The Hidden Threat of Drug-Resistant Bacteria: Why Antibiotics Don’t Belong in Cold Treatments

The number of deaths from infections caused by drug-resistant bacteria exceeds 8,000 per year with estimates suggesting it could become the world’s leading cause of death!

Even after the COVID-19 pandemic, a wide variety of infectious diseases continue to spread around the world.

In Japan, the number of pertussis (whooping cough) cases has surged this year. It’s also been pointed out that in this outbreak, strains resistant to macrolide antibiotics — the standard treatment — are increasing.

In fact, in recent years, the rise of drug-resistant bacteria that no longer respond to antibiotics has become a major global problem.

While various countries are working on countermeasures, Japan formulated its Action Plan on Antimicrobial Resistance (AMR) in 2016 and has been promoting AMR measures ever since.

Antimicrobial drugs, commonly called antibiotics in the medical field, have long been widely used to treat bacterial infections.

However, if antibiotics are used inappropriately — for illnesses not caused by bacteria, or if patients stop taking them partway through treatment — there’s a risk that drug-resistant bacteria can multiply inside the body. As these bacteria increase, infections that were once treatable with ordinary antibiotics may no longer respond, raising the risk of serious illness or even death.

At present, in Japan alone, over 8,000 people die each year from infections caused by drug-resistant bacteria. If no effective measures are taken, it’s estimated that by 2050, 10 million people could die annually worldwide from such infections — making it the leading cause of death globally.

The situation is becoming extremely serious.

Antibiotics (antimicrobial drugs) do not work against colds caused by viruses

To prevent the spread of drug-resistant bacteria, it’s essential not only to thoroughly implement infection control measures but also to use antibiotics properly in order to avoid increasing resistant strains. Patients, too, need to understand that antibiotics should be used for appropriate diseases, in the correct type, dosage, and duration.

According to a 2024 survey by Japan’s AMR Clinical Reference Center, which leads the country’s AMR countermeasures, 39% of people mistakenly believed that “antibiotics work for colds,” and 35% answered “I don’t know.” Unfortunately, this shows that many people still don’t properly understand how antibiotics should be used.

Among those reading this article, there are likely quite a few people who believe that antibiotics work for colds, or who have taken them after being prescribed by a doctor.

But most colds are caused by viruses. Antibiotics are medicines that work against bacteria. Because viruses and bacteria are fundamentally different in how they function, antibiotics cannot treat colds. In other words, taking antibiotics for a cold is meaningless.

Dr. Shugo Sasaki of the AMR Clinical Reference Center explains:

“A cold is an illness where, regardless of whether you have a fever or not, you experience some combination of symptoms like a runny nose, sore throat, or cough. These symptoms are caused by inflammation of the mucous membranes in the nose, throat, or bronchial tubes, and in most cases, the culprit is a virus.

On the other hand, antibiotics are medications that either kill bacteria or suppress their growth — in other words, they’re treatments that work on bacteria. They don’t work for colds caused by viruses.

When a doctor diagnoses a cold, they prescribe medications to ease the symptoms — for example, a painkiller for a sore throat or cough suppressants for a bad cough. The idea is to relieve the patient’s discomfort, let them rest, and wait for the body’s immune system to overcome the infection on its own. That’s the proper way to treat a cold.”

However, in the past, it was routine for antibiotics to be prescribed when visiting a medical facility for a cold. According to Dr. Sasaki, many doctors didn’t have much awareness about drug-resistant bacteria, and it was common practice to prescribe antibiotics as an infection treatment even for colds.

“At the AMR Clinical Reference Center, we’re actively conducting educational and awareness campaigns for healthcare professionals, and infectious disease education is gradually being incorporated into medical institutions as well. In fact, survey results show that the proportion of doctors prescribing antibiotics for colds has decreased.

That said, we’re still only halfway there — some doctors continue to prescribe them. Figuring out how to approach those physicians is a challenge we must address moving forward,” says Dr. Sasaki.

Many doctors diagnose colds based solely on hearing the patient’s symptoms!?

