Quick Answer

The STI antibiotic map: azithromycin or doxycycline for chlamydia; ceftriaxone injection for gonorrhea; benzathine penicillin for syphilis; metronidazole or tinidazole for trichomoniasis and bacterial vaginosis — with moxifloxacin reserved for resistant mycoplasma genitalium.

  • Doxycycline 100mg twice daily × 7 days: current first-line chlamydia monotherapy.
  • Ceftriaxone 500mg IM single dose: gonorrhea's last reliable first-line agent as resistance climbs.
  • Penicillin G benzathine IM: syphilis gold standard — one dose early stages, three weekly for late.
  • Metronidazole 2g single dose: trichomoniasis and BV share this therapy.
  • Amoxicillin does NOT treat standard STIs reliably — a persistent myth from dental-prescribing confusion.

The Landscape

Each antibiotic targets specific organism vulnerabilities: cell-wall synthesis (penicillins/cephalosporins), protein assembly (doxycycline), DNA processes (metronidazole's radical mechanism). Matching drug-to-bug determines success — broad-spectrum guessing loses to targeted precision.

Resistance watch

Gonococcus developed resistance to every prior first-line agent sequentially — penicillin, then fluoroquinolones, then azithromycin. Ceftriaxone remains effective but surveillance continues; resistance-aware prescribing isn't optional.

Allergy accommodations

Penicillin-allergic syphilis patients receive doxycycline alternatives with enhanced follow-up; true anaphylactic histories deserve allergist consultation since 90% of 'penicillin allergies' test negative.

Treatment Windows by Infection

Bacterial infections clear with antibiotics measured in days: a single 500 mg intramuscular ceftriaxone dose for gonorrhea (doxycycline is added only if chlamydia has not been ruled out), seven days of doxycycline for chlamydia, penicillin injections for syphilis staged by duration. Viral infections play a longer game — suppressive antivirals for herpes, daily ART driving HIV to undetectable, and 8–12-week antiviral courses curing over 95% of hepatitis C cases.

Frequently Asked Questions

What is metronidazole used for treating std?

The STI antibiotic map: azithromycin or doxycycline for chlamydia; ceftriaxone injection for gonorrhea; benzathine penicillin for syphilis; metronidazole or tinidazole for trichomoniasis and bacterial vaginosis — with moxifloxacin reserved for resistant mycoplasma genitalium.

Can penicillin treat std?

The STI antibiotic map: azithromycin or doxycycline for chlamydia; ceftriaxone injection for gonorrhea; benzathine penicillin for syphilis; metronidazole or tinidazole for trichomoniasis and bacterial vaginosis — with moxifloxacin reserved for resistant mycoplasma genitalium.

Can doxycycline treat std?

The STI antibiotic map: azithromycin or doxycycline for chlamydia; ceftriaxone injection for gonorrhea; benzathine penicillin for syphilis; metronidazole or tinidazole for trichomoniasis and bacterial vaginosis — with moxifloxacin reserved for resistant mycoplasma genitalium.

Will doxycycline treat std?

The STI antibiotic map: azithromycin or doxycycline for chlamydia; ceftriaxone injection for gonorrhea; benzathine penicillin for syphilis; metronidazole or tinidazole for trichomoniasis and bacterial vaginosis — with moxifloxacin reserved for resistant mycoplasma genitalium.

Can penicillin cure std?

The STI antibiotic map: azithromycin or doxycycline for chlamydia; ceftriaxone injection for gonorrhea; benzathine penicillin for syphilis; metronidazole or tinidazole for trichomoniasis and bacterial vaginosis — with moxifloxacin reserved for resistant mycoplasma genitalium.

How to take azithromycin for std?

The STI antibiotic map: azithromycin or doxycycline for chlamydia; ceftriaxone injection for gonorrhea; benzathine penicillin for syphilis; metronidazole or tinidazole for trichomoniasis and bacterial vaginosis — with moxifloxacin reserved for resistant mycoplasma genitalium.

Related Questions

⚕️ This page is educational and does not replace advice from a licensed clinician. If you may have been exposed to an STI, get tested — most infections are manageable, and many are fully curable.

Sources & Further Reading

Figures reflect CDC surveillance and WHO estimates; they are population statistics, not personal risk predictions.