Standard Dosing for Amoxicillin in Sinus Infections
Adults typically take amoxicillin three times a day (every 8 hours) for acute bacterial sinusitis, with a common dose of 500 mg per tablet. Treatment usually lasts 5-10 days, depending on severity and response.[1][2]
Children are dosed by weight: 45-90 mg/kg/day divided into two or three doses (every 12 or 8 hours).[1][3]
Factors That Affect Dosing Frequency
- High-dose regimens: For resistant infections, 875 mg twice a day (every 12 hours) is sometimes used instead.[2][4]
- Age and weight: Kids under 3 months or with kidney issues may need adjusted schedules.[3]
- Form: Suspension for kids is often twice daily; tablets for adults lean toward three times.[1]
Always follow your prescription—do not self-adjust.
Why Three Times a Day Is Common
Amoxicillin has a short half-life (about 1-1.5 hours), so spacing doses maintains steady blood levels to fight bacteria like Streptococcus pneumoniae in sinuses.[4][5] Twice-daily options like amoxicillin-clavulanate (Augmentin) improve adherence but aren't plain amoxicillin.[2]
What If I Miss a Dose or Take Too Many?
Take the missed dose as soon as possible unless it's near the next one—then skip it. Overdose risks nausea, vomiting, or diarrhea; seek emergency care if severe.[1][6] Space doses evenly around the clock, even overnight.
Common Side Effects and When to Contact a Doctor
Diarrhea (most frequent), nausea, rash. Stop and call your doctor for allergic reactions (hives, swelling, breathing issues) or worsening sinus symptoms after 3 days.[1][2][5] Probiotics can help gut issues from antibiotics.
Alternatives If Amoxicillin Isn't Right