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.

Syphilis is a bacterial infection that has been known for centuries. It is also one of the most treatable infections in sexual health care. The Centers for Disease Control and Prevention (CDC) says syphilis can be cured with treatment from a clinician. The harder part is noticing it, because the early signs can be small, painless or easy to mistake for something else.

This guide explains how syphilis behaves, what each stage can look like, how the blood tests work and what treatment and follow-up involve. It also covers what the numbers look like in Pima County and Arizona, and where people in Tucson can get tested for free or at low cost.

The short version

Syphilis is caused by a bacterium called Treponema pallidum. It spreads mainly through direct contact with a syphilis sore during vaginal, anal or oral sex, and it can pass from a pregnant person to a baby.
It moves through stages. The first sign can be a painless sore, and a later sign can be a rash. Some stages have no symptoms at all.
Diagnosis uses blood tests, and often two different kinds of them.
So, is syphilis curable? Yes. The CDC STI Treatment Guidelines (2021) say penicillin, prescribed by a clinician, is the preferred treatment at every stage.
Treatment stops the infection. It cannot reverse damage that already happened, which is why finding it early matters.

The organism: what researchers know about Treponema pallidum

The body of this guide leaves out chemistry in the usual sense, because syphilis is an infection, not a substance. The science that matters is the biology of the bacterium and the way tests and medicines act on it.

T. pallidum is a spiral-shaped bacterium called a spirochete. Research describes it as thin, fragile outside the body and unable to survive long on surfaces. That is one reason the CDC describes syphilis as spreading through direct contact with a sore, not through toilet seats, doorknobs or shared dishes.

Two features help explain why syphilis behaves the way it does:

It is hard to see for the immune system. Researchers have observed that the bacterium's outer surface carries few exposed proteins. That may help it avoid early immune detection and help explain why it can persist for years without symptoms.
It spreads through the body. The bacterium can travel through the bloodstream, which is why syphilis can eventually involve the skin, the nervous system, the eyes, the ears, the heart and other organs.

Penicillin works by interfering with the building of bacterial cell walls. Research suggests T. pallidum has stayed sensitive to penicillin for decades, which is why the CDC still recommends it as the preferred treatment.

How syphilis moves through stages

The CDC describes four stages. Not everyone has noticeable signs at each one, and the stages can overlap.

Primary stage

The CDC says the first sign is usually a sore called a chancre. It is typically firm, round and painless. It appears where the bacteria entered the body, which can be on the genitals, the anus, in the rectum or in the mouth.

Because it does not hurt, and because it can sit inside the vagina, rectum or mouth, many people never notice it. Without treatment the sore heals on its own, usually within a few weeks. Healing does not mean the infection is gone.

Secondary stage: the syphilis rash

This is the stage most people think of when they search for syphilis symptoms. The CDC says the secondary stage often brings a skin rash. The rash can show up as the first sore is healing or weeks after it has healed.

The CDC describes the syphilis rash as often made up of rough, reddish or reddish-brown spots. It can appear on the palms of the hands and the soles of the feet, but it can also appear on other parts of the body. It usually does not itch. It can also be so faint that it goes unnoticed.

Other secondary-stage signs the CDC lists include:

Fever
Swollen lymph glands
Sore throat
Patchy hair loss
Headaches and muscle aches
Tiredness
Weight loss
Wart-like or moist patches in the mouth or in warm skin folds

A rash alone cannot tell anyone whether they have syphilis. Many other conditions cause rashes, and syphilis can imitate several of them. Only a clinician and a blood test can sort that out. The rash is also fully treatable, and it fades with treatment.

Latent stage

The CDC says that if the infection is not treated, it moves into a latent stage in which there are no signs or symptoms. A person can feel completely well. The bacteria are still in the body, and a blood test can still pick the infection up. This is a major reason routine screening exists.

Tertiary stage

The CDC says that in a minority of untreated cases, syphilis can progress to a late stage years or decades later. It can affect the heart, blood vessels, brain and nervous system and other organs. This stage is serious, but it is also uncommon in places with good access to testing and treatment, which is the point of testing early.

