How Long Does Amoxicillin Stay in Your System? Plus, 8 More Amoxicillin FAQs

Amoxicillin (Amoxil) is a popular penicillin antibiotic. It’s used to treat a variety of bacterial infections, such as strep throat, skin infections, and sinus infections.

If you’ve recently been prescribed amoxicillin, you may be wondering what to expect. One common question is: How long does amoxicillin stay in your system?

Here, we’ll answer this along with eight other frequently asked questions about amoxicillin.

1. How long does amoxicillin stay in your system?

After you take a dose of amoxicillin, it’s rapidly processed by your kidneys. For most people, amoxicillin stays in the body for about 8 hours after a dose.

A little more than half of amoxicillin is removed by your kidneys within 6 to 8 hours. Then the remaining amoxicillin is slowly cleared by your kidneys over the next few hours.

But how long amoxicillin stays in your system can vary from person to person. Factors that may affect how long it lasts include:

• Kidney function: If your kidneys don’t work as well as they should, they might clear amoxicillin more slowly, meaning the medication will stay in your body longer.

• Age: Older adults and newborns (children ages 3 months and younger) are more likely to have lower kidney function. As a result, it may take longer for them to clear amoxicillin.

• Hydration: Amoxicillin leaves the body mainly through urine. If you’re dehydrated, your kidneys may have a harder time clearing amoxicillin.

Certain medications can also affect how your kidneys remove amoxicillin. For example, probenecid blocks your kidneys from getting rid of amoxicillin. This can cause amoxicillin levels to stay higher for longer. In fact, probenecid is sometimes prescribed with amoxicillin to help amoxicillin fight infections better.

Good to know: Amoxicillin dosages can be based on body weight, especially for children who weigh 40 kg (88 lbs) or less. This helps make sure they receive an appropriate dose. But body weight may not have as much of an effect on how long amoxicillin stays in the body. One small study found that when amoxicillin is dosed appropriately for adults considered to be obese, body weight does not significantly change how quickly it’s cleared. Kidney function plays a bigger role in how long amoxicillin stays in your body.

2. How long does it take for amoxicillin to work?

Amoxicillin starts to fight your infection soon after you take your first dose. But that doesn’t mean you’ll feel better right away. You may start noticing an improvement in your symptoms within 2 to 3 days. How long it takes to feel completely better depends on the type and severity of your infection.

Even if you start feeling better after a few days, keep taking amoxicillin for the full length of time prescribed. Stopping treatment early could mean your infection won’t be fully treated. A long-term consequence of not completing your course could be antibiotic resistance. This occurs when bacteria change in ways that antibiotics no longer work.

If your symptoms aren’t improving or they get worse during treatment, reach out to your prescriber.

3. How long do you have to take amoxicillin?

In most cases, amoxicillin courses last 5 to 10 days. But some people take it for up to 14 days (2 weeks). How long you have to take amoxicillin depends on your infection type and how serious it is.

Below is a chart with the recommended treatment length of amoxicillin for common, mild infections. Your healthcare professional will determine your dosage based on your personal infection needs. Always take amoxicillin as prescribed.

4. Should you take amoxicillin with food?

You can take amoxicillin with or without food. But stomach-related side effects, such as nausea, vomiting, and diarrhea, are common with amoxicillin. So taking it with food may help prevent these side effects.

Most adults and children take amoxicillin two or three times per day, depending on the prescribed dose. If your dosing schedule lines up with mealtimes, you can use your meals as a reminder to take each dose.

5. Should you take amoxicillin separately from other medications or substances?

Certain medications and substances may interact with amoxicillin. These interactions may affect how well either medication works or increase the risk of certain side effects.

Some medications and substances that can interact with amoxicillin include:

• Gout medications, such as allopurinol (Zyloprim)

• Blood thinners, such as warfarin (Coumadin, Jantoven)

• Other antibiotics, such as doxycycline (Oracea)

• Alcohol

Certain live travel vaccines, such as the cholera vaccine (Vaxchora) or typhoid vaccine (Vivotif), should be separated from amoxicillin too. When taken together, amoxicillin may cause them to not work as well. Vaxchora should be taken at least 14 days (2 weeks) apart from amoxicillin. Vivotif should be taken at least 72 hours (3 days) apart from amoxicillin. Ask your pharmacist or prescriber how long you should wait between taking amoxicillin and receiving a live bacterial vaccine.

