Can a patient use amoxicillin?

Can a Patient Use Amoxicillin?

Yes, amoxicillin can be used by most patients for appropriate bacterial infections, but it is absolutely contraindicated in patients with a history of serious hypersensitivity reactions (anaphylaxis or Stevens-Johnson syndrome) to amoxicillin or other beta-lactams. 1

Absolute Contraindications

• History of serious hypersensitivity reactions including anaphylaxis or Stevens-Johnson syndrome to amoxicillin or other beta-lactams (penicillins or cephalosporins) 1
• Patients who are hypersensitive to penicillins should not receive amoxicillin 2

Key Safety Considerations Before Prescribing

Allergy Assessment

• Differentiate Type I immediate hypersensitivity (anaphylaxis, angioedema, urticaria) from non-serious reactions like mild rash 2
• Patients with non-Type I reactions (e.g., simple rash) may tolerate cephalosporins as alternatives 2
• For true Type I hypersensitivity to beta-lactams, use macrolides, fluoroquinolones, or TMP/SMX instead, though these have limited effectiveness against major pathogens 2

Clinical Indications Where Amoxicillin Is Appropriate

Upper and Lower Respiratory Tract Infections:

• Acute bacterial rhinosinusitis in adults and children 2
• Community-acquired pneumonia (often combined with macrolide) 2
• Acute otitis media 3
• Bacterial exacerbations of chronic bronchitis 4

Other Infections:

• Genitourinary tract infections 1
• Skin and skin structure infections 1
• Helicobacter pylori infection (in combination therapy) 1

Dosing Considerations

Adults: 750-1750 mg/day divided every 8-12 hours 1

Pediatric patients >3 months: 20-45 mg/kg/day divided every 8-12 hours 1

High-dose regimens (90 mg/kg/day in children, 4 g/day in adults) are recommended when:

• Recent antibiotic use within 4-6 weeks 2
• High prevalence of drug-resistant Streptococcus pneumoniae in the area 2
• Moderate to severe disease 2

Renal impairment: Reduce dose when GFR <30 mL/min 1

Important Warnings

Monitor for Severe Reactions

• Anaphylactic reactions: Serious and occasionally fatal reactions have occurred; discontinue immediately if reaction develops 1
• Severe cutaneous adverse reactions (SCAR): Monitor closely and discontinue if rash progresses 1
• Clostridioides difficile-associated diarrhea: Evaluate if diarrhea occurs during or after treatment 1

Drug Interactions to Avoid or Monitor

• Probenecid: Coadministration not recommended 1
• Oral anticoagulants: May increase prothrombin time prolongation; monitor INR 1
• Allopurinol: Increases risk of rash 1
• Oral contraceptives: May reduce efficacy; advise backup contraception 1

Common Pitfalls

• Do not use amoxicillin monotherapy for hospitalized community-acquired pneumonia; combine with a macrolide to cover atypical pathogens 2
• Avoid in patients with recent antibiotic exposure without using high-dose formulations or combination therapy, as resistance is more likely 2
• Do not dismiss mild rash as allergy without proper assessment; many patients with non-serious reactions can tolerate beta-lactams 2
• The most common adverse reactions (>1%) are diarrhea, rash, vomiting, and nausea 1