How Long Does it Take Amoxicillin to Work?

By Terez Malka, MD
Medically reviewed checkmarkMedically reviewed
December 14, 2021

Amoxicillin is an antibiotic used to help treat bacterial infections in both adults and children.

It’s been available for decades, and is one of the most commonly prescribed of all medications: More than 50 million prescriptions for amoxicillin are filled in the United States each year. 

When you start a new medication, it’s natural to wonder how long it will take to start working—so you’ll know when you’ll feel better.

In this article, I’ll tell you more about how amoxicillin works, and how fast it works.

I’ll also talk about when you should stop taking the antibiotic, the dangers of stopping too soon, and when to talk to your doctor or another healthcare professional.

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What is Amoxicillin?

Amoxicillin is in the class of penicillin antibiotics.

It is broad-spectrum, meaning it works on lots of different bacteria.

Amoxicillin is made by pairing an extra amino group with penicillin, which helps combat resistance to the drug. It works by inhibiting bacteria’s ability to grow.

Amoxicillin is not effective against viral infections like colds, COVID-19, or the flu

It will also not help most bronchitis and sinus infections, which are most often caused by viruses.

Sometimes secondary bacterial infections can occur after viral illnesses, and antibiotics may be needed.

Amoxicillin is often a first-line choice for this purpose.

If you are allergic to penicillin, you will likely be allergic to amoxicillin.

There are many different classes of antibiotics, and your doctor will make sure to choose one that is effective for your type of infection.

They will take your allergies, age, and other health-related factors into consideration when writing your antibiotic prescription.


Amoxicillin can be prescribed for many types of bacterial infections. Some common uses include:


Amoxicillin comes in a few forms.

Your doctor may prescribe it as a capsule, tablet, or a suspension (liquid).

Typically, people take amoxicillin twice to three times a day, or every 8-12 hours, either with or without food.

For adults, teenagers, and kids who weigh more than 88 pounds, the most common dose is 250-500 mg taken every eight hours, or 500-875 mg every 12 hours.

For children, doses range from 40-90 mg per kilogram of body weight, divided into 2-3 doses per day.

No matter how much you’re taking, aim to take your amoxicillin at the same time each day.

Your pharmacist or prescriber will give you dosing instructions and tell you exactly how to take your medication, including whether to take it with food.

Your medication should not be stored in a humid environment, like the bathroom.

Keep it in a cool, dry place out of sunlight.

Some medications may require refrigeration.

Ask your pharmacist if you have questions about how to take or store your medicine.

Infections that are not severe may be treated in as little as 3 days, but the typical course of treatment is 5-10 days.

Your prescription label insert will tell you how long you should take your amoxicillin.

If you forget to take a dose, do not panic.

If it has only been a few hours, take your dose and adjust your next ones accordingly.

If you are close to your next dose, skip your missed one and resume your schedule as normal. Never double up on amoxicillin doses.

Common Side Effects

Amoxicillin has some common side effects that are typical to many antibiotics. They may include:

More serious side effects can occur, though they are less common. If you notice any of these symptoms, discontinue your medicine and contact your doctor immediately.

  • Itching, hives, or rash
  • Wheezing or breathing problems
  • Skin blisters
  • Swelling of the lips, face, throat, tongue, or eyes
  • Stomach cramps
  • Severe diarrhea or bloody stools

This is not a complete list of possible side effects.

If you have questions or concerns while taking amoxicillin, ask your doctor or call your pharmacy.

How Fast Does Amoxicillin Work?

Amoxicillin starts addressing the bacteria that are causing your infection immediately, but you will not feel better immediately.

Amoxicillin will typically help you to start feeling better within a few days.

However, it may take up to 4-5 days before your symptoms improve.

When to Stop Taking Amoxicillin

Do not stop taking amoxicillin unless your prescription runs out or your doctor tells you to stop.

Even if you are feeling better, the medication still needs to finish addressing the bacterial infection.

Stopping early could lead to a resurgence of bacterial growth and could make them resistant to the next course of antibiotics.

If there is any amoxicillin leftover when you are done taking it, discard it.

Do not flush it down the toilet and do not save it.

It is considered to be expired and unsafe for use after 14 days.

Antibiotics should always only be taken for the specific purpose they were prescribed for.

Antibiotic Resistance

Bacteria have the ability to adapt to their environment.

Because of this, when they are threatened by antibiotics, they may be able to adapt and avoid being destroyed the next time they are exposed.

Much like viruses can mutate, bacteria can also evolve.

When bacteria evolve so that an antibiotic doesn’t work as well, the bacteria is considered “drug-resistant,” or antibiotic resistant.

Antibiotic resistance is a global health problem.

Millions of people are infected with drug-resistant bacteria each year.

In some cases, infections can be fatal.

The people primarily at risk of these superbugs are those who have a chronic illness or weakened immune systems, but everyone is technically impacted by potential risks.

You can reduce your risk of drug-resistant infections by only taking antibiotics when they are absolutely necessary and by taking them exactly as prescribed.

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Our physicians can prescribe antibiotics for various conditions, but only if necessary. Chat with a provider now.

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When to See a Doctor

You should see a doctor if you have been sick with a cold or flu but don’t seem to be improving after 7-10 days.

If your fever gets worse or other symptoms concern you, check in with a health care provider.

They may want to do some tests to determine if your illness is caused by a virus or bacteria. If a bacteria is causing your problem, you may not get better unless antibiotics are given to treat the infection.

How K Health Can Help

You can speak with primary care providers through K Health, without having to leave your home. Get peace of mind about your symptoms and, if needed, get a prescription.

Download K Health to check your symptoms, explore conditions and treatments, and if needed text with a provider in minutes. K Health’s AI-powered app is based on 20 years of clinical data.

Frequently Asked Questions

What should I do if I don't start to feel better after taking antibiotics?
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). If you complete your full course of antibiotics and do not feel better, check in with your healthcare provider. They will want to reevaluate you to determine the next steps in your care plan.
What dietary restrictions need to be in place when taking amoxicillin?
Amoxicillin does not have any specific dietary restrictions, unlike other types of antibiotics. Most doctors suggest avoiding alcohol while taking antibiotics, since it may impact how medication is absorbed. Alcohol also affects how your immune system works. When you are recovering from an infection, you want your immune system to be as strong as possible.
Can you make antibiotics work faster?
No. You cannot make antibiotics work faster, but you can do things to help your body recover from other symptoms of your infection. Stay hydrated, get plenty of rest, and eat regular meals to help your immune system work efficiently.
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Terez Malka, MD

Dr. Terez Malka is a board-certified pediatrician and emergency medicine physician.

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