It wasn’t that I was paralyzed; more like I was walking on a water bed. I had no balance, my gait was terrible, and I couldn’t think.

“My doctor thought the neurological symptoms I was experiencing were due to fever and dehydration, but really it was a consequence of the Levaquin. I still have deep pains in my knees and feet and I am too weak to exercise as I used to. But the biggest problem that bothers me is the brain fog. I get lost easily, cannot remember things and had to withdraw from school. I am wired-tired and have great trouble sleeping.”

Suicidal Behavior:

According to the World Health Organization’s international database of adverse drug reactions, quinolones are linked to suicidal behavior (Psychopharmacology, July 2016). Researchers doing the analysis found 608 quinolone-associated suicidal events, including 97 completed suicides. This may seem extreme, but this lengthy story of one woman’s tribulations may help explain how someone could be driven to desperation.

Linda wrote a long description of a terrifying ordeal with quinolone antibiotics:

“On March 24, 1996, I went to a walk-in clinic for a suspected bladder infection. A culture was taken and I was given a prescription for Floxin, 300mg twice a day for six days. The culture came back negative. My blood pressure was 118/78. The nurse said that I had the blood pressure of a teenager.

“Sometime between the 24th and the 28th while at work, I had a bad headache and took two Advils. I found out later that you are not to take an NSAID with any quinolone. On March 28th, while at work I started having severe abdominal pain. I was seen by the county doctor that worked in my building. He asked me what I had eaten or if I had taken anything. I told him about the Floxin and he looked in his PDR. One of the side effects was abdominal pain; also at the very bottom it said can cause death. He had also taken my blood pressure and it read 140/90. (I was unaware of the reading.) He said,  “I wouldn’t give this medicine to anyone” and sent me home with Zantac.

“I worked for the County Elections Division, a very demanding job particularly during election time. We were doing all of the absent voter returns plus checking petitions and entering on to the system all new voter registration. We also had some new elections laws we were dealing with. And a new computer system we were using. I was in a lead position with a lot of responsibility. So I was no dummy. I loved the work and the deadlines that had to be met. When I returned to work the following day, the stomach pain was gone, but now my head felt fuzzy. I had started losing weight and having nightmares. The weight dropped so suddenly that my clothes were beginning to hang on me.

“I will never forget one nightmare. I was at work and had to go into another room and the door closed behind me. The room was dark but at the far end was a half opened door with a bright light shinning thru. I walked closer and there were three dead roses lying in front of the door. They were for my grandparents who had been dead for over sixty years. The third rose was the one that scared me. I was so frightened I ran back to the door I had come in and opened it, but it led to another dark room with no light and I couldn’t get out of it. I awoke to my husband shaking me and telling me I was moaning and thrashing around. I am telling you this only because it became such a threat to me.

“I continued to work with all the fuzziness in my head but other adverse symptoms began. My vision started blurring, I had excess salvia from the left side of my mouth, my left arm started to jerk and I started having signs of carpel tunnel. I began to have a rapid heart beat, and I was having a hard time functioning at work. I was in a complete fog. On the 11th of April I could stand no more. I left work. How I drove home I don’t know. I went straight to bed!

“The next day was even worse. I knew I needed to see a doctor. I was disoriented and my head felt like it was about to explode. My vision by now was terrible. I called my primary care physician (whom I had never seen, because I had always been healthy). His receptionist answered the phone. I told her I was ill and didn’t know what was the matter, but I needed help. She said the doctor had been on vacation and was booked solid for a month. I pleaded with her to make me an appointment because there was something terribly wrong with me. Her response was that she needed some kind of diagnoses, and that not feeling well wasn’t enough. I sure couldn’t give her a diagnosis; I could hardly talk. When she refused to make me an appointment, I went back to the walk-in clinic where I had been given the Floxin. They wouldn’t take me because I didn’t have a referral from my PCP. I was fighting for my life and every door was being shut in my face.

“After trying for days, I finally got the insurance company to give me permission to go to the clinic. I literally staggered into the office. They helped me back to a room and took my blood pressure it is 220/160 and the back of my head was killing me . They were able to bring my blood pressure down to an acceptable level 136/82 after eight hours. Now the kicker: while I was there they gave me 750 mg of ciprofloxin even though I was having a reaction to Floxin. I didn’t realize at the time that I was having a reaction, but surely the doctor should have known. He had my files in front of him that showed him he had given me Floxin. He sent home me after eight hours with a prescription for Cipro and my husband had it filled. I would have taken anything to get better, but everything just escalated from there. I wound up in the emergency room that night. I can hardly talk and I am numb and tingling on my left side, just like someone had split me right down the middle, everything on my left side felt weird.  The emergency doctor asked me if I had a rash; I didn’t then, but I had had one previously after taking the Floxin. I didn’t make the connection because I had forgotten the floxin. A CT scan came back normal. He suggested I see a neurologist.

“Well, that was a big mistake! I told him about the numbness and tingling in my head and face, my blurry vision, the pain I having in the back of my head, and how my skin was burning, especially the bottom of my feet. He had me touch my nose and walk toward him, heel to toe. I did. So he concluded I was just depressed although my blood pressure had gone back up to 140/90, my heart beat was rapid and of course the anxiety had set in by now and the insomnia was over whelming. I also tell him I feel removed (depersonalization) another side effect of the Cipro. He did do a urine test after I told him I had a hard time going. I showed I had some blood in my urine–another adverse reaction.

