Do Antibiotics Make You Tired & Sleepy?


Antibiotics are medicines that treat bacterial infections. They either stop or completely kill off the harmful bacteria. Antibiotics, also called antibacterials, have saved many lives. They are used to treat illnesses such as respiratory tract infections (whooping cough, pneumonia), sepsis, and skin infections. Sometimes antibiotics are used to prevent illnesses, rather than treat them. This prophylactic use of antibiotics is especially prevalent before bowel or orthopedic surgery. Despite being so beneficial, antibiotics have many side effects. They even are said to shorten life span in certain instances. Because of these dangers, it is important to know exactly what these medications are, how they can affect you, and if they are the right solution to your problem. Some antibiotics in particular can make you tired and sleepy or weak. Although this side effect is said to be rare, this fatigue can seriously harm you in some ways. We will dive deep into the world of antibiotics to understand their history, benefits, side effects, and what to do if you feel tired from taking them. Understanding them in depth will give you a better idea if they are right for you.

How Antibiotics Work

As mentioned before, antibiotics stop or kill harmful bacteria in our bodies. It is normal to have a certain amount of bacteria. As bacteria multiplies, our immune systems usually kick in to fight and kill them. White blood cells go to battle with the multiplying army of bacteria and usually win. However, sometimes the amount of bacteria overpowers the strength of our immune system. This is where antibiotics come into play. Antibiotics work in one of two ways:

  1. Kills the bacteria: A bactericidal antibiotic, such as penicillin, destroys the cell wall or its contents. 
  2. Stops the bacteria from multiplying: A bacteriostatic inhibits bacterial protein synthesis.

It is important to be aware that though antibiotics work against many life-threatening illnesses, they do not work against viruses. For instance, antibiotics will not cure COVID-19 or upper respiratory tract infections (URTIs) like the common cold or flu. You must first determine whether the illness is bacterial or viral to determine the proper medication. If someone has coronavirus and also develops a bacterial infection as a complication, antibiotics can help cure the bacterial infection, but not the coronavirus. 

Antibiotics are used for treating bacterial infections, not viral infections.

Types of Antibiotics

Antibiotics have not been around all that long. The first natural antibiotic was penicillin, which was first discovered in 1928 by Sir Alexander Fleming of England. And the discovery happened purely by accident! Fleming, known to be a careless lab technician, had been experimenting with the influenza virus. While he was away for two weeks on vacation, upon his return he discovered mold had been growing on the staphylococcus culture. And the mold had prevented its growth. This accidental breakthrough changed the face of medicine as we knew it. At the time of the discovery, bacterial endocarditis, bacterial meningitis, and pneumococcal pneumonia were all fatal diseases. After the penicillin was discovered, these illnesses could be easily treated. And this group of drugs has continued to save millions of lives since the first discovery. Today penicillin-based antibiotics are still very much in use. Penicillin is, in fact, the most widely used antibiotic in the world.  Some common penicillin-based antibiotics include ampicillin, amoxicillin, and penicillin G. 

Antibiotics are diverse. There are many types of modern antibiotics and some that are still being invented today. Then there are also topical antibiotics in the form of over-the-counter ointments, lotions, and creams that are used for skin infections. Antibiotics can be taken orally in the form of liquids, tablets, or capsules. They can also be given by injection. Some antibiotics work for a broad spectrum of illnesses, while others treat a few specific bacterias. Some attack aerobic bacteria that need oxygen, while others attack anaerobic bacteria which does not need oxygen. Antibiotics are incredibly useful in that they are fast-acting. Some will even begin working within a few hours. This is so important when dealing with a quickly-spreading illness. As you can see, the convenience, diversity, and availability make antibiotics practically a miracle drug for the modern-day. But, we know that the effects of antibiotics aren’t all good. Let’s take a look at some of the downsides of antibiotics.

Which Antibiotics Can Make You Tired and Sleepy?

