Amoxicillin Dosing for Adults Weighing 180 Pounds
For an adult weighing 180 pounds (approximately 82 kg), the standard amoxicillin dose is 500 mg every 8 hours OR 875 mg every 12 hours for most infections, with higher doses of 875 mg every 8 hours or 500 mg every 8 hours for severe infections or lower respiratory tract infections 1.
Standard Dosing by Infection Severity
The FDA-approved dosing for adults depends on the infection site and severity 1:
Mild to Moderate Infections
- Ear/Nose/Throat, Skin, or Genitourinary infections: 500 mg every 12 hours OR 250 mg every 8 hours
- This translates to 1,000-1,500 mg total daily dose
Severe Infections or Lower Respiratory Tract Infections
- 875 mg every 12 hours (1,750 mg/day) OR 500 mg every 8 hours (1,500 mg/day)
- These higher doses are appropriate for pneumonia, severe sinusitis, or infections requiring more aggressive treatment 1
Important Administration Details
Take amoxicillin at the start of a meal to minimize gastrointestinal side effects 1. This is particularly important as GI intolerance is the most common adverse effect.
Duration of Therapy
Continue treatment for 48-72 hours beyond symptom resolution or evidence of bacterial eradication 1. For streptococcal infections (like strep throat), a minimum 10-day course is mandatory to prevent acute rheumatic fever 1.
Special Considerations for This Patient
At 180 pounds, this patient falls within normal adult weight range and does not require dose adjustment based on body weight alone. Recent evidence suggests that obesity-related dose adjustments are generally not needed for amoxicillin in non-critically ill patients 2.
When to Use Higher Doses
Consider the 875 mg every 12 hours regimen if:
- Treating lower respiratory tract infections (pneumonia, bronchitis)
- Severe infections with systemic symptoms
- Geographic areas with high penicillin-resistant Streptococcus pneumoniae prevalence
- Recent antibiotic use within 4-6 weeks 3, 4
Renal Function Caveat
Do NOT use the 875 mg dose if the patient has severe renal impairment (GFR <30 mL/min). In such cases, reduce to 500 mg or 250 mg every 12-24 hours depending on severity 1.
Common Pitfalls to Avoid
- Don't underdose respiratory infections: Lower respiratory tract infections require the higher dose regimen (875 mg every 12 hours or 500 mg every 8 hours), not the mild infection dose 1
- Don't exceed adult maximum: The total daily dose should not exceed 4 grams per day 1
- Don't forget meal timing: Taking amoxicillin with food significantly reduces GI side effects without compromising absorption 1