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Azithromycin for Chlamydia: What to Do If You Vomit After Dosing

Azithromycin Single-Dose Therapy and Vomiting

Azithromycin 1 g orally (single dose) is a first-line regimen for uncomplicated urogenital chlamydia. Vomiting after dosing raises concern about absorption.

Guidance Based on Timing

Time After DoseAction
< 30 minutesLikely minimal absorption. Repeat full 1 g dose (with antiemetic if needed).
30–60 minutesPartial absorption uncertain. Repeat dose recommended by most experts (CDC, BASHH).
1–2 hoursSignificant absorption likely (Tmax ~2–3 h). Repeat dose may be considered; consult provider.
> 2 hoursAdequate absorption expected. No repeat needed.

Key Pharmacokinetics

  • Azithromycin has prolonged tissue half-life (~68 h) and high intracellular concentration.
  • Bioavailability ~37% (food reduces peak but not AUC).
  • Single dose achieves curative concentrations in genital mucosa for 7–10 days.

Practical Steps

  1. If vomiting occurs within 1–2 hours: Contact prescribing clinic/pharmacist same day.
  2. Request antiemetic (ondansetron 4–8 mg ODT) with repeat dose.
  3. Take with light food if nausea-prone (does not compromise efficacy).
  4. Do not split dose (e.g., 500 mg twice daily) for chlamydia—single dose is evidence-based.

Alternative Regimens (If Repeated Vomiting or Intolerance)

  • Doxycycline 100 mg PO BID × 7 days: Equal efficacy; requires adherence. Take with food, avoid lying down 30 min.
  • Other: Levofloxacin 500 mg × 7 days (if allergies/contraindications).

Follow-Up

  • Test-of-cure (NAAT) at 3–4 weeks post-treatment (earlier risks false positive from dead organisms).
  • Retest at 3 months (high reinfection rate).
  • Partner notification and treatment essential (EPT where legal).
  • Abstain until both partners treated and 7 days post-dose.

Vomiting shortly after azithromycin is common. Prompt repeat dosing ensures cure. Always complete partner management.

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