Feeling fatigued can happen when taking some antibiotics. This rare but potentially serious side effect occurs in some common antibiotics prescribed today. The exact reason as to why fatigue occurs in some individuals is still not known today. Some have speculated it is a result of the change in nutrient absorption or dehydration that occurs when the digestive system’s biome has been disrupted. Since the helpful bacteria have been wiped out, the body may become fatigued. However, not all antibiotics cause fatigue. We will discuss a few of the most common ones that do. And the side effect of sleepiness or tiredness is said to be relatively rare. Pay attention if you are taking the following medications and are feeling fatigued: 

  • Amoxicillin: Commonly going by the names Amoxil or Moxatag, amoxicillin is a highly effective penicillin antibiotic. It is typically used to treat bronchitis, pneumonia, and urinary tract infections (UTI), among other things. If you are feeling excessively tired or weak after taking amoxicillin, immediately contact your doctor. It may have affected your nervous system. It is normal to feel tired when taking this medication, but be cautious if you are feeling weak or faint or fighting to stay awake. Sulfamethoxazole (Bactrim) could be a helpful alternative to Amoxicillin. 
  • Azithromycin: Another common antibiotic with extreme tiredness as a side effect, azithromycin goes by the names Z-Pak, Zithromax, and Zmax. It is used to treat bacterial infections such as respiratory, skin, ear, and eye infections. It is also used against some sexually transmitted diseases. If azithromycin causes fatigue, talk to your doctor about clarithromycin (Biaxin) as an alternative. 
  • Ciprofloxacin: This is one of many fluoroquinolones and yet another antibiotic that can cause fatigue. Also known as Cipro or Proquin, ciprofloxacin is often used to treat infections of the skin, prostate, and bone, among others. Ciprofloxacin was first known as a cure for anthrax poisoning. Side effects can include dizziness, drowsiness, and being generally less alert. Another alternative to Cipro is Vibramycin (doxycycline), a tetracycline antibiotic. This is a good choice especially if you are allergic to penicillin. 

It is important to remember that everyone responds to antibiotics differently. Talk to your doctor about these potential side effects and if this medication is right for you. Make sure to inform him or her on other medications you are taking as well. You can also talk to your pharmacist about these potential side effects.

Other Possible Causes of Tiredness to Rule Out

It is important to first rule out that your fatigue is being caused by your illness, not the medication. Talk to your doctor about the symptoms of your illness to see if this could be a possibility. Also, be sure your doctor is well aware of any other medications you are taking. This is important information for your doctor to know because your antibiotic treatment could potentially react with other medications you are taking. Here are some other medications that antibiotics have been known to clash with:

  • Antacids
  • Antifungal drugs
  • Anti-inflammatory drugs
  • Muscle relaxants
  • Diuretics
  • Antihistamines
  • Blood thinners

When you talk to your doctor about what could be causing the fatigue, be sure to rule out your other medications themselves as well. They could have their possible side effects. Fatigue could also be a symptom of any treatments you may be under. Talk to your doctor in detail about your other medications and treatments. Determine whether they could be the culprit, rather than the antibiotics. Here is a list of a few other medications and treatments that can cause you to be tired and sleepy:

  • Blood pressure medication
  • Antidepressants
  • Anti-anxiety medication
  • Radiation therapy
  • Chemotherapy
  • Heart drugs
  • Pain drugs
  • Antihistamines
  • Cough medications

One last to consider is whether or not you are taking your medications properly. To reduce side effects, ask yourself the following questions to make sure you are properly taking your prescribed antibiotic medications:

  • Am I taking the antibiotics as directed? Some antibiotics should only be taken with water. And some are supposed to be taken with a meal. Make sure you are taking yours when directed. 
  • Have I taken the whole course of antibiotics or stopped short? You should be finishing the course of antibiotics, even if the symptoms have cleared up.
  • Am I taking the correct dosage? So it is wise to pick and choose in your life when taking them will be most beneficial for your health.
  • Am I abstaining from alcohol?
  • Am I taking a probiotic? Research shows that people taking a probiotic will reduce their chance of getting diarrhea by 42%.
  • Have I notified my doctor about my side effects? Keep your doctor informed of any changes that have occurred since you’ve taken the medication, including sleepiness, diarrhea, and mood changes.  

What to Do if You Feel Tired and Sleepy From Antibiotics

So you have at this point ruled out other medications and treatments as being the culprit. You are sure that the fatigue is not caused by the illness or other medicinal interactions. Now it is time to determine if the antibiotics are making you tired. Perhaps you are at a point where fatigue is keeping you from doing your job correctly. Or maybe you are unable to focus when driving. Perhaps you are unable to do your normal favorite activities due to being drowsy. Drowsiness significantly increases your risk of falling or getting into a car accident. You could find yourself being permanently injured due to this side effect. If you do end up feeling tired and sleepy from the antibiotics, what do you do? The one thing you shouldn’t do is immediately stop the medication. This may allow the infection to worsen and can also lead to antibiotic resistance. If you just started to take the medication and the fatigue doesn’t fade within the first couple of days, or it gets worse, here are a few things we recommend to do:

  • Talk to your doctor about potentially switching to another medication, or trying a different dosage. 
  • Do not drive or do any activities that require your full attention and focus. You could potentially cause yourself or others harm. Avoid these things until you know exactly how the antibiotics are affecting you.
  • Do not drink alcohol, particularly when taking metronidazole (Flagyl)or trimethoprim-sulfamethoxazole (Bactrim). The combination will cause many other unpleasant side effects.
  • Avoid any other substances that make you sleepy.
  • Be sure to be getting enough sleep.

