Why you should only use antibiotics if truly necessary

Four ways that antibiotics can cause real problems

Let’s be honest: most parents feel better when their sick child is prescribed an antibiotic.

There’s just something so reassuring about having a prescription. It’s hard to feel like all you can do is wait and give your child TLC; it feels better to do something. Even when the doctor says that your child has a virus, and explains that antibiotics treat bacteria, not viruses, it’s common for parents to think: but what if there is even a little chance that there is a bacterial infection along with — or instead of — the virus? It can’t hurt to be safe, right?

But that’s the thing: it can hurt. Here are four ways that antibiotics can cause real problems.


Allergies to antibiotics are common — and can develop in people who haven’t had them before. While most allergic reactions aren’t life-threatening, they can be.

Side effects

Side-effects are much more common than allergies. Lots of children get stomachaches, vomiting, diarrhea or all three. Babies often get diaper rashes from yeast when the antibiotics kill off the bacteria in the intestine that usually keep the yeast population in check. These side effects are completely worth it if you need to take the antibiotic, but not so worth it when you don’t, obviously.

Clostridium difficile

Speaking of killing off useful bacteria…the intestine is full of bacteria that help us stay healthy in all sorts of different ways. There are lots of different bacteria doing lots of different jobs—and as with yeast, they all grow together, making sure that no one strain starts growing out of control. When you take antibiotics, along with killing the bacteria doing bad things, you also kill off bacteria that were doing good things—like keeping other bacteria in check. One in particular, Clostridium difficile (or C. diff for short), can cause terrible diarrhea when it starts multiplying. C. diff infections can be hard to treat—the bacteria are tough little buggers—and are becoming increasingly common.

Antibiotic resistance

Bacteria, like all other living things, want to survive. Antibiotics get in the way of that survival, so bacteria quite understandably have been finding ways to fight back. By making small changes in their cells, they can make the antibiotics less likely to kill them.

Imagine the bacteria as soldiers on a battlefield fighting the molecules of antibiotics. Imagine if some of the bacteria were genetically different so that they had a special armor against the enemy. During the battle, the ones without the armor get killed — leaving behind the ones with the armor. That means that not only are the armored bacteria going to be the only ones on the battlefield next time—but they are the only ones around to make baby bacteria. Soon, all the bacteria have armor — and are undefeatable. Not only that, the undefeatable bacteria can spread to other battlefields (bodies) in all the usual ways bacteria spread.

Another important point is that it’s that battlefield experience that spurs the bacteria to make armor. If they aren’t fighting for their lives against antibiotic molecules, they don’t need to make any changes.

The more we use antibiotics, the more we end up making undefeatable bacteria. We call this problem antibiotic resistance. This is true for individual people—the more they take antibiotics, the more resistant their bacteria may become—and for the society as a whole.  Because we have been using antibiotics a lot (not just in medicines we give people, but in cleaning products and what we feed our livestock), we have a lot of resistance.  Already, people are dying from infections we can’t treat; if we aren’t more careful about how we use antibiotics, the problem will become much worse.

Again, it’s worth these risks if the antibiotics are definitely needed (although doctors need to choose antibiotics that target only the bacteria they want to kill). But it’s really not worth the risks if they aren’t.

The next time your child is prescribed antibiotics, ask if they are truly necessary. If the answer is yes, make sure your child gets every last dose. If the answer is no, say no thank you. And if you child isn’t prescribed antibiotics … please don’t ask for them.

About the blogger: Dr. Claire McCarthy is a primary care pediatrician at Boston Children’s Hospital, an assistant professor of pediatrics at Harvard Medical School, a senior editor for Harvard Health Publications and an official spokesperson for the American Academy of Pediatrics.