Do antibiotics make you sleepy?
James Olson
Updated on May 18, 2026
If you're taking prescription antibiotics, you may feel tired and fatigued. This may be a symptom of the infection being treated by the antibiotics, or it may be a serious, but rare, side effect of the antibiotic. Learn more about how antibiotics may affect your body, and what you can do to counteract these effects.
Why do antibiotics cause fatigue?
One of the more common side effects of antibiotics is nausea, vomiting or diarrhea. As mentioned above, antibiotics sometimes kill the good bacteria in the body along with the bad, leading to stomach issues and possibly dehydration. So in this case antibiotics can make you feel sick and tired.What are the most common side effects of antibiotics?
The most common side effects of antibiotics affect the digestive system. These happen in around 1 in 10 people.
- vomiting.
- nausea (feeling like you may vomit)
- diarrhoea.
- bloating and indigestion.
- abdominal pain.
- loss of appetite.
What to avoid while on antibiotics?
Alcohol and caffeine.Consuming alcohol while on antibiotics may potentially increase blood pressure and can have other unpleasant side effects, such as headache and/or upset stomach. Some antibiotics can also cause caffeine to build up in the body.