Amoxicillin: Uses, Side Effects, and Precautions

Generic name: amoxicillin

Brand names: Amoxil, Moxatag, Trimox, and Larotid

Drug class: penicillins

What is Amoxicillin and How Is It Used?

Amoxicillin is an antibiotic medication classified in the penicillin drug class. Other members of this class include ampicillin (Unasyn), piperacillin (Pipracil), and ticarcillin (Ticar), among others.

These antibiotics share a common mechanism of action: they don’t directly kill bacteria but rather inhibit their multiplication by preventing the formation of bacterial cell walls, which are crucial for their survival.

Amoxicillin is effective against a wide range of bacteria, including H. influenzae, N. gonorrhoea, E. coli, Pneumococci, Streptococci, and certain strains of Staphylococci. It was approved by the FDA in December 1974.

Common Uses of Amoxicillin

Amoxicillin is prescribed to treat infections caused by bacteria susceptible to its effects. Some common bacterial infections treated with amoxicillin include middle ear infections, tonsillitis, laryngitis, bronchitis, pneumonia, skin infections, gonorrhea, urinary tract infections, and Helicobacter pylori (H. pylori) infections. It is also used for anthrax, endocarditis, and as a treatment for gonorrhea.


  • Amoxicillin may cause hypersensitivity in individuals allergic to penicillins, cephalosporins, or imipenem.
  • Individuals with infectious mononucleosis (“mono”) should avoid amoxicillin due to the risk of developing a red skin rash.
  • Keep amoxicillin out of reach of children, and in case of overdose, seek medical assistance or contact a Poison Control Center immediately.

Side Effects of Amoxicillin

Common side effects associated with amoxicillin include diarrhea, dizziness, heartburn, insomnia, nausea, itching, vomiting, confusion, abdominal pain, easy bruising, bleeding, rash, and allergic reactions. It’s worth noting that those allergic to cephalosporin antibiotics may or may not be allergic to penicillins.

Serious but rare reactions to amoxicillin include seizures, severe allergic reactions (anaphylaxis), and low platelet (thrombocytopenia) or red blood cell count. Additionally, amoxicillin can disrupt the natural bacteria balance in the colon, potentially leading to conditions like pseudomembranous colitis. If you experience symptoms such as diarrhea, fever, abdominal pain, or shock after starting amoxicillin, contact your physician immediately.

Dosage Information

The recommended dosage for amoxicillin depends on the type and severity of the infection. For most infections in adults, the dose ranges from 250 mg every 8 hours to 875 mg every 12 hours. For the treatment of gonorrhea in adults, a single dose of 3 g is recommended.

In children older than 3 months but weighing less than 40 kg, dosages range from 25 to 45 mg/kg/day in divided doses every 12 hours or 20 to 40 mg/kg/day with one-third of the daily dose administered every 8 hours. Amoxicillin can be taken with or without food.


Amoxicillin is rarely associated with significant drug interactions. It has moderate interactions with around 27 different drugs, while mild interactions include drugs like amiloride, azithromycin, and pyridoxine (antidote).

Always inform your healthcare provider about all medications you are taking to assess potential interactions correctly.

Pregnancy and Breastfeeding

Penicillins, including amoxicillin, are generally considered safe for pregnant women who are not allergic to penicillin. Small amounts of amoxicillin can be excreted in breast milk, potentially causing diarrhea or allergic reactions in nursing infants. However, amoxicillin is still considered safe for use while breastfeeding and is commonly used to treat infections in newborns.

Additional Information

Amoxicillin is available in various forms, including capsules (250 and 500 mg), tablets (500 and 875 mg), chewable tablets (125, 200, 250, and 400 mg), and powder for suspension (50 mg/ml; 125, 200, 250, and 400 mg/5 ml). Extended-release tablets are also available in 775 mg.

Storage conditions for amoxicillin vary depending on the form, but generally, it should be stored at or below specific temperature thresholds to maintain its effectiveness.

In summary, amoxicillin is a widely used antibiotic with a broad spectrum of applications, but it should be taken under medical supervision, considering potential side effects and interactions. Pregnant or breastfeeding individuals should consult their healthcare providers before using amoxicillin.

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