Be sure to give your healthcare team an up-to-date medication list so they can look for potential interactions. This will help them decide if you need to make any changes to your treatment plans.

6. How do you know if you’re allergic to amoxicillin?

Amoxicillin is a penicillin antibiotic. So if you have a penicillin allergy you’ll likely be allergic to amoxicillin as well.

Good to know: “True” penicillin allergies aren’t very common. In fact, studies have found that in people who reported an allergic reaction to penicillins, over 90% didn’t have a “true” allergy. They were experiencing side effects of the antibiotic instead (more on this below). Also, people who experience an allergic reaction to penicillin as a child typically lose their allergy over time.

Symptoms of an amoxicillin allergy typically appear within 1 hour after taking a dose. These symptoms can include:

• Skin rash or hives (raised, itchy bumps)

• Swelling of the face

• Coughing or wheezing

• Tightness in the throat

• Difficulty breathing

• Fast heartbeat

• Nausea and vomiting

• Diarrhea

• Abdominal pain

• Confusion

• Dizziness

The most severe allergic reaction to amoxicillin is called anaphylaxis. Although rare, anaphylaxis can be life-threathening. If you develop a severe reaction after taking amoxicillin, call 911 or go to the nearest emergency room.

If you think you’re allergic to amoxicillin, talk to your healthcare professional. They can review your symptoms and may recommend allergy testing to confirm your allergy.

7. Is amoxicillin better than other antibiotics?

While amoxicillin is commonly used because of its effectiveness, affordability, and availability, that doesn’t mean it's better than other antibiotics. The best antibiotic depends on your infection, what’s causing it, and how serious it is.

Amoxicillin is a broad-spectrum antibiotic, meaning it works well against a wide range of bacteria. But it’s not always the right choice.

There are situations where other antibiotics may be preferred over amoxicillin. This is because other antibiotics, such as azithromycin (Zithromax, “Z-Pak”), target different types of bacteria than amoxicillin. Some are also administered in other ways, such as into a vein (IV). Amoxicillin is only available as an oral medication.

8. What are the most common side effects of amoxicillin?

Like with all medications, amoxicillin has different side effects. Common amoxicillin side effects include:

• Nausea and vomiting

• Diarrhea

• Skin rashes

• Taste and smell changes

• Headaches

Severe allergic reactions to amoxicillin are rare, but possible. Go to the emergency room or call 911 if you have trouble breathing or experience swelling of the face, lips, or tongue.

9. Is amoxicillin safe to take?

Yes, amoxicillin is considered safe to take. It’s generally tolerated well, too. But as mentioned above, it has a number of side effects to keep in mind. The good news is that most side effects are manageable and go away after you finish taking the antibiotic.

How to save on amoxicilli

There are ways to save on amoxicillin, which is available as both a brand-name and generic medication.

• Save with GoodRx. GoodRx can help you save over 60% off the average retail price of the generic version. Generic amoxicillin’s price at certain pharmacies is as low as $8.19 for 21 capsules of the 500 mg dose with a free GoodRx discount. You can find a 100 mL bottle of the 400 mg/5 mL oral suspension for as low as $11.16 with a free GoodRx discount.

• Save with Companion. You can access discounted prescription medications with a GoodRx Companion subscription. Over 250 medications are available for free, with hundreds more for under $10. The program also includes benefits to help you cut your self-pay costs, such as lower prices for online care visits, discounts on dental care, and other health services.

Why trust our experts?

Written by:

Sheila McAdoo, PharmD

Sheila McAdoo, PharmD, is a licensed pharmacist in Virginia and New York. She has worked in the pharmacy industry for 14 years.

Reviewed by:

Christina Aungst, PharmD, MWC

Christina Aungst, PharmD, MWC is a senior pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019.

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