Antibiotics Linked To Increased Risk Of Colon Cancer And Sudden Cardiac Death


The overuse of antibiotics has been a concern for many years now. 

While we once thought these medications to be miracle drugs in the arena of infection fighting, this status quickly turned disastrous when these drugs began to be overprescribed and overused. 

When used too frequently, antibiotics can have a negative effect on the gut microbiome, and eventually the bacteria housed there can change so much that antibiotics are powerless to fight against them. 

And, while that issue is troubling enough, there are even greater concerns, potentially deadly concerns, when it comes to antibiotic usage. 

A few (specific) antibiotics have been linked to sudden cardiac death, and the general overuse of antibiotics is linked to a rise in colon cancer in young people.  

Between antibiotic resistance, sudden death, and a rise in colon cancer amongst younger populations, it’s important to know what these drugs can do to your health and which drugs are causing these ills so you can avoid these risks should you be prescribed an antibiotic. 

The Pitfalls Of Antibiotic Usage

The CDC calls antibiotic resistance “one of the world’s most pressing public health concerns.” 

And, while this seemingly drastic statement is said to be a concern primarily in low-income and developing countries, we simply can’t ignore the fact that the overuse of antibiotics is a problem here in the US as well. 

Antibiotics were generally regarded as having no apparent adverse effects, but a usage increase of 65% from 2000-2015 proved to many the great detriment these drugs can cause to the health of the gut microbiome. 

Millions upon millions of bacteria dwell within your gut, and this microbiome exists in a delicate balance of both good and bad bacteria. 

The health of your entire body depends on the balance of this bacterial community, and this is where antibiotics can wreak havoc. 

When you take an antibiotic for a bacterial infection. The goal is for the antibiotic to kill off the bad bacteria that is making you sick. 

The problem here is that antibiotics don’t differentiate between good and bad bacteria, they “kill” all bacteria. 

And, since balance within the gut requires a ratio of roughly 85% good bacteria to 15% bad bacteria, when antibiotics throw this balance off, a wide range of consequences can occur. 

  • Exposure to antibiotics early in life can cause childhood asthma, allergies, and airway illnesses.
  • Observational studies have found antibiotic usage (not necessarily overuse) to be linked to weight gain and obesity, gastrointestinal infections, inflammatory bowel disease, and colorectal cancer. 
  • And, as we mentioned earlier, the overuse of antibiotics can cause bacterial antibiotic resistance, causing bacteria to no longer respond to antibiotic usage. 

But, what’s even more troubling is the rising number of instances of sudden cardiac death which have been linked to specific antibiotics. 

Antibiotics Linked To Sudden Cardiac Death

A few popular antibiotics have been linked to sudden, fatal, cardiovascular events.

For one antibiotic, this danger was amplified when taken with other common medications. 

And, though some experts believe the risk to be small, we’re simply listing the facts here to make you aware of the potential dangers of the following antibiotic medications. 

A large study showed erythromycin to increase the risk of sudden death due to an abnormally fast heart rhythm by 5 times when taken with other medications that can raise levels of erythromycin in the blood.

When only taking erythromycin, such incidences were still twice as high as the average person. 

In other words, you’re twice as likely to die suddenly from a rapid heart rhythm when taking erythromycin. And, you’re 5 times as likely to die from this same cardiac event when taking this antibiotic in conjunction with other (specific) meds. 

So then, what medications exacerbate the potentially fatal effects of erythromycin? 

The most common medicines that cause blood levels of erythromycin to raise are: 

  • Serzone, an antidepressant
  • Tao, an antibiotic
  • Crixivan, an anti-HIV drug
  • Nizoral, an antifungal medication
  • Diflucan, also an antifungal medication
  • High blood pressure or heart disease medications such as: 
    • Cardizem
    • Cartia
    • Dilacor
    • Diltia
    • Tiazac
    • Teczem
    • Calan
    • Covera-HS
    • IsoptinVerelanTarka

That’s a long list of meds and a lot of risk!

Erythromycin has been used for treating bacterial infections for more than 30 years. And, like most antibiotics, it has generally been considered safe with a minimal or low risk for adverse effects. 

