Can antibiotics cause constipation?

Disclaimer: Please note that this article is research based and some of the views and findings do not conform with the CSN Diet.

Exploring the effects of antibiotics on the digestive system

Sometimes we have no choice but to rely on medication to save the day, only for side-effects to sabotage us in the end.

Antibiotics are celebrated for their ability to combat bacterial infections, but some doctors will suggest a probiotic or even just some yoghurt along with them.


Let’s investigate.

Can antibiotics cause constipation

An overview of antibiotics

In this day and age we are used to the idea of antibiotics and happily take them ourselves, and also administer them to our pets when prescribed. But what are they and what do they do?

Antibiotics are medications that either destroy bacteria or slow down their growth. It kills bacteria and prevents them from multiplying. 

Antibiotics can be taken orally, in the form of tablets, capsules or a liquid, but are also available as a cream, spray, ointment, eye drops or ear drops. 

For serious infections antibiotics can be injected or administered intravenously. 

The discovery of antibiotics brought on a drastic change in the field of healthcare. Before it became available in the 1940s, many people died from minor bacterial infections like strep throat.

For antibiotics to work properly, they need to be used correctly. Keep the following in mind:

  • Take your antibiotics exactly as your doctor instructs. He will tell you how many days you need to take them for, how many times per day and whether you should take them with food. Stick to this.
  • Don’t save some of your antibiotics for later use. This isn’t safe, you should only use them to treat the specific infection they were prescribed for.
  • Never take someone else’s medication or give your medication to another person. Prescription medication is tailor made for you and your specific needs.
  • You will usually receive the exact amount of antibiotics you need. Finish your medication even if you feel better, otherwise bacteria might survive and reinfect you.
    In the case that you have medicine of any kind left over, ask your local pharmacist about the safest way to dispose of it.

Today there is a growing concern for resistance to antibiotics. According to the Centres for Disease Control and Prevention, over two million illnesses annually occur in the USA because of antibiotics not working.

Even worse, around 23 000 lose their lives when these drugs don’t work. Why is this happening? As part of their natural evolution bacteria are constantly adapting their genetic makeup. 

These changes help them survive despite antibiotics being introduced into their environment. Another contributing factor is the overuse of antibiotics which leads to bacteria growing stronger.

Antibiotics should only be prescribed when they are needed, and this is not as simple as it sounds. Antibiotics clear up some bacterial infections, but not viral infections.

It might be that antibiotics sorted out your sore throat in no time on a previous occasion, and now the doctor won’t prescribe it again. This confuses patients and then they sometimes ask for antibiotics.

If the previous sore throat was the result of a bacterial infection, antibiotics were the correct treatment. If, this time, you have a viral infection, there is no point in giving you antibiotics.

Antibiotics will not work for viral infections such as colds, flu and most cases of bronchitis. Trust your doctor to determine whether you need them, in order to steer clear of overuse, which may leave you vulnerable.

Side effects of antibiotics

Like most types of medication, antibiotics cause side effects. These are mostly not a cause for concern and will resolve on their own once you stop taking the medication.

Common side effects include nausea, vomiting, cramps, diarrhoea, fever, sensitivity to light, vaginal yeast infection and tooth discoloration in young children.

Most prominent of these is the effect of antibiotics on the gut. As humans we have about 40 trillion microbes living inside our bodies. Most of these can be found in our gut.

While the idea of all these bacteria in our bodies is not a very pleasant one, it’s safe to say that they are friendly, working towards creating a balance in the body.

This impacts everything from how we digest our food to how we defend ourselves against outside threats such as viruses, parasites and harmful bacteria.

Unfortunately antibiotics can’t distinguish between good bacteria and bad bacteria. Therefore it can unintentionally kill off the good bacteria in our gut, hence causing intestinal side effects.

According to a study published in Nature two classes of antibiotics, tetracyclines and macrolides, wipe out good bacteria in the gut, leaving it open to gastrointestinal ailments and infections.

Infections from a type of bacteria known as Clostridiodes difficile are responsible for diarrhoea, nausea, fever, stomach pain, and in severe cases even death.

Tetracyclines are a type of broad-spectrum antibiotics, used to treat a variety of common infections – from acne to STDs. However, they also stop good bacteria from growing, and kill about half of good bacteria in the gut.

This wasn’t enough to convince the researchers that doctors should stop prescribing those kinds of antibiotics, and they started exploring ways to lessen the side effects instead.

Do antibiotics cause constipation?

In terms of gastrointestinal symptoms brought on by the use of antibiotics, you are much more likely to suffer from diarrhoea than from constipation. It is, however, not impossible to get constipated as well.

Whether you will suffer from constipation as a side effect will depend on the type of antibiotics you are using. But don’t automatically assume that your antibiotics are making you constipated.

There are actually a few different explanations for getting constipation while on antibiotics. 

Some people become constipated when they do not consume enough fluids, and some people do not drink as many fluids when they feel sick.

Fever also causes dehydration, and if you are on antibiotics it is possible that you are suffering from something that could give you fever.

If your constipation coincides with the exact time you are on antibiotics, it’s more likely that they are the cause.

Regardless of what has caused your constipation, there are a few things you can do to ease the symptoms: 

  • Don’t forget to drink enough water.
  • Ask your doctor about ways to manage your fever.
  • Include a lot of fibre in your meals.
  • Try to get some light exercise if your illness allows it. Rather stay away from heavy workouts.


If you have any concerns about gastrointestinal symptoms, the best thing you can do is discuss it with your doctor rather than follow your own head. 

Since there are many different types of antibiotics, things can go wrong. For example, some need to be taken on an empty stomach while others should be taken with food.

You will get the most out of your course of antibiotics by closely following the instructions on how to take them – and if all goes well you will feel better before you know it.



Hi, my name is Karien Nel and today I’m 37kg lighter than the day I started my weight loss journey with CSN Diet.

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