Syphilis Treatment: Penicillin Shots, Doxycycline When Allergy Blocks Bicillin, and When Telehealth Is Enough

Last updated: August 16, 2026

Syphilis treatment is not an over-the-counter purchase. Treponema pallidum responds to the right antibiotic, at the right stage, for the right duration. The [CDC](https://www.cdc.gov/syphilis/about/index.html) is blunt: syphilis is curable, and treatment does not always reverse damage already done. Most adults with early disease need a single intramuscular shot of benzathine penicillin G. Some adults with a documented penicillin allergy can use oral doxycycline. Pregnancy, neurosyphilis, ocular or ear involvement, and congenital infection sit in a different lane and need in-person specialty care.

This guide covers what syphilis antibiotics actually do, why you cannot treat this with leftover pills, how telehealth can start testing and counseling, and when you still need a clinic for the injection. Klarity Health has 2,000+ licensed providers. Coverage and whether a visit is appropriate for your stage vary by plan and by clinical findings. Verify benefits before you book.

Need to talk through a possible STI, a new sore, or a positive test? A Klarity provider can review symptoms, order labs when appropriate, and discuss next steps. First-line syphilis therapy is often an in-clinic penicillin injection. Telehealth still helps with triage, partner questions, and related prescriptions. See online prescription options or browse conditions.

TLDR

• Syphilis is a curable STI. Untreated infection can move from a painless sore to rash, then silent latent disease, then organ damage years later ([CDC About Syphilis](https://www.cdc.gov/syphilis/about/index.html)).
• Preferred therapy for all stages is parenteral penicillin G. For primary and secondary syphilis in adults, CDC recommends benzathine penicillin G 2.4 million units IM in a single dose ([CDC P&S syphilis](https://www.cdc.gov/std/treatment-guidelines/p-and-s-syphilis.htm)).
• There is no reliable over-the-counter syphilis antibiotic. Azithromycin is not a substitute because of documented macrolide resistance ([CDC P&S syphilis](https://www.cdc.gov/std/treatment-guidelines/p-and-s-syphilis.htm)).
• Nonpregnant adults with penicillin allergy and early syphilis may use doxycycline 100 mg twice daily for 14 days, with close follow-up. Pregnant patients who report penicillin allergy should be desensitized and treated with penicillin ([CDC syphilis guidelines](https://www.cdc.gov/std/treatment-guidelines/syphilis.htm)).
• A telehealth visit can review symptoms, arrange testing, and counsel partners. The benzathine penicillin shot itself is intramuscular and typically requires a clinic, health department, or infusion setting.
• Medicare Part B telehealth from home continues through December 31, 2027 for many covered services ([Medicare.gov telehealth](https://www.medicare.gov/coverage/telehealth)). Commercial coverage still varies by plan.

What syphilis is, and why stage changes the plan

Syphilis is a bacterial STI. It spreads through direct contact with a sore during vaginal, anal, or oral sex. It does not spread from toilet seats, doorknobs, or shared utensils ([CDC About Syphilis](https://www.cdc.gov/syphilis/about/index.html)).

Stage drives both symptoms and the length of therapy:

• Primary: one or more usually painless sores (chancres) at the entry site. The sore lasts 3 to 6 weeks and can heal without treatment. The infection stays.
• Secondary: rash that can involve palms and soles, mucous patches, fever, swollen nodes, patchy hair loss, fatigue.
• Latent: no visible signs. Early latent (infection in the past year) still uses a shorter penicillin course. Late latent or unknown duration usually needs three weekly shots.
• Tertiary: heart, vessels, bone, or other organ damage, often 10 to 30 years later.
• Neuro, ocular, and otic syphilis: can appear at any stage. Headache, vision change, hearing loss, or confusion need urgent in-person evaluation, not a mail-order script ([CDC About Syphilis](https://www.cdc.gov/syphilis/about/index.html)).

Providers usually confirm infection with a blood test (nontreponemal plus treponemal serology). Fluid from a lesion can also be tested. You cannot diagnose syphilis from a photo of a sore alone.

First-line syphilis antibiotics: benzathine penicillin G

The [CDC STI Treatment Guidelines](https://www.cdc.gov/std/treatment-guidelines/syphilis.htm) state that penicillin G, given parenterally, is the preferred drug for every stage. The product and schedule change with duration of infection:

For primary and secondary syphilis, extra doses of benzathine penicillin, amoxicillin, or other add-on antibiotics do not improve results compared with the single recommended shot, including in people with HIV ([CDC P&S syphilis](https://www.cdc.gov/std/treatment-guidelines/p-and-s-syphilis.htm)).