Researchers say this risk, as detailed above, is still low among healthy individuals. And, as stated, the highest risk of death is when this antibiotic is taken with any of the medications listed above.

*Clarithromycin is a related antibiotic that has also been associated with an increased risk of “serious ventricular arrhythmias and an increased risk of sudden cardiac death.” 

Another common antibiotic that is known to cause sudden death due to a cardiac event is azithromycin. 

This particular antibiotic is the most widely prescribed antibiotic in the United States for the treatment of common bacterial infections. 

How high is the risk with azithromycin? 

According to a study published in JAMA, “compared to amoxicillin, azithromycin is associated with an 82 percent higher risk of death from cardiovascular causes within 5 days of exposure.” 

And, cardiovascular death isn’t the only risk, as there’s more than a 2-fold increased risk of death from other causes linked to this antibiotic as well. 

Azithromycin along with clarithromycin (briefly mentioned above) are known to “alter the normal flow of electricity within the heart,” here leading to deadly arrhythmias. 

Another study published in the New England Journal of Medicine found that taking a 5-day course of azithromycin increased the risk of death nearly 3-fold, with an 85 percent increase in the risk of death from all causes. 

Many other studies have corroborated these findings, with similar links found between azithromycin and cardiovascular-related deaths, serious arrhythmias, or heart attacks. 

Yet, some researchers still believe these findings to be inconclusive regarding this antibiotic as a few other studies state they’ve observed the opposite to be true of azithromycin, with the drug having no connection to cardiac deaths. 

Yet another antibiotic showing a link to cardiac death is levofloxacin. While there isn’t as much information available regarding this medication, the following has been observed: 

  • In a study on US veterans, “levofloxacin was associated with a 3.13 fold increased risk of cardiac arrhythmias, and a 2.49 fold increased risk of all-cause death when compared with amoxicillin.” 
  • This antibiotic has also been known to cause damage to the aorta, which can lead to death.

General Antibiotic Usage And Colon Cancer

While the above listed antibiotics have been shown to cause sudden cardiac death, the general use of antibiotics has also been linked to an increasing number of colon cancer cases in younger people. 

Colorectal cancer, though typically seen in older individuals, has been increasing in incidence in people below the age of 50. 

The British Journal of Cancer has identified this as being linked to antibiotic usage. 

As antibiotic usage increased over the years, researchers with similar inclinations put this exact notion to the test, and their findings do seem to back this link up.

When scientists observed data spanning nearly 12 years, in Scotland, they found that half of all participants with colorectal cancer had received a prescription for antibiotics. 

Researchers concluded the risk of colorectal cancer amongst those under 50 years of age was 49% higher with antibiotic usage.

Though these researchers have stated this link to not be causal, still doctors observing the study were surprised to see the risk associated with antibiotic usage at such a high percentage. 

Other studies have found both men and women taking antibiotics over the course of a 6 month period to be 17 percent more likely to develop cancer in the ascending colon than those individuals who did not take any antibiotics during that time frame. 


As we’ve detailed some grim statistics here, this information begs the question: Should I avoid antibiotics due to these troubling findings? 

Ultimately this is your decision, though most researchers concluded, no matter their findings, that healthy individuals were at little risk of developing the above-listed conditions. 

If you are concerned about antibiotic usage, consider the following recommendations to curb the overuse of these medications: 

  • When visiting your doctor due to illness for you or your child, ask your physician if the illness is bacterial or viral. Antibiotics will not fight off a virus and therefore they should not be taken in the case of a viral infection. 
  • If you are prescribed an antibiotic, take the full course of the medication to avoid reinfection, prompting the need for another antibiotic.
  • Do not take antibiotics for a period of time longer than what is prescribed. 
  • Do not take antibiotics prescribed to another family member. 
  • Stay healthy by eating a nutritious, balanced diet, remaining hydrated, getting adequate rest, and regularly exercising. Stay home when you’re feeling sick, so you don’t spread any type of infection. And, be sure to wash your hands regularly with soap and water. 


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