Antibiotics can make you tired, and it happens to many people. You may feel unusual fatigue (deep tiredness) or low energy while on antibiotics. This happens because the medicine not only fights infection but also affects gut bacteria, nutrient levels, and your immune system’s balance. Amoxicillin side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances. Amoxicillin is also used to treat tonsillitis and pharyngitis (sore throat). Amoxicillin belongs to the group of medicines known as penicillin antibiotics. It works by killing the bacteria and preventing their growth. However, this medicine will not work for colds, flu, or other virus infections. Although they don’t affect everybody in the same way, some antibiotics may have a side effect of tiredness. Learn about all the potential side effects of antibiotics and what you can do about it. While fatigue is not the most common side effect of antibiotics such as amoxicillin, cephalexin or azithromycin, some people do notice extra sleepiness, sluggishness or a general sense of low energy while taking these medications. Antibiotics are safe, effective and generally well-tolerated. Fatigue felt while taking them is likely the illness itself, and not a side effect. Antibiotics like amoxicillin don't usually cause tiredness, but some people may feel fatigued during treatment. This fatigue can be due to the infection itself or other factors. Amoxicillin itself is not a sedative, but the process your body undergoes while on it can definitely lead to fatigue. Your system is waging a massive energy war on two fronts: fighting off the original bacterial infection and adjusting to the powerful medication. No, amoxicillin itself won’t make you tired. It’s not listed under adverse reactions for any of the current prescribing information. That doesn’t mean you won’t feel tired while taking amoxicillin. It’s just that you shouldn’t blame the antibiotic. Official answer: Amoxicillin is not known to commonly cause tiredness or fatigue in most people, but some individuals do report feeling.