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 is easy to miss and straightforward to treat. Many people never notice the first sign. Others see a rash and do not connect it to anything sexual. A blood test can find it, and a clinician can treat it.

This guide explains how syphilis behaves in the body, what the stages look like, how testing works, and what treatment and follow-up involve. It also covers what the Southern Nevada Health District and the Nevada Division of Public and Behavioral Health report for Clark County, and where to get tested in Las Vegas for free or at low cost.

It is written for everyone, whatever your gender, orientation or relationship status. Syphilis is a common infection, and getting tested is a routine health step.

The short answer: is syphilis curable?

Yes. The CDC STI Treatment Guidelines (2021) list penicillin as the preferred treatment for syphilis at every stage. Syphilis is curable with treatment from a clinician. The clinician chooses the exact medicine, the number of injections and the timing based on how long the infection has been present and where it has spread.

Treatment stops the infection and prevents further damage. It cannot reverse damage that has already happened, which is one reason earlier testing matters. Nothing you can buy over the counter treats syphilis, and it does not go away on its own. The signs can fade while the bacteria stay in the body.

What the bacterium is, and why that shapes testing

Syphilis is caused by a spiral-shaped bacterium called Treponema pallidum. The CDC explains that it spreads through direct contact with a syphilis sore during vaginal, anal or oral sex. It can also pass from a pregnant person to a baby.

This organism is hard to grow in a standard laboratory dish. That is a big reason diagnosis relies mostly on blood tests that detect the body's response to the bacterium, rather than on growing it from a sample. In some cases, a clinician may also look at fluid from a sore under a specialized microscope.

Research suggests the bacterium moves into the bloodstream early. That helps explain why symptoms can show up in many parts of the body, and why the rash is not limited to the genital area.

The stages of syphilis

The CDC describes syphilis in stages. The stages do not always follow a tidy order, and some people have no noticeable signs at any stage. Only a test can tell what is going on.

Primary stage: a sore

The CDC describes the first sign as a sore, called a chancre. It is usually firm, round and painless. It appears where the bacteria entered the body, such as the genitals, anus, rectum or mouth.

Because it does not hurt, it is easy to overlook. A sore inside the vagina, rectum or mouth may not be seen at all. The CDC says the sore usually heals by itself within a few weeks, even without treatment. Healing does not mean the infection is gone.

Secondary stage: syphilis symptoms beyond the sore

Secondary syphilis can appear while a first sore is healing or after it has healed. This is when many people first notice something is different.

The CDC lists these common syphilis symptoms in the secondary stage:

A skin rash on one or many parts of the body
Fever and swollen lymph glands
Sore throat
Patchy hair loss
Headaches and muscle aches
Weight loss and tiredness
Moist, wart-like patches in warm areas of the body, or sores in the mouth

These signs also happen with many other conditions, including common viral illnesses and skin problems. That is exactly why symptoms alone cannot settle the question.

What the syphilis rash can look like

The syphilis rash gets its own section because it is the sign people most often misread. The CDC describes it as rough, reddish-brown spots that can show up on the palms of the hands and the soles of the feet. It can also appear on the chest, back or elsewhere, and it may be faint.

The CDC notes that the rash usually does not itch. That can make it easy to ignore. It also fades on its own, even without treatment, so a rash that goes away does not mean the infection has gone.

If you notice a rash like this, especially along with a recent new partner or a past sore, ask a clinician about a syphilis blood test. A clinician can examine the skin and decide which tests make sense. Many other conditions cause rashes on the palms and soles, so a clinician's exam is the way to sort it out.

Latent stage: no signs

After the secondary stage, syphilis can enter a latent stage with no signs or symptoms. A person can be in this stage for years. Blood tests are the only way to find it. The CDC divides latent syphilis into early and late categories, which helps the clinician pick treatment.

Tertiary stage: later complications

The CDC explains that untreated syphilis can, in some people, progress to a late stage many years later. At that stage it can affect the heart, blood vessels, brain and nervous system, and other organs. Not everyone with untreated syphilis reaches this point. It is one more reason health agencies encourage testing for people at increased risk.

Infection of the eyes, ears or nervous system

The CDC also describes ocular syphilis, otic syphilis and neurosyphilis. These can occur at any stage. Changes in vision, hearing loss, ringing in the ears, severe headache or changes in thinking are reasons to be seen promptly by a clinician. These signs have many possible causes, and a clinician can evaluate them.

Why the national rise matters

The CDC's national surveillance reports show that syphilis cases have risen across the United States over the past decade. This includes congenital syphilis, which is syphilis passed to a baby during pregnancy. Syphilis was once much less common, and many clinicians and patients are less familiar with it than they are with chlamydia.

That matters for two reasons. First, with more infections in the community, the chance that a given partner has it goes up, even for people who feel they are at low risk. Second, because the signs are subtle, many infections are found only when someone is tested for something else.

Rising rates are a reason for routine testing, not a reason for alarm. The infection is treatable at every stage.

