This page is general health information, not medical advice. It cannot tell you whether you have an infection. A clinician can, and the testing options on this site are a good place to start.

Doxy-PEP is a newer option in sexual health care. The name is short for doxycycline post-exposure prophylaxis. It means a clinician prescribes an antibiotic that a person takes after sex to lower the chance of certain bacterial infections.

You may see it written as doxypep or doxy pep. All three spellings mean the same thing. This guide explains what the CDC says about it, who the guidance covers, what it does and does not do, and which San Antonio organizations say they offer it.

What doxy-PEP is

Doxy-PEP uses doxycycline, an antibiotic that a clinician prescribes. It is a different approach from PrEP. PrEP is medicine that lowers the chance of getting HIV. Doxy-PEP is aimed at three bacterial infections: syphilis, chlamydia and gonorrhea.

The CDC published clinical guidance on doxy-PEP in 2024. It is part of the CDC's updates that build on the 2021 STI Treatment Guidelines.

Doxy-PEP is a prescription-only strategy. This article does not cover how much to take or how often. A clinician decides that after a conversation about your health, your history and your other medicines.

The science in plain terms

What the medicine is

Doxycycline belongs to the tetracycline class of antibiotics. Chemically, tetracyclines share a four-ring structure. They work by blocking bacteria from making the proteins they need to grow and multiply.

Because of that action, doxycycline is already used by clinicians for several bacterial infections. The CDC STI Treatment Guidelines (2021) name it as a treatment option for chlamydia, for example. Doxy-PEP applies the same medicine in a different way: as a short-term step after a possible exposure, instead of treatment for an infection that has already been found.

What the research suggests

Several clinical trials looked at doxy-PEP, mostly among gay and bisexual men and transgender women. The CDC reviewed this work for its 2024 guidance.

Research suggests that people who took doxycycline after condomless sex had fewer diagnoses of syphilis and chlamydia than people who did not. The effect on gonorrhea looked smaller. Researchers think this is partly because some gonorrhea bacteria are already resistant to tetracyclines.

One trial among cisgender women in Kenya did not show a clear benefit. Because of that, the CDC says the evidence is not strong enough to make a recommendation for cisgender women or for heterosexual men. That is a statement about evidence, not about who deserves care. More research is under way.

These are observations from studies, and results in everyday clinic use can differ.

Who the CDC 2024 guidance covers

The CDC recommends that clinicians discuss doxy-PEP with, and offer it to, a specific group:

Gay, bisexual and other men who have sex with men
Transgender women
People in either group who had a bacterial STI (syphilis, chlamydia or gonorrhea) in the past 12 months

For other people, the CDC says clinicians can use shared decision-making. That means you and your clinician talk through your situation together. Your clinician can tell you whether doxy-PEP fits your situation and what the evidence does and does not say for you.

You do not have to fit a category to ask. You can bring up doxy-PEP at any visit, whatever your gender or orientation.

The 72-hour window

The CDC's guidance describes doxy-PEP as a medicine taken after condomless oral, vaginal or anal sex. The CDC says it should be taken as soon as possible, and within 72 hours, after that sex. It is not meant to be taken before sex, and it is not a substitute for treatment if an infection is already present.

The 72-hour limit is a CDC detail worth knowing. Your clinician will explain the plan that applies to you, including how it fits with your other health needs.

What doxy-PEP does not do

Doxy-PEP has limits. According to the CDC, it:

Does not prevent HIV. PrEP, condoms and treatment as prevention are the tools for HIV.
Does not prevent viral infections such as herpes or HPV, or mpox.
Is not as strong against gonorrhea as it appears to be against syphilis and chlamydia, because of resistance.
Does not replace testing. The CDC advises that people who use doxy-PEP still have regular STI screening, because infections can still happen.

Think of it as one layer of protection. Condoms, vaccines such as HPV and hepatitis B, PrEP for HIV, and regular testing are other layers. They work together.

Safety profile and contraindications

Doxycycline has been used for decades, so clinicians know its common side effects well. The ones people most often notice include an upset stomach or nausea, and increased sensitivity to sunlight, which can make sunburn easier.

Rarer problems include irritation of the esophagus (the tube from the throat to the stomach). Clinicians usually ask people to take the medicine with a full glass of water and to stay upright afterward. Your clinician or pharmacist can walk through the specifics.

Some people should talk with a clinician carefully before using it:

People who are pregnant or may become pregnant. The tetracycline class is generally avoided in pregnancy, so this needs a clinician's guidance. Prenatal care includes its own syphilis screening, discussed below.
People with a past allergic reaction to tetracycline antibiotics.
People taking other medicines or supplements. Some products, such as those containing calcium, iron or magnesium, can affect how doxycycline is absorbed. Tell your clinician everything you take.

If you are on PrEP or live with HIV, doxy-PEP is a conversation to have with the clinician who manages that care.

Resistance concerns

Antibiotic resistance is the main public health question around doxy-PEP. When antibiotics are used more widely, bacteria can adapt. The CDC's guidance notes a few specific concerns:

Gonorrhea bacteria that resist tetracyclines are already common, which is why doxy-PEP works less well for gonorrhea.
Doxycycline use could contribute to resistance in other bacteria, such as Staphylococcus aureus, which can cause skin infections.
Wider use could push resistance in gonorrhea even higher over time.

This is why the CDC recommends doxy-PEP for a defined group, with monitoring, and not for everyone. Clinics that offer it are expected to keep testing people regularly. Public health researchers are watching resistance patterns closely.