Benzathine penicillin (often known by the brand Bicillin L-A) is a long-acting intramuscular injection. It is not the same as oral penicillin VK you might have leftover from a dental visit. It is not the same as IV penicillin used for neurosyphilis. Mixing those products is a common, dangerous error.

Doxycycline for syphilis and other alternatives

Search volume for syphilis antibiotics and doxycycline for syphilis is high because people want a pill. For some nonpregnant adults with a true penicillin allergy and early (primary or secondary) syphilis, CDC lists doxycycline 100 mg orally twice daily for 14 days, or tetracycline 500 mg four times daily for 14 days. Doxycycline is usually easier to finish. Ceftriaxone 1 g daily IM or IV for 10 days has supporting data, but the ideal dose and length are not fully defined ([CDC P&S syphilis](https://www.cdc.gov/std/treatment-guidelines/p-and-s-syphilis.htm)).

For late latent syphilis or syphilis of unknown duration, if penicillin cannot be used, CDC lists doxycycline 100 mg twice daily for 28 days as an alternative in nonpregnant people ([CDC latent syphilis](https://www.cdc.gov/std/treatment-guidelines/latent-syphilis.htm)).

What does not work as a casual substitute:

• Azithromycin. CDC says not to use it for syphilis because of chromosomal resistance and documented failures in multiple U.S. areas.
• Random leftover amoxicillin or “STI packs.” Stage, dose, and product matter.
• Any over-the-counter cream or “immune booster.” None of these clear T. pallidum.

If a clinician cannot confirm you will finish pills and return for titers, CDC prefers desensitization and benzathine penicillin instead of an oral alternative ([CDC P&S syphilis](https://www.cdc.gov/std/treatment-guidelines/p-and-s-syphilis.htm)).

What a telehealth visit can and cannot do

Klarity visits are useful when you need a licensed clinician to:

• Sort a new genital, anal, or oral sore from herpes, chancroid, trauma, or irritation (see also our yeast infection treatment guide if itching and discharge dominate).
• Order or interpret syphilis serology and related STI tests.
• Explain partner notification and when partners need empiric treatment.
• Discuss doxycycline only when it is clinically appropriate (nonpregnant, early disease, documented allergy or penicillin shortage protocols).
• Send you to a local clinic or health department for benzathine penicillin when that is the right drug.

Telehealth does not replace an IM or IV penicillin infusion. It does not treat neurosyphilis, eye involvement, hearing loss, or pregnancy at home. If you have a severe headache, vision change, confusion, chest pain, or you are pregnant with a positive test, go to in-person emergency or obstetric care.

For how a typical virtual visit works, see our online doctor visit guide. For pharmacy refills that are not new STI therapy, see online prescription refill.

Want a same-week clinician review? Check online doctor prescription options at Klarity Health. Providers can help you plan testing and treatment. They will not promise that every case stays fully virtual.

Follow-up titers, partners, and getting syphilis again

CDC recommends clinical and serologic checks at 6 and 12 months after treatment for primary and secondary syphilis. Compare the new nontreponemal titer with the titer on the day you were treated. A fourfold drop is the usual target. About 10% to 20% of people treated with the recommended regimen still do not hit that drop by 12 months. Age, starting titer, and prior syphilis all affect how fast numbers fall ([CDC P&S syphilis](https://www.cdc.gov/std/treatment-guidelines/p-and-s-syphilis.htm)).

Signs that you need to be seen again sooner:

• Lesions that persist or come back.
• A fourfold titer rise that lasts more than 2 weeks (reinfection or failure).
• New neurologic, eye, or ear symptoms.

Successful treatment does not create immunity. You can get syphilis again if a partner is untreated. Sores in the mouth, vagina, anus, or under the foreskin are easy to miss ([CDC About Syphilis](https://www.cdc.gov/syphilis/about/index.html)).

CDC also wants HIV testing at diagnosis. If that test is negative, PrEP counseling is appropriate, especially in areas with high HIV prevalence, with a repeat HIV test in 3 months when indicated ([CDC P&S syphilis](https://www.cdc.gov/std/treatment-guidelines/p-and-s-syphilis.htm)).