Syphilis in Las Vegas and Nevada: what the data show

Las Vegas is in Clark County, which the Southern Nevada Health District serves. The health district reports that it serves more than 2.3 million residents.

The Nevada Division of Public and Behavioral Health, Office of State Epidemiology, published these figures in its Nevada 2023 STD Fast Facts:

Clark County had 554 cases of primary and secondary syphilis in 2023, a rate of 23.2 per 100,000 people.
Nevada overall had 725 cases of primary and secondary syphilis, a rate of 22.2 per 100,000 people.

Primary and secondary syphilis are the earliest, most infectious stages. These counts do not include every stage, so they do not capture everyone living with syphilis.

The Southern Nevada Health District also publishes provisional quarterly disease statistics. Its fourth-quarter 2025 report, with data as of February 5, 2026, lists 191 primary and secondary syphilis cases for 2025 and 363 early non-primary, non-secondary cases. For 2024, the same report lists 371 and 568. It also lists 36 congenital syphilis cases in 2024 and none so far in 2025.

These 2025 numbers are provisional and may change as reports are finalized. Lower counts could reflect fewer infections, but they could also reflect differences in testing or reporting, so they are not enough on their own to say whether syphilis is truly declining in Clark County.

Nevada law also treats syphilis as a reportable disease. Under Nevada Administrative Code chapter 441A, health care providers must report cases or suspected cases to the local health authority. This is how the numbers above are collected. It is a public-health reporting duty, and it does not make a test result public.

How syphilis is tested

Testing usually means a blood draw. The CDC STI Treatment Guidelines (2021) explain that diagnosis generally uses two kinds of blood tests, and both are needed to interpret a result.

Treponemal tests

Treponemal tests look for antibodies made specifically against the syphilis bacterium. The CDC notes that these antibodies usually stay detectable for life, even after successful treatment. A positive treponemal test, by itself, cannot tell whether an infection is current or was treated in the past.

Non-treponemal tests

Non-treponemal tests, such as the RPR and VDRL, measure a different kind of antibody that rises and falls with how active the infection is. The result is reported as a number called a titer. The CDC explains that clinicians use these tests both to help confirm a diagnosis and to track whether treatment is working.

Putting the two together

Laboratories may run these tests in either order. If the first test is positive, the second helps confirm the result and guides the next step. A single reactive test is not a final answer. A clinician interprets the pair along with your history, exam and any prior results.

Timing after exposure

Any infection test can be negative very soon after exposure, because the body takes time to make detectable antibodies. A negative result soon after a possible exposure may not tell the whole story. I am not citing a specific window period here, because the right interval depends on the test and your situation. A clinician can tell you whether and when to retest, and the CDC's guidance is the source they use.

Who should be screened

The U.S. Preventive Services Task Force recommends syphilis screening for adults and adolescents who are at increased risk, and for all pregnant people. The CDC adds that sexually active men who have sex with men, people with HIV, and people taking HIV PrEP should be screened regularly. A clinician can help you work out how often that means for you.

The CDC also recommends HIV testing for anyone who is diagnosed with syphilis, since the two infections can occur together. Many people are tested for syphilis, HIV, chlamydia and gonorrhea at the same visit. If you are weighing a full panel, see our guide to STD testing in Las Vegas, where to get tested and what it costs, and our page on chlamydia symptoms, testing and treatment in Las Vegas.

Syphilis treatment: what a clinician prescribes

For syphilis treatment, the CDC guidelines name penicillin G as the preferred medicine at every stage. A clinician decides the type, route and number of doses. Early syphilis and longer-standing syphilis are treated differently, and so is infection involving the eyes, ears or nervous system. Those details belong to your clinician, not to a web page.

Safety profile and contraindications

Penicillin has a long track record, and the CDC describes it as effective for syphilis. A few points are worth knowing before a visit:

Allergy. Tell the clinician if you have ever had a reaction to penicillin. The CDC notes that people with a reported allergy sometimes turn out not to be truly allergic, and that a clinician can assess this. Alternatives exist for some non-pregnant people. The CDC advises that pregnant people with a penicillin allergy generally need penicillin after an allergy specialist's guidance, because other options are not considered reliable for protecting the baby.
A temporary reaction. The CDC describes the Jarisch-Herxheimer reaction, which can bring fever, chills, headache and muscle aches within a day of starting treatment. It is usually short-lived, and a clinician can tell you what to expect and when to call.
Pregnancy. Treatment during pregnancy protects both the parent and the baby, which is why screening is built into prenatal care.
Do not self-treat. Leftover or borrowed antibiotics can hide symptoms without curing the infection.

Partners and avoiding re-infection

Having syphilis once does not protect you from getting it again. The CDC advises avoiding sex until treatment is completed and any sores have healed, and notes that recent partners may need testing and possibly treatment. A clinician or the Southern Nevada Health District can explain how to reach partners. You can do that yourself, or ask for help.

Follow-up blood tests

Treatment is followed by repeat blood tests. The CDC explains that clinicians track the non-treponemal titer over time. After successful treatment, the number is expected to fall, and a fourfold drop is the usual marker of a good response. Your clinician sets the follow-up schedule based on the stage and your health.