“My eyes were acting so weird. Before taking the quinolones I needed glasses only to read. The optometrist found palsy in my left eye plus my visual acuity is terrible. I just couldn’t get any doctor to help me. I was sitting at home and wham out of the blue I had an explosion in the back of my head where I had been complaining about the pain. It was just like a firework going off. It started small then burst out large. I called the Doctor and he told me to put ice on it. After a couple of hours the pain was worse than before. The doctor ordered an MRI of the brain–negative. I felt dizzy and had a fullness in my head, a feeling of pressure. I was beginning to see double. I would look at someone eyes and they would be stacked on top of each other. Letters would double up. Street lights had a halo around them and they were twice the size they should be. Walls would slant on me. While walking across the lawn, it would become wavy.

“By now I thought maybe I’m crazy. I saw a psychiatrist and told her all my symptoms. She seemed quite concerned about my symptoms and wrote to the doctor that although I seemed anxious, she thinks my complaints deserve further follow up. In the meantime I had surgery for carpel tunnel in both hands under workers comp. I was off work a long time. But I was able to maintain my insurance.

“One morning I was reading the paper and saw an article that Floxin causes tendon rupture of the Achilles. I showed the article to the doctor and he told me there is nothing wrong with my Achilles. I knew that. He tossed the article back at me and told me I had to get a grip.

“I didn’t feel safe even in bed. Fear had gripped hard. This whole episode was so hard on my husband. I didn’t know at the time how much this hurt him. He had always had a stable wife, one who took care of everything, he had always relied on me, and now the table had turned. I couldn’t function! I certainly wasn’t the person I was before the quinolones. He was so worried and there was nothing he could do but sit and watch me fall to pieces.  I had such a fear of dying I knew I had to leave the house. At the time my son and his wife and two babies were living with us, and I did not want them to see me die.

“I couldn’t take care of the house, I couldn’t cook. I couldn’t do anything. I tried sweeping the floor and my heart rate jumped to 110. I thought I was going to have a heart attack. I saw a different doctor finally. My new PCP reassured me he doesn’t think I am depressed, but he couldn’t find out what was wrong.I told him about the floxin and he says it should be out of my system by now. Maybe it is, but the damage has been done and it keeps doing damage.  I know I am dying. My body feels like it is being poisoned. I saw a rheumatologist, neurologist and ophthalmologist, but no one can figure out the problem. I lost weight from my previous 154 down to 120 lbs. I went from a size 12 to a 6. I had no stamina. I could hardly do my work.

“Three years later, saw the rheumatologist again. His exact words ‘Possible autoimmune disease. She does not fit a specific diagnosis. The features she demonstrates are intriguing however.’ I was healthy before I took the quinolones(Floxin/Cipro) Only a person who has suffered a reaction to the quinolones can appreciate the pain and the despair that has come from this drug. Doctors should know the consequences of these drugs. They are as ignorant of it as the patients they give it to. My nightmare: In my confused state and in my insomnia, I would try to go back to that dream and fight my way out of that darkened room, but I could never find a door. I hope someday there will be a door for all of us. And then it will be closed so no one else will ever have to go through this nightmare.”

Aortic Aneurysm and Dissection:

Another potential side effect of quinolone antibiotics is a ballooning of an aorta (aneurysm) or a fraying of its lining (dissection). A nationwide study in Sweden found that people taking a fluoroquinolone were significantly more likely to suffer from one of these potentially lethal reactions (BMJ, March 8, 2018). The absolute risk is not very high, just 1.2 cases per 1,000 person-years in people on the antibiotic compared to 0.7 cases per 1,000 person-years among those on a different antibiotic, amoxicillin. Nonetheless, the danger of such side effects should discourage anyone from taking these drugs unless there are no feasible alternatives.

An independent case-control study from Taiwan with more than 1,200 patients hospitalized for aortic aneurysm or aortic dissection found the risk was approximately double among people taking quinolone antibiotics (Journal of the American College of Cardiology, Sep. 18, 2018). Careful followup research found that ciprofloxacin can inflame the smooth muscle of the aorta and interfere with its integrity and ability to contract (JCI Insight, Jan. 24, 2023).

In Conclusion:

These quinolone antibiotics can help clear infections. They can also cause distressing side effects such as tendonitis, tendon rupture, insomnia, dizziness, confusion, hallucinations, psychosis, movement disorders, seizures and aortic aneurysms. Even silver bullets can cause serious damage.

Rate this article
4.4- 139 ratings
About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies..
Tired of the ads on our website?

Now you can browse our website completely ad-free for just $5 / month. Stay up to date on breaking health news and support our work without the distraction of advertisements.

Browse our website ad-free
  • Samyde J et al, "Quinolone antibiotics and suicidal behavior: analysis of the World Health Organization's adverse drug reactions database and discussion of potential mechanisms." Psychopharmacology, July 2016. DOI: 10.1007/s00213-016-4300-3
  • Pasternak B et al, "Fluoroquinolone use and risk of aortic aneurysm and dissection: nationwide cohort study." BMJ, March 8, 2018. DOI: 10.1136/bmj.k678
  • Lee C-C et al, "Oral fluoroquinolone and the risk of aortic dissection." Journal of the American College of Cardiology, Sep. 18, 2018. DOI: 10.1016/j.jacc.2018.06.067
  • Xiang B et al, "Ciprofloxacin exacerbates dysfunction of smooth muscle cells in a microphysiological model of thoracic aortic aneurysm." JCI Insight, Jan. 24, 2023. DOI: 10.1172/jci.insight.161729
Join over 150,000 Subscribers at The People's Pharmacy

We're empowering you to make wise decisions about your own health, by providing you with essential health information about both medical and alternative treatment options.