Amoxicillin

What Does Amoxicillin Do?

Amoxicillin, an antibiotic falling under the penicillin class, eradicates bacteria by destroying their cell walls. This disrupts the synthesis of bacterial cell walls leading to the bacterial death. It's effectively used for various bacterial infections including respiratory, ear, skin infections, urinary tract infections, and oral infections. It also has off-label uses in treating Lyme disease, Helicobacter pylori infections, and chlamydia.

Amoxicillin is the most widely-taken antibiotic in the World.

How Does Amoxicillin Work? (the complicated stuff)

Amoxicillin binds to penicillin-binding proteins (PBPs) and inhibits the transpeptidase enzyme needed for bacterial cell wall synthesis, preventing peptidoglycan cross-linking. This weakens the bacterial cell wall, causing it to become unstable and unable to withstand osmotic pressure, ultimately leading to cell lysis (bursting) and bacterial death. Amoxicillin is bactericidal, meaning it kills bacteria rather than merely inhibiting their growth, and it is most effective against actively dividing bacteria. It targets many Gram-positive bacteria, such as Streptococcus pneumoniae, and some Gram-negative bacteria, like Escherichia coli, making it highly effective for a wide range of bacterial infections. However, some bacteria produce beta-lactamase enzymes that break down amoxicillin, rendering it ineffective; therefore, it is often combined with clavulanic acid (e.g., Augmentin) to inhibit these enzymes and extend its spectrum of activity.

Put simply:

Amoxicillin works by stopping bacteria from building their protective outer wall, which is essential for their survival. It does this by blocking certain proteins and enzymes that bacteria use to create and strengthen their cell wall. Without a strong wall, bacteria become weak, burst open, and die. This makes amoxicillin very effective at killing bacteria, especially ones that are actively growing. It works well against many types of bacteria, including common ones that cause ear infections, throat infections, and some urinary and respiratory infections. However, some bacteria can produce enzymes that destroy amoxicillin, making it ineffective. To solve this problem, amoxicillin is sometimes combined with clavulanic acid (like in Augmentin), which helps stop those enzymes and allows the antibiotic to work better.

Drug Type and Category of Amoxicillin

Amoxicillin is a bacteriolytic antibiotic, meaning it works by killing bacteria through the destruction of their cell walls, causing the bacterial cells to burst (lyse). It falls under the penicillin class of antibiotics, a group of drugs derived from Penicillium mold. More specifically, amoxicillin is a beta-lactam antibiotic, named for its beta-lactam ring structure, which is essential for its antibacterial activity. 

Amoxicillin is classified as a broad-spectrum antibiotic, meaning it is effective against a wide range of bacterial infections.

What dosage of Amoxicillin should you be taking?

NHS Recommendations ¹

The NHS-recommended dosage of amoxicillin varies depending on factors such as the type and severity of the infection, the patient's age, and weight. Below are the general guidelines for common uses of amoxicillin:

Adults and Children Over 12 Years

Mild to Moderate Infections:  

   - 500 mg every 8 hours (three times a day).  

Severe Infections:  

   - 750 mg to 1 g every 8 hours.

Children Under 12 Years

The dosage for children is based on body weight and the severity of the infection. It is often given as a liquid suspension.  

- Standard Dose: 40–90 mg per kilogram of body weight per day, divided into 2 or 3 doses.  

For example:  

   - A child weighing 20 kg may be prescribed 250 mg every 8 hours.  

Specific Infections

1. Ear, Nose, and Throat Infections (e.g., tonsillitis):  

   - Adults: 500 mg every 8 hours.  

   - Children: Dose based on weight.  

2. Chest Infections (e.g., bronchitis or mild pneumonia):  

   - Adults: 500 mg every 8 hours.  

3. Urinary Tract Infections (UTIs):  

   - Adults: 500 mg every 8 hours.  

4. Dental Infections:  

   - Adults: 500 mg every 8 hours for 5 days.  

5. Helicobacter pylori Infections (as part of combination therapy for stomach ulcers):  

   - Adults: 750 mg to 1 g twice a day with other medications.

6. Severe or Recurrent Infections:  

   - Adults: Up to 1g every 8 hours.