Pregnancy, babies, and why “wait and see” is unsafe

Pregnant people can pass syphilis to the fetus. Risks include preterm birth, stillbirth, and congenital infection. CDC advises syphilis testing at the first prenatal visit. Some patients need repeat testing at 28 weeks and at delivery. Infants can look well at birth and still get seriously ill within weeks if untreated ([CDC About Syphilis](https://www.cdc.gov/syphilis/about/index.html)).

Penicillin is the only regimen with documented efficacy in pregnancy. If you report a penicillin allergy, guidelines call for desensitization and penicillin, not a casual switch to doxycycline ([CDC syphilis guidelines](https://www.cdc.gov/std/treatment-guidelines/syphilis.htm)). This is obstetric and infectious-disease care, not a cash-pay telemed pill pack.

Cost, insurance, and Medicare telehealth timing

A visit, labs, and the injection often bill separately. Commercial plans may cover STI testing and treatment as preventive or as a medical visit. Copays, deductibles, and whether the injection must go through a specific clinic all vary. Use “may” language when you talk with your insurer. Confirm in-network labs and whether the health department offers low- or no-cost benzathine penicillin in your county.

Through December 31, 2027, Medicare Part B covers many telehealth services from anywhere in the U.S., including your home, after the Part B deductible, typically at 20% of the Medicare-approved amount ([Medicare.gov](https://www.medicare.gov/coverage/telehealth); [HHS telehealth policy](https://telehealth.hhs.gov/providers/telehealth-policy/telehealth-policy-updates)). That flexibility covers eligible video visits. It does not turn an IM penicillin dose into a mail-order product.

Klarity offers insurance and cash-pay options with transparent pricing. Coverage is not guaranteed. Verify benefits before you rely on a plan to pay for labs or an injection.

When to go in person the same day

• Pregnancy and a positive syphilis test, or no prenatal testing yet with known exposure.
• Eye pain, vision change, hearing loss, severe headache, stroke-like symptoms, or confusion.
• A chancre plus fever and a very ill appearance, or concern for another overlapping STI that needs intramuscular ceftriaxone.
• A child with suspected syphilis (specialist plus child-protection evaluation per CDC).
• You cannot access benzathine penicillin and you are not a candidate for a carefully supervised oral alternative.

How Klarity Health fits

Klarity’s 2,000+ licensed providers can evaluate many sexual-health questions online, order tests when appropriate, and write prescriptions that are safe to fill at a local pharmacy. For syphilis, that often means a hybrid path: virtual assessment, then a documented handoff for the CDC-preferred shot. Related care for other infections is available through online doctor prescription visits and our condition directory.

Nothing on this page is a diagnosis. Your clinician will match stage, allergy history, pregnancy status, and neurologic exam before choosing a drug.

FAQ

Is there a pill that cures syphilis?

Sometimes, for selected nonpregnant adults with early disease and penicillin allergy, doxycycline for 14 days is an accepted alternative. First-line therapy remains a benzathine penicillin injection. Azithromycin is not recommended ([CDC P&S syphilis](https://www.cdc.gov/std/treatment-guidelines/p-and-s-syphilis.htm)).

Can I buy syphilis antibiotics online without a visit?

You should not. Wrong product, wrong duration, and missed neurosyphilis or pregnancy all cause preventable harm. Use a licensed visit, then a legitimate pharmacy or clinic.

How soon am I no longer contagious?

After adequate penicillin, infectious lesions typically heal and sexual transmission risk falls. Your clinician will tell you when sex can resume and that partners need evaluation too. Do not rely on the sore disappearing as proof of cure. The primary sore can heal on its own while infection continues ([CDC About Syphilis](https://www.cdc.gov/syphilis/about/index.html)).

Do I need a spinal tap?

Not routinely for uncomplicated primary or secondary syphilis without neurologic, ocular, or otic signs. CSF testing is for people with those findings or certain treatment-failure scenarios ([CDC P&S syphilis](https://www.cdc.gov/std/treatment-guidelines/p-and-s-syphilis.htm)).

Disclaimer

This article is educational and is not medical advice. Syphilis staging and drug choice belong to a licensed clinician who has your history, exam, and labs. Insurance coverage for visits, labs, and injections varies by plan. Confirm benefits before you book. Klarity Health does not guarantee that any specific medication will be prescribed or that treatment can stay fully virtual.