Treponemal tests, as noted above, usually stay positive for life. A person who has been treated can keep a positive treponemal result without having an active infection. It helps to keep a record of your treatment, so a future clinician can read your results correctly.

Doxy-PEP and prevention

In 2024, the CDC issued guidance on doxycycline taken after sex (doxy-PEP) to lower the chance of syphilis, chlamydia and gonorrhea. The guidance applies to men who have sex with men and transgender women who have had a bacterial STI in the past year. It is a prevention tool, and it is prescribed by a clinician. It is not a treatment for existing syphilis. The Southern Nevada Community Health Center lists doxy-PEP among its sexual health services.

Getting tested in Las Vegas

You can find the full list of local options on our Las Vegas testing clinics list. Here is what the sources say about the main ones. Hours and walk-in capacity can change, so call before you go.

Southern Nevada Health District Sexual Health Clinic

The health district runs a sexual health clinic at 280 S. Decatur Blvd., Las Vegas, NV 89107, and a second location at the Fremont Public Health Center, 2830 E. Fremont St., Las Vegas, NV 89104. The phone number is (702) 759-1700.

The health district says walk-ins for STI testing and treatment are available until capacity is reached. Charges are based on income and household size, and the health district says you will not be turned away on the day of your visit because you cannot pay. Bring photo ID and proof of income.

The health district also offers free Express Testing, a walk-in service for people who do not have symptoms. At the Decatur site, it lists Express Testing Monday through Thursday, 7:30 AM to 12 PM and 1 PM to 3:30 PM. At Fremont, it lists Fridays, 7:30 AM to 4 PM. The health district's own pages list different clinic hours in different places, so confirm hours by phone. Ask whether a syphilis blood test is part of Express Testing on the day you plan to go, because the page does not spell out every test.

If you have a sore or a rash, the regular walk-in clinic is the better fit than Express Testing, which is designed for people without symptoms. The health district also lists free Express Testing in Henderson on Tuesdays and in Mesquite on the fourth Monday of the month.

Arlene Cooper Community Health Center at The Center

This clinic, run by The LGBTQ Community Center of Southern Nevada, is at 401 S. Maryland Parkway, Las Vegas, NV 89101. Appointments are at 702-802-5432. The center says it offers free HIV testing and low-cost STI screening, bills certain insurance, and provides STI treatment on site. Appointments are highly encouraged, with a limited number of walk-in spots daily. Its page lists Monday to Friday 8:00 am to 6:00 pm and Saturday 7:30 am to 4:00 pm, though the site footer shows different hours, so confirm before you go.

Nevada Health Centers

Nevada Health Centers lists STD testing at the Martin Luther King Family Health Center, 1799 Mount Mariah Dr., Las Vegas, NV 89106, phone 702.383.1961, and the Nellis Family Medical Center, 691 N. Nellis Blvd., Las Vegas, NV 89110, phone 702.563.4662. It offers a sliding-fee discount program based on family size and income. Its pages do not say whether walk-ins are accepted, so call first.

UNLV students

The UNLV Student Health Center, at the Student Recreation and Wellness Center, 4505 S. Maryland Pkwy., lists testing for sexually transmitted infections, including HIV. It serves UNLV students. Call 702-895-3370 for details and pricing, which its page does not list.

At-home options

The health district's Collect2Protect program lists at-home HIV self-test kits and mail-in kits for gonorrhea and chlamydia. Its page does not list a syphilis kit, and it does not state current prices, so ask the program directly. The CDC's gettested.cdc.gov tool can also help you find testing sites by ZIP code.

Your rights and privacy in Nevada

Nevada Revised Statutes 129.060 allows a minor to consent to examination and treatment for any sexually transmitted disease, and to STD prevention services. The statute sets no minimum age.

For pregnancy, NRS 442.010 requires a syphilis test at the first prenatal visit and again in the third trimester, and at delivery in certain situations. This is part of routine care, and it protects babies from congenital syphilis.

How to find reliable information and a good clinic

Quality indicators matter in health information just as they do for any service. Look for these signs:

Named public sources. The CDC, the U.S. Preventive Services Task Force and the Southern Nevada Health District publish their methods and update dates.
A clinician who explains both tests. A good visit includes what each result means and what comes next.
Clear costs up front. Sliding-scale clinics should explain how fees are set. If a price is not posted, ask.
Written results and treatment records. These help you and any future clinician read your follow-up numbers.
No pressure and no judgment. Testing is routine care.

What to do next

If you have a sore, a rash or another sign you are unsure about, or if a partner has told you they were treated, contact a clinic from the list above and ask about a syphilis blood test. If you have no signs but have a new partner, a partner with other partners, or have not been tested in a while, free or low-cost testing is available locally. You can also look up sites on gettested.cdc.gov.

Syphilis is curable, and the path is simple: a blood test, treatment from a clinician if needed, and follow-up tests to confirm it worked.

Syphilis in Las Vegas: Symptoms, Testing and Treatment