The author recently had such an experience as well.

Since the author has an immune system-related chronic condition, whenever symptoms of a cold appear and there’s concern about COVID-19 or influenza, they visit a nearby internal medicine clinic. Yet twice last year, both times they were prescribed antibiotics.

The first time, with a fever and cough, the doctor didn’t even check the author’s throat or use a stethoscope. He simply declared, “It’s bronchitis. I’ll give you fever medicine and antibiotics,” making an instant diagnosis. Feeling unwell, the author reluctantly accepted the prescription and went home, but couldn’t quite agree with the decision. While aware of the risks of self-diagnosis, they chose not to take the antibiotics — and by resting, recovered after ten days.

On the second occasion, visiting for a severe sore throat, a different doctor examined the throat and said, “It’s probably a cold, but just in case, I’ll prescribe antibiotics.” Frankly, the author had expected that as long as COVID-19 and influenza were ruled out, a painkiller would suffice — so this came as a surprise.

Having previously had an allergic reaction to antibiotics, the author strongly voiced concern about taking them, only to be met with, “Then I’ll prescribe a different medicine,” as the doctor remained insistent. Uncomfortable with the idea of taking antibiotics just in case, the author persisted and finally managed to get only a painkiller prescription. In that case, recovery came in four days.

In fact, one reason for prescribing antibiotics as a precaution or just in case is the difficulty of determining whether a patient’s symptoms are caused by a virus or bacteria within a short consultation time.

“One of the ways to determine the cause is through a medical interview. The doctor checks the interview sheet and examines the patient directly — listening to chest sounds with a stethoscope, checking the throat, and feeling for swollen lymph nodes to make a comprehensive assessment.

However, in reality, many doctors likely rely on hearing symptoms like, ‘My nose is stuffy, my throat started hurting, and I developed a fever today,’ and based on their own experience, conclude it’s a cold. At that point, since it’s not clear whether the cause is a virus or bacteria, some doctors prescribe antibiotics just in case,” the explanation goes.

Prescribing antibiotics just in case carries more disadvantages than benefits

However, the likelihood that antibiotics prescribed just in case will actually be effective is extremely low.

“There’s a slight chance that an illness which seems like a cold could turn out to be a bacterial infection where antibiotics would work — but that’s very rare.

On the other hand, the probability of experiencing side effects from antibiotics is much higher. These can include allergic reactions, diarrhea, nausea, and other symptoms. In rare cases, serious side effects like liver or kidney damage, or arrhythmia, may occur. Considering this, the disadvantages of prescribing antibiotics just in case far outweigh any potential benefits.

In Japan’s healthcare system, if a patient doesn’t recover after resting, they can come back for a follow-up visit. At that point, the doctor can properly assess whether antibiotics are necessary. Prescribing them preemptively should be avoided.

There are also cases where doctors prescribe antibiotics because patients request them. While this is done out of consideration for the patient’s feelings, it’s more important for doctors to carefully explain the disadvantages of unnecessary antibiotic use and communicate properly,” explains Dr. Sasaki.

Additionally, among patients, even when antibiotics are appropriately prescribed by doctors, some stop taking them midway or don’t follow the prescribed dosage and frequency — like taking a medication meant for three times a day only once. This too is an example of improper antibiotic use.

“There are many kinds of bacteria in the human body, and when antibiotics are administered, they also kill bacteria unrelated to the illness. Of course, if it’s a confirmed bacterial infection, the benefits of antibiotics outweigh the risks, so this isn’t a problem.

But if antibiotics are given for viral infections or other cases where they aren’t needed, there’s no benefit — and only drug-resistant bacteria survive. And with no competition, these resistant strains multiply within the body.

Moreover, if you stop taking antibiotics partway through, the remaining drug-resistant bacteria are more likely to survive and multiply, and the illness itself may relapse.

If you don’t take the proper amount or frequency, the concentration of the drug in your body won’t reach effective levels, creating a situation where it aggravates the bacteria without killing them. As a result, bacteria are more likely to develop resistance to the antibiotic.

