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Amoxicillin (Amoxil): overview, uses and side effects

Dr Karen Martin
Reviewed by Dr Karen MartinReviewed on 19.10.2023 | 11 minutes read

Amoxicillin is a type of antibiotic from the penicillin family. It is used in adults, children and infants to treat a range of different bacterial infections such as chest infections, sinusitis, tonsillitis, dental abscesses, ear infections and Lyme disease. It can come in capsules, oral suspension, chewable, and injection formulations. Amoxicillin is only available on prescription. Amoxil is a branded version of amoxicillin.

Doctor’s advice

How do I take it?

Your doctor will prescribe a specific amoxicillin dose, adapted for children and the condition being treated. Make sure you space the doses evenly throughout the day, and it is important that you finish the full course of treatment prescribed by your doctor, even if your symptoms have gone away.

Your pharmacist will make oral suspensions, and most of these formulations should be stored in the fridge. Shaking the bottle well before use to evenly disperse the medicine is essential. For oral powder sachets, add 10 to 20 ml water to the powder, shake until a suspension is formed, and drink it immediately.

Amoxicillin can interfere with certain urine and blood tests, so if you are getting any tests done, make sure the healthcare professional carrying out the test is aware you are taking amoxicillin.

What to do if you miss a dose

Let's delve deeper into the considerations when deciding whether to take a missed dose or continue with the regular schedule of amoxicillin. Understanding the medication can help with making this decision. However, if you are ever unsure, always speak to a professional. We here at Healthwords want to empower our users to make informed decisions.

Taking a missed dose

If you miss a dose but remember well before the next scheduled dose, taking the missed dose promptly is generally advised. This helps maintain consistent levels of amoxicillin in the bloodstream to combat the bacterial infection effectively.

However, it is essential to note when you take this dose, as you will have to reschedule all future doses. For example, if you take your doses at 8 AM, 2 PM & 8 PM, miss the middle dose, then realize at 3 PM you haven't had your dose and want to take it then, we recommend shifting your new dosing timings to one hour later, which is 9 AM, 3 PM & 9 PM.

Half-life explained: Amoxicillin has a relatively short half-life, which means it stays in the body for a limited time before being eliminated. The half-life of amoxicillin is around one to two hours. Taking the missed dose promptly helps compensate for the decreasing drug concentration in the body.

Therapeutic window explained: The therapeutic window represents the range of drug concentrations in the body where the medication is effective but does not cause harmful side effects. Consistency in dosing helps keep amoxicillin within its therapeutic window, ensuring optimal efficacy.

Continuing regular schedule

If the time for the next scheduled dose is approaching and you remember a missed dose, it may be prudent to skip it. This prevents the risk of double dosing, as taking doses too close together can lead to an elevated concentration of the drug. Your schedule will continue as normal. For example, if you take your doses at 8 AM, 2 PM & 8 PM, you miss the middle dose, you then realize at 7 PM you haven't had your dose, we recommend waiting till 8 PM and continuing taking as you would have.

While amoxicillin is generally well-tolerated, taking too much within a short time frame can increase the likelihood of side effects. The side effect window refers to the period when side effects are more likely to occur. Adhering to the prescribed schedule helps minimize side effects.

Skipping the missed dose and sticking to the regular schedule helps avoid potential complications related to excessive drug concentration, ensuring the medication's safety and effectiveness.

Important Considerations

  • Maintaining a consistent dosing schedule is crucial for the antibiotic to combat the infection effectively.

  • Always consult your healthcare provider or pharmacist for guidance, especially if you have concerns or if missing doses become a recurrent issue.

In summary, deciding to take a missed dose or continue with the regular schedule depends on the time elapsed since the missed dose, the proximity to the next scheduled dose, and individual factors. Consulting with your local healthcare professional ensures a tailored approach based on your specific circumstances and medical history.

How does amoxicillin work?

Bacteria have a protective outer layer called the cell wall, which maintains the structure and integrity. This cell wall is essential for bacteria to survive and replicate. Below is a simplified explanation of how amoxicillin affects the cell wall:

  • Binds to Penicillin Binding Proteins (PBPs) - this interferes with the synthesis of the bacterial cell wall because PBPs are crucial enzymes involved in the construction of the wall.

  • Inhibits the Transpeptidation Process- this is a key step in the formation of the bacterial cell wall. Transpeptidation involves the cross-linking of peptidoglycan chains, providing strength and stability to the cell wall.

  • Weakens the cell wall - by binding to PBPs and interfering with transpeptidation, amoxicillin weakens the bacterial cell wall. This disruption makes the bacterial cell more susceptible to the internal pressure generated during growth and replication.