Importantly:  

- Always take amoxicillin exactly as prescribed by a doctor.  

- Space doses evenly throughout the day (e.g., every 8 hours for three times daily dosing).  

- For liquid suspension, measure the dose carefully using the syringe or spoon provided.  

- Complete the full course of antibiotics, even if you start feeling better. Stopping early may allow the infection to return or bacteria to become resistant.

If you miss a dose, take it as soon as you remember, but do not double up to make up for a missed dose. Always consult your doctor or pharmacist for advice specific to your situation.

What are the side-effects of Amoxicillin?

The side effects of amoxicillin can range from mild to more severe, though not everyone will experience them. 

Common side effects include nausea, vomiting, diarrhea, skin rash, abdominal pain, headache, and loss of appetite. Uncommon side effects may include dizziness, itching, and fatigue.

Serious side effects require immediate medical attention and can include allergic reactions such as swelling of the face, lips, tongue, or throat, difficulty breathing, severe rashes, or hives. Rare but severe skin reactions like Stevens-Johnson syndrome (painful rash, peeling skin, and flu-like symptoms) or toxic epidermal necrolysis (widespread blistering and peeling skin) can occur. Persistent watery diarrhea during or after treatment may indicate Clostridium difficile-associated diarrhea. Liver problems, such as yellowing of the skin or eyes (jaundice), dark urine, or pale stools, can also occur. Seizures are rare but may happen, particularly at high doses or in people with kidney issues. Unexplained bruising or bleeding could signal blood disorders.

Other possible side effects include oral or vaginal thrush, as amoxicillin can disrupt the natural balance of bacteria, and, rarely, tooth discoloration, which is usually reversible with brushing.

If you experience mild side effects, they often resolve on their own, but contact your doctor if they persist. For serious side effects, stop taking amoxicillin and seek immediate medical attention. Report any concerns to your doctor, pharmacist, or local medicines regulatory authority, such as the Yellow Card Scheme in the UK.

Interactions

Amoxicillin can interact with other medications, supplements, and medical conditions, which may affect how it works or increase the risk of side effects. 

1. Other Medications:

- Methotrexate: Amoxicillin can reduce the elimination of methotrexate, leading to toxic levels in the body. This can cause serious side effects such as bone marrow suppression or kidney damage.

- Allopurinol: Taking allopurinol with amoxicillin increases the risk of skin rashes.

- Oral Contraceptives: Amoxicillin may reduce the effectiveness of hormonal birth control pills. Additional contraception (e.g., condoms) is recommended while taking amoxicillin.

- Anticoagulants (e.g., Warfarin): Amoxicillin can increase the risk of bleeding by enhancing the effect of warfarin. Monitoring of blood clotting time (INR) may be necessary.

- Probenecid: Probenecid slows the elimination of amoxicillin from the body, leading to higher levels of the antibiotic and potentially increasing its effects or side effects.

- Other Antibiotics: Combining amoxicillin with bacteriostatic antibiotics (e.g., tetracyclines or macrolides) may reduce its effectiveness since amoxicillin works best against actively growing bacteria.

2. Medical Conditions:

- Kidney Disease: Reduced kidney function can slow the removal of amoxicillin from the body, leading to higher drug levels and an increased risk of side effects. Dosage adjustments are often necessary.

- Mononucleosis (Glandular Fever): People with mononucleosis who take amoxicillin are at a higher risk of developing a widespread skin rash.

- Seizure Disorders: High doses of amoxicillin may increase the risk of seizures, especially in patients with pre-existing seizure conditions or kidney problems.

3. Vaccines:

- Live Typhoid Vaccine: Amoxicillin can reduce the effectiveness of the live oral typhoid vaccine. It is recommended to avoid taking the vaccine during or shortly after amoxicillin treatment.

4. Laboratory Tests:

- Amoxicillin can interfere with certain urine tests, such as glucose tests, leading to false-positive results. Inform your doctor if you are undergoing lab tests while on amoxicillin.