So using antibiotics for illnesses where they aren’t indicated, or not following the proper dosage, duration, and frequency, greatly increases the risk of nurturing drug-resistant bacteria inside the body.”

It’s essential for doctors and patients to communicate clearly in order to use antibiotics appropriately — yet, the author admits that even when prescribed antibiotics for bronchitis or a cold, they hesitated to question the necessity, out of fear of being thought of as a meddlesome layperson.

Dr. Sasaki offers this advice:

“I understand that it can be difficult for patients to question a doctor’s prescription. In that case, how about asking, ‘What kind of effect does this antibiotic have?’ Or you might say, ‘I’ve read about drug-resistant bacteria and I’m a bit concerned.’ If the doctor still believes the prescription is necessary, they should properly explain the reason.

Another option is to consult the pharmacist at the pharmacy. If you tell them, ‘I’m not sure why I was prescribed this antibiotic,’ they’ll likely give you a clear explanation — and in some cases, the pharmacist might even contact the doctor for clarification on your behalf.”

Drug-resistant bacteria spread from person to person

When drug-resistant bacteria multiply inside the body, how do they cause an infection?

“We don’t know exactly when the drug-resistant bacteria present in the body will turn harmful and cause an infection.

Infections occur when invading pathogens (viruses or bacteria) multiply and battle against the body’s immune system — sometimes nothing happens, and other times they trigger an infection. Simply put, if your body is weakened, you’re more likely to develop an infection if bacteria enter, while if you’re healthy, it’s less likely.

Even if drug-resistant bacteria increase inside the body, for young and healthy people, they usually won’t cause any immediate problems. However, 20 or 30 years from now — if you become older or fall ill and your immunity declines — those lingering drug-resistant bacteria might cause an infection. And since these bacteria are difficult to treat, the infection could become severe.”

In short, the more drug-resistant bacteria a person carries, the higher their risk of developing infections caused by them — and the fewer you carry, the lower your risk.

To avoid increasing drug-resistant bacteria, proper antibiotic use is essential.

Another crucial point to remember is that drug-resistant bacteria spread from person to person, and from people to their environment. Preventing the spread of drug-resistant bacteria requires rigorous infection control measures to stop them from passing between people.

“If drug-resistant bacteria enter the bodies of the elderly or people with weakened immune systems, their risk of developing an infection is higher than in healthy people — making it dangerous. Some drug-resistant bacteria can also survive for extended periods on the skin or on environmental surfaces such as doorknobs, handrails, and tables. If infection control measures aren’t thorough, they can easily spread to others nearby.

Hospitals are particularly high-risk environments for the spread of drug-resistant bacteria. For example, MRSA (methicillin-resistant Staphylococcus aureus) — a drug-resistant bacterium long recognized as a problem within hospitals — can linger on the skin for extended periods and be difficult to eliminate. This allows it to spread via medical staff from one patient to another during examinations, potentially causing hospital outbreaks.

To prevent the spread of drug-resistant bacteria, strict infection control and proper antibiotic use are essential. It’s important that more people recognize that these pathogens pose risks not only to themselves but also to those around them. Each of us needs to make an effort to avoid increasing the number of drug-resistant bacteria.”

(1) Antibiotics: A general term for drugs used in medical care that act against bacteria. Commonly known as antibiotics or antimicrobial agents.

Dr. Shugo Sasaki
Physician at the AMR Clinical Reference Center, National Center for Global Health and Medicine Crisis Management Research Institute. Graduated from Keio University School of Medicine in 2008. Worked in infectious disease care at Yokohama City Citizen’s Hospital, Tokyo Metropolitan Komagome Hospital, and Saitama Medical University Hospital. Earned a master’s degree from the Liverpool School of Tropical Medicine. Completed the Ministry of Health, Labour and Welfare’s IDES training program. In his current post since 2024, engaged in education and public awareness activities regarding antibiotic resistance.

■ The AMR Clinical Reference Center official site is [here].