Infection of the nervous system, eyes and ears

The CDC notes that syphilis can reach the nervous system (neurosyphilis), the eyes (ocular syphilis) or the ears (otosyphilis) at any stage. Headache, vision changes, hearing changes or dizziness in someone who may have been exposed are good reasons to speak with a clinician promptly. These problems are treatable, and clinicians decide the right care.

Why the national rise matters

The CDC's national surveillance reports show that syphilis has been climbing for more than a decade. The CDC's 2022 STI surveillance report said total syphilis cases rose about 80 percent between 2018 and 2022. The same reports describe a rise in babies born with syphilis, called congenital syphilis.

A rise matters for two practical reasons. First, the more infections there are in a community, the more likely any one person is to meet one, whatever their age, gender or orientation. Second, a rise in congenital syphilis tells public health workers that many infections are being missed during pregnancy, when testing and treatment can protect a baby.

None of this is a reason for fear. It is a reason for ordinary, routine testing, the way people check blood pressure or cholesterol.

Syphilis in Tucson and Arizona: what the data show

The Pima County Health Department's STI page states that syphilis is on the rise in Pima County. The numbers below come from the county's own published health indicator, which uses data from the CDC's National Center for HIV, Viral Hepatitis, STD and TB Prevention (NCHHSTP).

Primary and secondary syphilis, 2023: Pima County reported 26.1 cases per 100,000 people. Arizona's rate was 24.1 per 100,000 (Pima County Health Indicator: Sexually transmitted infections).
Congenital syphilis: AZPM News reported 53 confirmed cases in Pima County in 2024. Early county data it cited, which is provisional, pointed to about 24 in 2025. AZPM's reporting also described a roughly 500 percent increase in syphilis cases in Pima County from 2010 to 2024.
Congenital syphilis, statewide: CDC's 2023 table of congenital syphilis by state lists Arizona with 233 cases, a rate of 296.6 per 100,000 live births, ranking fourth among states.

These figures come from different years and different sources, so they are best read as a general picture, not a precise trend line. The county did not publish a 2024 rate for primary and secondary syphilis that this guide could verify.

Pregnancy and Arizona law

Arizona law addresses syphilis in pregnancy directly. Under A.R.S. 36-693, a physician tests a pregnant woman's blood for syphilis at the first prenatal examination after pregnancy is diagnosed. If no test was done before delivery, cord blood is taken at delivery. The statute says the state laboratory performs the test without charge.

The USPSTF recommends syphilis screening for all pregnant people. The CDC guidelines also describe extra screening later in pregnancy for people at higher risk or in areas with high rates of syphilis. Arizona's statute as published does not set a third-trimester requirement that this guide could verify, so anyone who is pregnant can ask their prenatal clinician what timing they follow.

How syphilis testing works

Syphilis is usually found with a blood test. If there is an open sore, a clinician may also take a sample from it, but most diagnoses rest on blood work. The CDC STI Treatment Guidelines (2021) describe two families of blood tests, and clinicians often use both.

Non-treponemal tests

These tests, such as the RPR and the VDRL, look for substances the body makes in response to cell damage caused by the infection, not for the bacterium itself. They report a number called a titer, such as 1:8 or 1:32.

The titer is useful for tracking. After treatment, a clinician expects the number to fall over time. Research suggests that the number can also rise with a new infection, which is how follow-up tests help show whether treatment worked. These tests can also react to other conditions, which is why a second kind of test is used to confirm.

Treponemal tests

These tests, such as the TP-PA, the FTA-ABS and several enzyme or chemiluminescence immunoassays, look for antibodies aimed specifically at T. pallidum. They are more specific. The CDC notes that they usually stay positive for life, even after successful treatment. That is not a sign of treatment failure. It is why they are not used to track recovery.

Two orders, one purpose

Some laboratories start with the non-treponemal test and confirm with a treponemal one. Others do it in reverse. The CDC guidelines describe both. A clinician will interpret the combination, and sometimes a third test is added when the first two disagree. A person does not need to decode the results alone.