Why this matters in San Antonio

The Texas Department of State Health Services (DSHS) STD Surveillance Report for 2022 gives local numbers. In Bexar County that year, DSHS reported 12,305 chlamydia cases and 5,983 gonorrhea cases. The gonorrhea rate was 290.5 per 100,000 people, compared with 207.0 per 100,000 for Texas as a whole that same year.

For primary and secondary syphilis, DSHS reported 500 Bexar County cases in 2022, a rate of 24.3 per 100,000. The Texas rate was 15.5. DSHS also reported 2,602 syphilis cases at all stages in Bexar County. DSHS notes these figures can change slightly as data are cleaned.

Those are the infections doxy-PEP is meant to reduce, which is why the topic comes up in San Antonio sexual health care. Numbers like these describe a community, not any one person. They are a reason to test regularly, whatever your health plan or background.

Where San Antonio organizations stand

Availability changes, so confirm with the organization before you go. Here is what is published today.

San Antonio AIDS Foundation (SAAF)

The San Antonio AIDS Foundation says on its website that it offers PrEP and Doxy PEP. SAAF is at 818 E. Grayson Street, San Antonio, TX 78208, and its phone number is (210) 225-4715.

Its testing page lists rapid HIV, syphilis, gonorrhea and chlamydia testing at no cost, with no appointment needed. The page says gonorrhea and chlamydia results take 7 to 10 days through the state lab. Hours listed there are Monday 8:30 to 4:00, Tuesday 12:00 to 8:00, Wednesday and Thursday 8:30 to 4:00, Friday 9:00 to 1:00 and Saturday 11:00 to 3:00. It is closed Sunday.

Kind Clinic

Kind Clinic has a San Antonio location at 730 Isom Road, San Antonio, TX 78216. Its website says doxyPEP is available to Kind Clinic patients only. It also offers walk-in HIV and STI testing, STI treatment, PrEP and PEP. Its blog post about the San Antonio opening describes free walk-in testing. The locations page lists a general support line, 833-937-5463, and says walk-in testing hours differ from clinic hours, so call before you go.

Other places that list testing

These organizations list STI testing, but the pages reviewed do not mention doxy-PEP. Ask them directly:

Metro Health STI Walk-In Clinic, 512 E. Highland, Suite 150, 210-207-8830. Metro Health says the clinic provides STI and HIV testing and treatment, charges a $15 office visit administrative fee, with other fees varying by service, and requires a photo ID. It does not offer anonymous testing.
Alamo Area Resource Center, 303 N. Frio, (210) 625-7200. It lists free HIV, hepatitis C, syphilis, gonorrhea and chlamydia testing, and PrEP and PEP.
BEAT AIDS, 210.212.2266. It lists free, confidential HIV and STI testing and PrEP. Call to confirm which location does testing.
CommuniCare at 6511 W Loop 1604 N, Ste. 105, (726) 224-3438. It uses a sliding fee scale for self-pay patients under 200 percent of the federal poverty guidelines.

For a fuller look at where to test, see our guide to STD testing in San Antonio.

How to get a prescription

Doxy-PEP requires a prescription. Here are the usual steps:

Choose a clinic. A primary care office, a sexual health clinic or a community organization that lists doxy-PEP can all be a starting point.
Be ready to talk about your sexual health. Clinicians ask these questions to support you, not to judge. Share any past STI diagnoses, your medicines and any allergies.
Expect testing. A clinician may offer tests for syphilis, chlamydia, gonorrhea and HIV before prescribing, and then on a regular schedule. The CDC advises screening every 3 to 6 months for people using doxy-PEP.
Ask about follow-up. Your clinician can explain how to reach them if you have side effects or questions.

The medicine should come from a licensed pharmacy with a clinician's prescription. Sourcing it any other way means no one has checked that it is the right product or the right fit for you.

Quality indicators when choosing where to go

Since this is health care and not a product you shop for, the quality markers are about the clinic and the process:

The clinician asks about your history and current medicines.
Testing is offered before and during use.
The plan matches CDC guidance, including the 72-hour window and the limits of what it prevents.
The prescription goes to a licensed pharmacy.
You get clear answers about cost and follow-up.

Cost varies. Some of the organizations above publish testing as free, but the pages reviewed do not publish a price for doxy-PEP visits or prescriptions. Ask the clinic what you would owe and whether a sliding scale or assistance applies.

Texas rules that matter

Privacy and minors

Under Texas Family Code Section 32.003, a minor of any age may consent to diagnosis and treatment of a reportable infectious disease, which covers reportable STIs and HIV. Parent or guardian consent is not required for that care. The same law lets a physician tell a parent or guardian about the treatment, with or without the minor's consent, so a provider cannot promise a parent will never be told. Ask about privacy before your visit.

Reporting

The Texas DSHS notifiable conditions list for 2026 includes chlamydia, gonorrhea, syphilis and HIV. Labs and clinicians report these infections to public health. That is a routine part of how health departments track trends.

Pregnancy

Texas Health and Safety Code Section 81.090 calls for syphilis testing at the first prenatal visit, again in the third trimester and at delivery. Since doxycycline is generally avoided in pregnancy, anyone who is pregnant or planning pregnancy should talk with their prenatal clinician about the options.

Next steps

If you are thinking about doxy-PEP, a good first step is a conversation with a clinician and an up-to-date set of tests. The CDC's GetTested locator can help you find testing sites by ZIP code.

Texas also offers free mailed at-home test kits for HIV, syphilis, gonorrhea and chlamydia for anyone in Texas aged 13 or older through the DSHS program Test for Texas. DSHS says results arrive in a secure portal seven business days after the sample reaches the lab. Testing is a useful step whether or not you end up using doxy-PEP.

Doxy-PEP in San Antonio: Who It Is For and How to Get It