  • Causes cell lysis - Without a properly formed and robust cell wall, the affected bacteria are unable to maintain their structural integrity. As a result, the internal pressure causes the bacterial cell to lyse (burst), leading to the death of the bacterium.

It's important to note that amoxicillin is effective against a wide range of bacteria but not against viruses. Therefore, it is specifically prescribed for bacterial infections. Additionally, the effectiveness of amoxicillin can be impacted by bacterial resistance, so healthcare professionals carefully consider the choice of antibiotics based on the type of bacteria causing the infection.

How does amoxicillin compare with other antibiotics?

Amoxicillin, a widely prescribed antibiotic, exhibits distinct characteristics in comparison to other antibiotics. This overview will explore its spectrum of activity, uses, safety profile, and side effects, providing insights into how amoxicillin stands out in antibiotic therapy. However, allergic reactions, including rash and rarely severe reactions like anaphylaxis, are possible. Consultation with healthcare providers is crucial for those with a history of penicillin allergy.

#1 Amoxicillin (Penicillin)

Belongs to the class of penicillin antibiotics and is considered broad-spectrum. It is effective against a wide range of bacteria, making it suitable for treating various bacterial infections. Unlike narrow-spectrum antibiotics that target specific types of bacteria, amoxicillin acts against a broader array, offering versatility in treating infections caused by different bacterial strains. It is generally well-tolerated.


  • respiratory infections - amoxicillin is commonly prescribed for respiratory tract infections such as bronchitis and pneumonia.

  • ear infections - effective in treating middle ear infections, especially in children.

#2 Azithromycin (Macrolide)

Broad-spectrum antibiotic, particularly effective against respiratory and skin infections. Generally well-tolerated, with side effects such as gastrointestinal upset and rare cardiac effects.


  • respiratory tract infections.

  • skin and soft tissue infections.

#3 Ciprofloxacin (Fluoroquinolone)

Broad-spectrum antibiotics, used for various bacterial infections. Associated with potential side effects like tendon rupture and central nervous system effects; reserved for specific infections due to safety concerns.


#4 Doxycycline (Tetracycline)

Broad-spectrum antibiotic, effective against a wide range of bacteria. It can cause gastrointestinal upset and photosensitivity. Not suitable in children under 10 due to reduction in bone density and growth.


  • respiratory infections.

  • acne.

#5 Co-amoxiclav (Broad Spectrum)

Broad-spectrum antibiotic combining amoxicillin and clavulanic acid. Similar to amoxicillin, clavulanic acid helps counteract bacterial resistance and makes the amoxicillin work a little better.


  • respiratory tract infections.

  • skin and soft tissue infections -post-human/dog bite.

#6 Trimethoprim-Sulfamethoxazole (Sulfonamide)

Broad-spectrum antibiotics are effective against various bacteria. May lead to skin reactions and, in rare cases, severe adverse effects like Stevens-Johnson syndrome.


  • urinary tract infections.

#7 Clarithromycin (Macrolide)

Broad-spectrum antibiotic, effective against respiratory and skin infections. Generally well-tolerated, with potential side effects similar to other macrolides.


  • respiratory tract infections.

  • Helicobacter pylori (H. pylori) eradication.

#8 Cefuroxime (Cephalosporin)

Broad-spectrum antibiotic with activity against various bacteria, often second or third-line treatment. Generally well-tolerated, those with severe penicillin allergy may also react to cefuroxime.


  • respiratory tract infections.

  • skin and soft tissue infections - not so commonly used.

  • severe eye infections.

#9 Erythromycin (Macrolide)

Broad-spectrum antibiotic, effective against respiratory and skin infections. Generally well-tolerated, with potential gastrointestinal side effects.


  • respiratory tract infections - amoxicillin allergic patient.

  • skin and soft tissue infections.

#10 Metronidazole (Nitroimidazole)

Effective against anaerobic bacteria and certain parasites. Generally well-tolerated; may cause gastrointestinal upset. Not safe to be taken with alcohol.


In conclusion, amoxicillin is a versatile and widely used antibiotic with a broad spectrum of activity. Compared to other antibiotics, its safety profile often positions it favorably in clinical practice, making it a common choice for various bacterial infections according to treatment guidelines. However, individual patient factors and the specific nature of the infection play a role in determining the most appropriate antibiotic therapy.

Who should not take amoxicillin?

Like all medications, don’t take them if you have previously had an allergic reaction to it, or if you have other medications or medical conditions where you would normally discuss with your doctor or pharmacist before starting something new as there may be an interaction between the medication and amoxicillin.