Timing and early infection

Antibodies take time to develop, so a very early infection may not show up on a test yet. The CDC guidelines do not give one window that fits every person and every test. A clinician or testing counselor can tell someone whether and when a repeat test makes sense after a recent exposure.

Who is asked to test

The USPSTF recommends screening for people at increased risk of syphilis, and for all pregnant people. The CDC guidelines recommend at least yearly screening for sexually active gay, bisexual and other men who have sex with men, with more frequent screening for some, and screening for people with HIV. A clinician can say how often is right for any individual. Testing is a normal part of care, and it is for people of every gender and orientation.

Treatment: is syphilis curable?

Yes. The CDC says syphilis can be cured with the right antibiotic prescribed by a clinician. Penicillin is the preferred medicine at every stage in the CDC STI Treatment Guidelines (2021). What form of penicillin, how it is given and for how long depends on the stage and on the person's situation, so a clinician decides it.

Some points matter for anyone thinking about syphilis treatment:

Treatment is prescribed, not picked. Medicine borrowed from a friend or left over from another illness is not a safe stand-in, and it can hide signs without clearing the infection.
Treatment stops the infection, not past damage. The CDC says treatment will kill the bacterium and prevent further harm, but it may not repair damage that has already occurred.
It does not protect against another infection. A person can get syphilis again. Past syphilis does not make someone immune.
Partners matter. The CDC recommends that recent sexual partners be tested and, in many cases, treated, so the infection does not pass back and forth. A clinic or the health department can help with notifying partners.

Safety profile and who needs a different plan

Penicillin has a long safety record. Like any medicine, it has some risks. The main points the CDC guidelines raise are:

Penicillin allergy. Many people who believe they are allergic are not, and allergy testing can sort that out. Clinicians weigh alternatives for those with a confirmed allergy. The CDC guidelines say pregnant people with a penicillin allergy should be referred for desensitization, because penicillin is the only treatment recommended to protect a baby.
A short-term reaction after the first treatment. The CDC describes the Jarisch-Herxheimer reaction, which can bring fever, chills, headache and muscle aches within the first day. It is a response to the bacteria breaking down, it is not an allergy, and it usually passes without lasting harm. People can ask the clinician what to expect.
Pregnancy. Penicillin is recommended in pregnancy. Treating early protects the baby, which is why the testing law above exists.
Supply. The CDC has noted periods of limited supply of the form of penicillin used for syphilis. Anyone who runs into this can ask the clinic or the health department what is available.

Follow-up blood tests

Treatment is not the end of care. The CDC guidelines recommend follow-up clinical exams and repeat non-treponemal blood tests at set intervals after treatment, to confirm the titer is falling as expected. The clinician sets the schedule based on the stage and on other factors such as pregnancy or HIV.

If the number does not fall as expected, the clinician may repeat the test, look for reinfection or consider further evaluation. Keeping these follow-up visits is the best way to confirm that treatment worked.

Where doxycycline fits

The CDC's 2024 guidance on doxycycline post-exposure prophylaxis (doxy-PEP) addresses prevention for certain groups, namely gay, bisexual and other men who have sex with men, and transgender women, who have had a bacterial STI in the past year. CDC reports research observing fewer syphilis, chlamydia and gonorrhea infections among people using it. Doxy-PEP is a prevention option that a clinician discusses and prescribes. It is not a replacement for testing and it is not the preferred treatment for an existing syphilis infection. Whether a given Tucson clinic offers it is not published in the sources used here, so ask the clinic.

Reducing the chance of syphilis

The CDC lists several ways to lower risk. None is perfect, and none carries blame.

Condoms and dental dams lower the chance of spread, but a sore in an area they do not cover can still pass the infection.
Regular testing, with partners too, lets infections be found and treated early.
Talking openly with partners about testing helps everyone.
Anyone who notices a new sore, a rash or other changes can pause sexual contact and speak with a clinician.

