Why do I feel worse after starting antibiotics?
Ava Arnold
Updated on March 12, 2026
While taking an antibiotic may make you feel like you're doing something to get better, it's not helping at all.” In fact, taking antibiotics may make you feel worse. Like every other drug, antibiotics can have bad side effects, including severe diarrhea and serious allergic reactions.
Can symptoms get worse after starting antibiotics?
Depending on the severity of your infection, if you are feeling worse after one to two days of taking antibiotics, or less time if you have worrying new symptoms, you should go back to your doctor. Preferably it should be the one you saw the first time.Why do I feel sick after starting antibiotics?
The gut microbiome keeps the digestive system functioning and helps the immune system to defend against viral infection. When antibiotics upset the bacterial balance, a person may experience side effects, such as nausea or diarrhea.Can antibiotics make infection worse?
They can cause bacteria to become increasingly resistant to treatment, for example, and destroy healthy flora in the gut. Now, a new study from Case Western Reserve University shows that antibiotics can damage immune cells and worsen oral infections.How long after starting antibiotics should I feel better?
Antibiotics begin to work right after you start taking them. However, you might not feel better for 2 to 3 days.The Dos and Don’ts for Taking Antibiotics
Do antibiotics make you worse before better?
While taking an antibiotic may make you feel like you're doing something to get better, it's not helping at all.” In fact, taking antibiotics may make you feel worse. Like every other drug, antibiotics can have bad side effects, including severe diarrhea and serious allergic reactions.Can antibiotics make you feel sick and tired?
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.How do I know if my antibiotics are working?
Antibiotics can take a few days before they start to work, so you may need to wait 3-5 days before you notice improvements. Depending on the infection, it may take longer to feel fully better (like with bacterial pneumonia).How do you stop feeling sick when taking antibiotics?
How to Reduce the Side Effects of Antibiotics
- Take Antibiotics as Directed. Some antibiotics should be taken only with water. ...
- Take All of the Antibiotic Prescription. You should finish the entire prescribed course of antibiotics, even if your symptoms clear up. ...
- Abstain from Alcohol. ...
- Take a Probiotic. ...
- Talk to Your Doctor.
What should I do if antibiotics don't work?
If you have an infection that is antibiotic-resistant, your healthcare provider may or may not have other treatment options. Taking unneeded antibiotics promotes the growth of resistant bacteria. Practice good hygiene. It helps prevent the spread of infections that are resistant to antibiotics.Can antibiotics make you feel weird?
But despite their ability to treat potentially dangerous infections, many people can experience uncomfortable side effects when taking antibiotics, including bloating, indigestion, nausea, and vomiting. Though less common, some antibiotics can also make you feel tired or weak.Can antibiotics make you feel like you have a cold?
Since antibiotics can only treat sicknesses caused by bacteria, they won't help you feel better if you have flu symptoms. In fact, in many cases, taking antibiotics for the flu can make you sicker or make your sickness last longer.How long do antibiotics take to start working?
"Antibiotics will typically show improvement in patients with bacterial infections within one to three days," says Kaveh. This is because for many illnesses the body's immune response is what causes some of the symptoms, and it can take time for the immune system to calm down after the harmful bacteria are destroyed.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.