The Case Against Antibiotics

Not only can antibiotics make you sleepy, but there are many other potential side effects of antibiotics. There is a long list of serious side effects for each medication. You need to determine whether the potential side effects are worth the benefits of the medication. Here are a few other common side effects that occur with antibiotics:

  • Digestive problems (diarrhea, nausea, vomiting, abdominal pain)
  • Headaches 
  • Sensitivity to the sun
  • Photosensitivity
  • Depression 
  • Anxiety
  • Fungal infections, such as yeast infections
  • Allergic reaction; sometimes life-threatening (rash, hives, anaphylaxis, shortness of breath)

Besides the potential side effects, one must consider when taking antibiotics the overall health of the person. Because of the bacteria-killing nature of antibiotics, bacteria can be completely wiped from your body. This includes not only the bad bacteria but the good bacteria as well. This leaves your body easy prey to an infection that could take a toll on your health. One example is the bacterium called clostridium difficile. C. difficile typically develops after antibiotic treatment and can cause anything from diarrhea to life-threatening inflammation of the colon. This is due to the destruction of the normal, helpful bacteria from the treatment. And taking antibiotics often can cause your body to develop a resistance to them in general. Additionally, keep in mind that antibiotics mostly work well for short-term use. In most people, new good bacteria develop quickly afterward to balance the immune system. But you must consider the consequences of using a course of antibiotics for long-term treatment. The longer the course of treatment, the more damage is being done to your immune system.  So it is wise to pick and choose in your lifetime when to take them, and what times will be most beneficial for your health.

It’s important to always follow the prescribed dose with antibiotics.

Effects of Overprescription & Misuse

It is imperative that if you are to take antibiotics that you understand all the risks involved. Some of the common problems associated with antibiotics are caused by their overprescription or misuse. Antibiotics are very much overprescribed these days. And due to the overuse or misuse of these medications, the number of bacterial infections is growing. The CDC reports that more than 2.8 million infections occur every year that are resistant to antibiotics. Sadly, 35,000 people in the United States die yearly as a result. The infections have become resistant to antibiotics due to the bacterium’s improved defenses. This was predicted by Alexander Fleming, the discoverer of penicillin. Only take the antibiotics when they are prescribed, and follow the dosage and label instructions. Make sure the antibiotic has been approved by the FDA. If you stop taking your antibiotics before the illness is completely gone, the surviving bacteria may build a resistance to the medication. Then the bacteria will be resistant to the antibiotic in the future due to previous exposure. Do not simply stop the medication when your symptoms improve. It is also important to pay attention to when to take the medication, and what foods or drinks you can have while on it. Following these instructions could determine whether the medication works for you or not. 

Do not be afraid to question your doctor and ask for alternative medicines if you think antibiotics are not right in your case. About 30% of antibiotics prescriptions (47 million prescriptions) are prescribed unnecessarily. Oftentimes bacterial infections get better on their own. Particularly antibiotics aren’t really necessary for many sinus infections, and some ear infections. It might also be helpful to talk to a pharmacist with a PharmD to direct you in the right direction. Although pharmacists cannot prescribe the right antibiotics for you, they have a wealth of knowledge about dosage and side effects that can be just what you need to know.

With Antibiotics, Knowledge is Power

Antibiotics can be a double-edged sword. After their surprise discovery in 1928, they have impacted so many people’s lives. Some for the better, and some for the worse. While saving many people’s lives over the years, they have also included some damage in the way of side effects. The destruction of bacteria has left some immune systems devastated, and sometimes unable to recover. The lingering side effects also sometimes cause their problems that can send your health into a tailspin. Now you know a little bit more about antibiotics and the influence they have on your body and overall health. We hope you or your caregiver use this information to make the right informed decision for you. We are here for you. For more information on antibiotics, their side effects, and finding what works for you or your loved ones, please visit

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