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How Long Do Antibiotics Take To Work?

Andrew Bellingham

Andrew Bellingham

Pharmacist | 20+ Years | BPharm | Dip Clin Pharm

Antibiotics are powerful medications that are used to treat infections caused by bacteria. While they can be highly effective in combating these infections, it is important to understand how long it takes for antibiotics to start working and the factors that can impact their effectiveness.

Note: this article is focused on how long it takes for antibiotics to have a noticeable effect, not to inform you when you may be fully fit.

What affects how long antibiotics take to work?

There are a number of factors that can impact the length of time it takes for antibiotics to start working and be effective in treating an infection. These factors include: 

  • Type of infection being treated: Different types of infections can require different lengths of treatment with antibiotics. Mild infections, such as a UTI, may respond more quickly to treatment than more severe infections.


  • Type of antibiotic being taken: Different infections require different treatments, with some working more quickly than others.
  • Overall health of the patient: Individuals with compromised immune systems or other underlying health conditions may take longer to respond to treatment than those who are otherwise healthy. 

Average Length of Time for Antibiotics to Start Working

Mild Infections: 1-3 days

For most mild infections, like a sinus infection, you will begin to feel better within 1-3 days of starting your antibiotic treatment.

Moderate to Severe Infections: 3-7 days

With more severe infections, like pneumonia, also falling under this category, some improvements are seen within 3-7 days. 

However, these more severe infections are likely to require a longer course of treatment to be fully resolved. 

Chronic Infections: Longer than 7 days

Chronic infections, like bone infection or chronic sinus infection, may take longer to treat than less severe infections, and may require a longer course of treatment to resolve completely.

Tips for Maximising the Effectiveness of Your Antibiotics

If you’re reading this and already taking antibiotics, or are about to begin your treatment, read through this section to find out how you can maximise the effectiveness of your treatment and start feeling better sooner. 

  • Take the full course of treatment (even if you begin to feel better): Stopping your treatment early can lead to the development of antibiotic resistance, which can make it more difficult to treat future infections. 

  • Take your antibiotic at the same time each day: Ensure your body has a consistent level of medication, and your treatment will work as effectively as possible. 

  • Avoid alcohol: Alcohol can interfere with how antibiotics work in the body, and reduce their effectiveness.

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