Natural Alternatives to Amoxicillin

There are several natural alternatives that may have antimicrobial properties similar to amoxicillin, but it's important to note that they are generally not a direct substitute for prescribed antibiotics, especially in the case of serious bacterial infections. Always consult a healthcare provider before using natural alternatives, particularly if the infection is severe or persistent. 

1. Garlic (Allium sativum) ²

Garlic has been widely studied for its antimicrobial properties. It contains a compound called allicin, which has shown antibacterial effects against a variety of pathogens, including Staphylococcus aureus, E. coli, and Salmonella. Studies suggest that garlic can be effective in fighting infections and may help boost the immune system.

2. Echinacea (Echinacea purpurea) ³

Echinacea is a popular herbal remedy that has immune-boosting and antibacterial properties. While it is more commonly used to prevent or treat colds and respiratory infections, some studies suggest it can have broad-spectrum antimicrobial effects against bacteria and viruses.

3. Manuka Honey ⁴

Manuka honey, particularly from New Zealand, has demonstrated antibacterial effects, primarily due to its high concentration of methylglyoxal. It is often used topically for wound infections and has been shown to fight bacteria like MRSA and E. coli. Some studies suggest that it may also have internal uses for fighting infections, though its effectiveness as an internal antibiotic is still under research.

4. Ginger (Zingiber officinale) ⁵

Ginger is well known for its anti-inflammatory and antimicrobial properties. Some research suggests that ginger can help inhibit bacterial growth and has a broad spectrum of antimicrobial action. It has been shown to be effective against several pathogens, including Streptococcus and Staphylococcus.

5. Coconut Oil ⁶

Coconut oil contains lauric acid, which has been shown to have antimicrobial and antiviral properties. It can be effective against certain bacteria, fungi, and viruses, including Staphylococcus aureus and Candida albicans. Though more commonly used topically, some studies suggest it may have benefits for internal use as well.

6. Turmeric (Curcuma longa) ⁷

Turmeric contains curcumin, a compound with well-documented anti-inflammatory and antimicrobial properties. It has been shown to be effective against various bacteria, including Streptococcus mutans and Salmonella typhi. It is often used in combination with black pepper to enhance absorption.

7. Goldenseal (Hydrastis canadensis) ⁸

Goldenseal is an herb that contains berberine, a compound known for its antibacterial, antifungal, and antiviral properties. It has been traditionally used to treat a variety of infections, including respiratory and gastrointestinal issues. Some research suggests that berberine can help fight bacterial infections, including E. coli and Staphylococcus aureus.

Interesting facts about Amoxicillin

Amoxicillin is effective only against bacterial infections, not viral infections. It is commonly misunderstood that it can treat colds, the flu, or other viral diseases, but it has no effect on viruses.

Amoxicillin has a relatively short half-life, meaning it is eliminated from the body fairly quickly. For most infections, amoxicillin is taken multiple times a day (typically every 8 hours), but the exact dosage depends on the type of infection being treated.

One reason amoxicillin is preferred for children is that the liquid suspension typically has a more palatable taste compared to other antibiotics, making it easier for children to take.

Unlike some antibiotics, amoxicillin is not typically associated with liver damage or dysfunction in healthy individuals. However, it may affect liver function in rare cases or in people with pre-existing liver conditions.

Disclaimer

This article is generated for informational purposes only. It was created in December 2024. Medications and medical guidance can change over time. Therefore, it is essential to consult with your general practitioner or healthcare provider before making any decisions regarding medications or treatment plans. Your GP can provide personalised advice based on your specific health needs and conditions.

References

1. https://www.nhs.uk/medicines/amoxicillin/
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4. Irish J, Carter D, Shapiro L, et al. The antibacterial activity of honey derived from Australian flora. *Int J Antimicrob Agents. 2006.
5. Tajuddin S, Brijesh T. Antibacterial activity of ginger extract against clinically isolated bacterial strains. Asian Journal of Plant Science & Research. 2013.
6. Ogbolu DO, Odu NN, Elegbede JA. Antimicrobial activity of coconut oil on Candida species in vitro. Journal of Medicinal Food. 2007.
7. Singh S, Aggarwal BB. Activation of transcription factor NF-kappa B is suppressed by curcumin (diferuloylmethane). J Biol Chem. 1995.
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