The best antibiotic for chlamydia is doxycycline, taken twice daily for seven days. The best antibiotic for gonorrhea is ceftriaxone, given as a single injection. These two infections are frequently diagnosed together, and when they are, both antibiotics are used at the same time.
Why These Two Infections Are Often Treated Together
Chlamydia and gonorrhea overlap more than most people realize. Among women diagnosed with gonorrhea, anywhere from 18% to 58% also test positive for chlamydia. Because both infections can be present without symptoms, the CDC recommends treating for chlamydia whenever gonorrhea is diagnosed and chlamydia hasn’t been ruled out. In practice, this means many people receive treatment for both at once: an injection for gonorrhea plus a week of pills for chlamydia.
Chlamydia: Doxycycline for Seven Days
Doxycycline 100 mg taken by mouth twice a day for seven days is the CDC’s recommended first-line treatment for chlamydia in adolescents and adults. It replaced azithromycin (a single-dose pill) as the preferred option because it consistently produces higher cure rates. Azithromycin is still listed as an alternative, but it’s no longer the top choice for most people.
The exception is pregnancy. Doxycycline isn’t safe during pregnancy, so azithromycin remains the recommended treatment for pregnant individuals. Amoxicillin taken three times daily for seven days is a backup option during pregnancy as well.
Doxycycline can cause stomach upset and sun sensitivity, so taking it with food and avoiding prolonged sun exposure during the week of treatment helps. You’ll need to finish all seven days even if symptoms clear up sooner.
Gonorrhea: A Single Ceftriaxone Injection
Gonorrhea is treated with a single 500 mg intramuscular injection of ceftriaxone. For people weighing 300 pounds (150 kg) or more, the dose is increased to 1,000 mg. This applies to gonorrhea infections of the genitals, rectum, or throat. The injection is given in a clinic or doctor’s office, typically in the hip or upper arm, and takes just a few seconds.
There is no recommended oral pill for gonorrhea as a first choice. Gonorrhea has developed resistance to nearly every class of antibiotic used against it over the decades, including older options like ciprofloxacin (which now shows resistance rates up to 100% in some countries). Ceftriaxone remains effective, but global surveillance shows resistance to this drug class is creeping upward too, which is why getting the full recommended dose matters.
If You Have a Cephalosporin Allergy
Ceftriaxone belongs to the cephalosporin family of antibiotics. If you’re allergic to cephalosporins, the alternative for gonorrhea is a combination of two drugs: a single injection of gentamicin (240 mg) plus a single oral dose of azithromycin (2 g, which is a higher dose than used for chlamydia alone). If ceftriaxone simply isn’t available, an oral cephalosporin called cefixime at 800 mg can substitute, though it’s considered less reliable, especially for throat infections.
What Treatment Looks Like in Practice
If you’re being treated for both infections, a typical visit involves getting the ceftriaxone injection at the clinic and leaving with a prescription for a week of doxycycline. The gonorrhea side is handled in one visit. The chlamydia side requires you to complete the full course of pills at home.
You should avoid sexual contact for seven days after treatment begins, or until both you and your partner have completed treatment. Reinfection is common, especially if a partner goes untreated. Some states allow what’s called expedited partner therapy, where your doctor can prescribe medication for your partner without seeing them in person. Ask your provider whether this is an option where you live.
Retesting After Treatment
The CDC recommends retesting three months after treatment for both chlamydia and gonorrhea. This isn’t a test of whether the antibiotics worked (they almost always do when taken correctly). It’s a screen for reinfection, which happens frequently when sexual partners aren’t treated at the same time. If three months have passed and you haven’t been retested, it’s worth scheduling that follow-up, even if you feel fine. Both infections can persist without symptoms while still causing damage to reproductive organs over time.