As amoxicillin is only available on prescription, your doctor will prescribe it for you if they feel it would be beneficial. Be sure to let your doctor know if you have had a reaction or allergy to any of the penicillin family of medications before.

Pregnancy and breastfeeding

Amoxicillin is generally considered safe to take during pregnancy. Extensive research and clinical experience suggest that the benefits of treating bacterial infections with amoxicillin often outweigh the potential risks. No apparent harm observed in animal studies and limited, well-controlled human studies showing no risk during pregnancy.

Amoxicillin is deemed safe for breastfeeding mothers. Only minimal amounts of the antibiotic enter breast milk, and at such levels, side effects in the baby are not anticipated. This makes amoxicillin a preferred choice when antibiotic therapy is necessary for nursing mothers.

Are there any side effects?

Like all medications, amoxicillin can induce side effects, although not everyone will experience them.

Common Side Effects (occur in around 1 in 10 people):

If these common side effects persist or bother you, it is advisable to consult your doctor or pharmacist.

Serious Side Effects (rare, occurring in less than 1 in 1,000 people):

Seek immediate medical attention by calling a doctor or 911 if you experience:

  • Diarrhea containing blood or mucus or severe diarrhea lasting more than 4 days.

  • Pale poop and dark pee, accompanied by yellowing of the eyes or skin, which may indicate liver or gallbladder problems.

  • Bruising or changes in skin color.

  • Joint or muscle pain emerging after 2 days of taking the medicine.

  • A skin rash with circular red patches.

Note: Some serious side effects may manifest up to 2 months after completing the amoxicillin course.

Serious Allergic Reaction (occurs in around 1 in 15 people):

Immediate action is required (call 911) if you experience severe symptoms such as swollen lips, difficulty breathing, tight throat, skin discoloration, confusion, or fainting.

Coping with Side Effects

Feeling Sick - Stick to simple meals, avoid rich or spicy food, and consider taking amoxicillin after a meal or snack. If you do throw up, it is worth speaking to your doctor or pharmacist to see if you need to take another dose

Diarrhea - Stay hydrated with water or electrolyte solutions. If severe, consult a pharmacist or doctor before taking any other medications. For individuals using contraception, prolonged severe diarrhea (over 24 hours) may affect contraceptive effectiveness.

For a comprehensive list of side effects, refer to the leaflet inside your medicine packet.

Understanding and promptly addressing side effects is crucial for ensuring the safe and effective use of amoxicillin. If you have concerns or persistent symptoms, consult your healthcare provider for guidance.

Is amoxicillin safe to take with other medicines?

When considering amoxicillin, it's essential to be aware of potential interactions with other medications, ensuring optimal safety and effectiveness. Here are key points to keep in mind:

Medication Interactions

  1. Methotrexate: Used for arthritis and psoriasis. Combining methotrexate with amoxicillin may enhance the risk of certain side effects. Your doctor should be informed if you are on methotrexate.

  2. Warfarin: A blood clot prevention medication. Concurrent use with amoxicillin may require dosage adjustments. Your doctor will monitor your blood clotting parameters closely.

  3. Gout medicines (probenecid or allopurinol): Combining with amoxicillin may affect the excretion of the antibiotic. Your doctor will consider appropriate dosages and monitor for any adverse effects.

  4. Combining amoxicillin with other antibiotics may not be necessary and can potentially increase the risk of side effects. Inform your doctor about any ongoing antibiotic treatments.

  5. Oral typhoid vaccine: If you have recently had or are scheduled for an oral typhoid vaccine, be sure to inform your doctor. Amoxicillin can reduce the effectiveness of this vaccine, and alternative vaccination strategies may be considered.

Herbal Remedies and Supplements Interactions

Limited information exists regarding interactions between amoxicillin and herbal remedies or supplements. It's advisable to discuss any herbal products or supplements you are taking with your healthcare provider to assess potential interactions.

  1. Always disclose your complete medication list, including over-the-counter drugs, supplements, and herbal remedies, to your healthcare provider before starting amoxicillin.

  2. Regular communication with your doctor is crucial to monitor for any signs of adverse reactions or changes in your health status.

  3. If you experience unexpected symptoms or side effects while taking amoxicillin alongside other medications, seek prompt medical advice.

While amoxicillin is generally well-tolerated, it's important to exercise caution and communicate openly with your healthcare provider regarding your medication regimen.

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Dr Karen Martin
Reviewed by Dr Karen Martin
Reviewed on 19.10.2023
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