Judging the quality of a testing source

The usual "sourcing" question for an ingredient has a different answer here: where to go and how to tell a reliable source. Good signs include:

It is a licensed clinic or public health program. Health departments, community health centers and established nonprofit clinics employ clinicians who can prescribe treatment on the spot or arrange it.
It uses laboratory blood tests and explains them. A good clinic will tell you which type of test it is doing, and when to expect results.
It has a plan for treatment and follow-up. A positive result should lead to care, not a dead end.
It is open about cost and privacy. Reliable programs will say what they charge, or tell you to call and ask.
It does not promise too much. No test is perfect, and an honest source says that very early infections can be missed.

The CDC's own locator, gettested.cdc.gov, lists testing sites by ZIP code and is a good way to check what is available.

Free and low-cost syphilis testing in Tucson

Several Tucson organizations offer testing. Hours and services can change, so it is wise to call first. For a fuller comparison, see the guide to STD testing in Tucson and what it costs, or go straight to the list of local clinics.

Pima County Health Department

The county runs two clinics that list HIV and STI testing, PrEP services and navigation. Pima County says it uses a sliding fee scale based on income, that nobody is turned away for inability to pay and that minors do not need parental consent.

Theresa Lee Public Health Center, 1493 W. Commerce Court, Tucson, AZ 85746. Phone 520-724-7900. The county's Clinic Hours page lists HIV and STI testing by appointment only. The county's STI page says clients are seen on a walk-in basis, and the two pages do not agree, so calling ahead is the safest plan. The county lists no services from noon to 1 p.m. and says the clinic is closed on the first Thursday of every month.
Pima County Northwest Clinic, 1010 W. Miracle Mile, Tucson, AZ 85705. Phone 520-724-2880. The county lists HIV and STI testing here but gives no hours for it. Its Clinic Hours page says walk-in services are available as capacity allows. Call to confirm.

Details are on the county's HIV and STI page and Clinic Hours page.

Southern Arizona AIDS Foundation (SAAF Health)

SAAF is at 375 S. Euclid Avenue, Tucson, AZ 85719. Phone 520-628-7223 (toll-free 800-771-9054). The CDC GetTested listing for SAAF shows free HIV, hepatitis and STI tests, including syphilis, with appointments required. SAAF's own testing page says an appointment is the best option and mentions a Wednesday evening walk-in window from 5 to 7 p.m. That page focuses on HIV testing and does not list STI tests, so call to confirm syphilis testing and eligibility. See SAAF's testing page.

El Rio Health

El Rio Health is a community health center. The CDC GetTested listing for its Congress Street location (839 W Congress St, Tucson, AZ 85745) shows syphilis testing, requires an appointment and lists a sliding scale. The Southeast Campus (6950 E Golf Links Rd, Tucson, AZ 85730) is listed for syphilis testing as well, with no published fees. Both use 520-670-3909. The CDC listing says to contact the organization about eligibility and hours.

Planned Parenthood Southern Arizona

The Regional Health Center is at 2255 N Wyatt Dr, Tucson, AZ 85712. The 211 Arizona listing gives 520-408-7526, says walk-ins are accepted and says fees vary. Other directories show a different phone number and hours, so confirm by phone.

University of Arizona students

UA Campus Health Service offers Express STI testing for students only, with a published flat fee of $65. The page describes gonorrhea and chlamydia testing for people without symptoms and says to call to schedule if symptoms are present. It does not mention syphilis testing, so students can call 520-621-9202 and ask. Details are on the Campus Health page.

Minors and privacy

Under A.R.S. 44-132.01, a minor who may have a venereal disease can consent to medical care for diagnosis or treatment, and a parent's consent is not required. The Pima County Health Department also says minors do not need parental consent at its clinics. Laboratories and clinicians report certain infections, including syphilis, to the health department under Arizona's communicable disease reporting law, A.R.S. 36-621. That is a public health function and part of how outbreaks are tracked.

A calm next step

Syphilis is common enough in Pima County that testing belongs in routine care, and curable enough that finding it early has a simple payoff. Anyone with a new sore, an unexplained rash, a recent partner who tested positive or a pregnancy can call one of the clinics above. A clinician can explain which tests make sense and what comes next.

Syphilis in Tucson: Symptoms, Testing and Treatment