Buzz
If you've been battling a cough and a runny nose for several days, you might visit your doctor hoping for something to alleviate your symptoms. However, if your cold is caused by a common virus (or even a tougher one like COVID or the flu), antibiotics won't be of any help. Here's why.
Viruses Are Not the Same as Bacteria
Let’s take a quick biology detour, but I’ll keep it short. You’re familiar with how your body is made of cells, right? These tiny sacs of fluid, each containing DNA, a mitochondrion (the “powerhouse of the cell”), and other components? Well, bacteria are free-living organisms that consist of just one cell, and it's smaller than most of ours. (Fun fact: They have DNA, but no mitochondria.) Certain diseases are caused by bacteria, such as salmonella, gonorrhea, Lyme disease, and strep throat.
Then there’s a different, even smaller type of germ: viruses. These tiny invaders are much smaller than bacteria, and they’re so simple in structure that they’re not even classified as cells. Some viruses are small enough to infect bacteria themselves.
Humans also suffer from viral diseases like COVID, the flu, RSV, measles, HIV, and rabies. By the way, there’s no easy trick to distinguish between bacterial and viral infections—you’ll need to memorize (or look up) each one. However, most common “colds” are viral.
Antibiotics Only Target Bacteria
What we commonly refer to as “antibiotics” are actually antibacterial drugs. Examples include penicillin, amoxicillin, Z-Pak, doxycycline, and ciprofloxacin—frequent go-to medications for bacterial infections.
Each antibacterial drug works by targeting something unique to bacteria, like disrupting a process necessary for their survival and reproduction, which humans don’t rely on. (Of course, if a drug affected processes in our bodies, it would harm us as well. This is why chemotherapy for cancer is so harsh: it poisons our own cells.)
For instance, penicillin works by breaking down the cell walls of bacteria. Tetracycline attaches to the ribosomes—protein-making enzymes—but only in the version used by certain bacteria. If you’re dealing with a viral infection, these antibacterial treatments won’t have any effect on the virus.
Why Doctors Won’t Prescribe Antibiotics ‘Just in Case’
When you visit urgent care with a bad cough, your healthcare provider will try to determine what kind of illness you might have. They could perform a COVID test, a strep test, or a flu test, among others. They’ll also assess your symptoms and medical history (such as how long you’ve had the cough) to help pinpoint the issue. And yes, sometimes it turns out you have a bacterial infection. Or you may have initially had a viral illness, but then developed a secondary bacterial infection—because bacteria often strike when our immune systems are weakened. If your illness is bacterial, antibiotics would be necessary.
However, in many cases, a virus is simply a virus. Most common colds are caused by viruses such as rhinoviruses, adenoviruses, RSV, and non-COVID coronaviruses, which are frequent culprits behind a cough and runny nose. Your doctor doesn't even need to identify which specific virus is causing your symptoms because the treatment remains the same for all: rest, hydration, and time.
Not only do antibiotics fail to treat viral infections, but they can also have negative side effects. For one, they affect your body’s beneficial bacteria, like those in your gut. If you've ever experienced diarrhea while taking antibiotics, you know exactly what I mean. In some cases, antibiotics can even lead to life-threatening gastrointestinal infections like C. diff.
Another drawback of unnecessary antibiotic use is that it can accelerate the spread of antibiotic-resistant bacteria, a growing issue worldwide. One reason C. diff is so difficult to treat is its resistance to antibiotics. The same is true for MRSA, or methicillin-resistant Staphylococcus aureus. When we use antibiotics, we often kill off bacteria that are not resistant, which creates opportunities for resistant bacteria to proliferate.
Finally, there’s always the risk of an adverse reaction to any medication. You might have an allergy to a specific antibiotic, or you could experience side effects, which can range from minor discomforts like stomach cramps to more severe issues. Therefore, it’s best to avoid taking antibiotics unless absolutely necessary.
