Syphilis

What is syphilis?

Syphilis is a sexually transmitted infection (STI) caused by a bacterium called Treponema pallidum. It is spread mainly through direct contact with a syphilis sore during vaginal, anal, or oral sex. It can also pass from a pregnant woman to her unborn baby, which is called congenital syphilis (an infection present at birth).

Syphilis is often described as a "staged" infection because it tends to move through distinct phases over months or years if it is not treated. Early on, the signs can be mild or easy to miss. In later stages, the bacteria can damage the heart, brain, nerves, eyes, and other organs. The good news is that syphilis is curable with antibiotics, and treatment is most straightforward when the infection is found early.

Syphilis can affect anyone who is sexually active, regardless of age, gender, or sexual orientation. In many countries, reported cases have risen in recent years, which is one reason health authorities encourage regular testing for people at risk. In a hospital setting, syphilis is usually managed by specialists in infectious diseases, sometimes together with dermatologists (skin doctors), neurologists (nerve and brain doctors), or obstetricians (pregnancy doctors), depending on the stage and the organs involved.

Syphilis symptoms

Syphilis symptoms change depending on the stage of infection. Some people have no noticeable symptoms for long periods, which is why the infection can go undetected and be passed to others. The stages below describe the typical pattern, but not everyone follows it exactly.

Primary syphilis

The first sign is usually a single sore called a chancre (pronounced "shanker"). It appears at the place where the bacteria entered the body, often on the genitals, anus, rectum, lips, or inside the mouth. Key features include:

• A firm, round sore that is usually painless
• Appears several weeks after exposure
• May be hidden inside the vagina, rectum, or mouth and go unnoticed
• Heals on its own within a few weeks, even without treatment
• Swollen lymph nodes (small glands that fight infection) near the sore

Because the chancre does not hurt and disappears on its own, many people do not realize they have been infected. The infection remains in the body even after the sore heals.

Secondary syphilis

If untreated, the infection spreads through the bloodstream and can cause symptoms weeks to months later. These may include:

• A skin rash that often does not itch, frequently on the palms of the hands and soles of the feet, but it can appear anywhere on the body
• Sores in the mouth, vagina, or anus (sometimes called mucous patches)
• Raised, wart-like growths in moist areas such as the groin
• Fever, sore throat, and tiredness
• Swollen lymph nodes in several parts of the body
• Patchy hair loss
• Headaches and muscle aches

These symptoms can be mistaken for other illnesses. They also tend to fade on their own, but the infection is still present.

Latent syphilis

In the latent stage, there are no visible symptoms, but blood tests remain positive. This hidden phase can last for years. Doctors often divide it into early latent (infection acquired within roughly the past year) and late latent (infection acquired longer ago or of unknown duration), because this affects how much treatment is needed.

Tertiary (late) syphilis

A portion of people who never receive treatment develop serious complications many years after the original infection. Tertiary syphilis can involve:

• The heart and blood vessels, including damage to the main artery (aorta)
• The brain and nerves, leading to memory problems, personality changes, difficulty walking, or paralysis
• Soft, rubbery growths called gummas on the skin, bones, or internal organs

Neurosyphilis, ocular syphilis, and otosyphilis

Syphilis can affect the nervous system (neurosyphilis), the eyes (ocular syphilis), or the ears (otosyphilis) at any stage, not only in the late phase. Warning signs include severe headache, stiff neck, confusion, changes in vision, eye pain or redness, hearing loss, ringing in the ears, or dizziness. These need prompt medical attention.

Congenital syphilis

A baby infected before birth may be born early, have a low birth weight, or show signs such as a rash, jaundice (yellowing of the skin), enlarged liver or spleen, bone changes, or a persistent runny nose. Some babies have no symptoms at birth but develop problems later, including hearing loss, dental changes, or developmental delay. Untreated syphilis in pregnancy can also lead to miscarriage or stillbirth.

Causes and risk factors

The only cause of syphilis is infection with the bacterium Treponema pallidum. Understanding syphilis causes and how the bacteria spread helps explain who is most at risk.

How syphilis spreads

• Sexual contact: direct contact with a chancre or other infectious sore during vaginal, anal, or oral sex. Condoms lower the risk but do not remove it entirely, because sores can be located on areas a condom does not cover.
• Pregnancy and birth: the bacteria can cross the placenta to the unborn baby, or infect the baby during delivery.
• Rarely, blood exposure: transmission through shared needles or blood transfusion is uncommon today because donated blood is screened.

Syphilis is not spread through casual contact such as shaking hands, hugging, sharing food or utensils, toilet seats, swimming pools, or clothing.

Risk factors

Anyone who is sexually active can get syphilis, but certain factors increase the chance of exposure:

• Having sex without a condom, particularly with new or multiple partners
• Having a sexual partner who has been diagnosed with syphilis
• Living with HIV, which is often associated with a higher risk of syphilis and can change how the infection behaves
• Men who have sex with men, who account for a large share of reported cases in many regions
• Having had another sexually transmitted infection, which may indicate ongoing exposure risk
• Using drugs or alcohol in ways that lead to unprotected sex
• Exchanging sex for money or drugs
• For babies: a mother with untreated or inadequately treated syphilis during pregnancy

Having syphilis sores can also make it easier to acquire or transmit HIV, so doctors usually recommend testing for both infections at the same time.

Syphilis diagnosis

Syphilis cannot be reliably diagnosed from symptoms alone because its signs overlap with many other conditions. Syphilis diagnosis relies mainly on laboratory tests, combined with a medical history and physical examination.

Blood tests

Blood tests (also called serologic tests) look for antibodies, which are proteins the immune system produces in response to the bacteria. Two types are generally used together:

• Nontreponemal tests (such as RPR or VDRL): these are common screening tests. They also produce a number called a titer that helps doctors judge how active the infection is and whether treatment is working. They can occasionally give false-positive results in people with other conditions, so a positive result is usually confirmed with a second test.
• Treponemal tests (such as FTA-ABS, TP-PA, or automated immunoassays): these detect antibodies specific to Treponema pallidum. They typically stay positive for life, even after successful treatment, so they cannot tell a past infection from a current one on their own.

Doctors interpret the two test types together. In early primary syphilis, antibodies may not yet have developed, so a doctor may repeat testing after a few weeks if the first result is negative but suspicion remains.

Direct detection from a sore

If a chancre or other moist sore is present, a sample of fluid can sometimes be examined under a special microscope (dark-field microscopy) or tested with molecular methods (PCR, which detects the bacteria’s genetic material) to identify the bacteria directly. Availability of these tests varies between laboratories.

Testing for neurosyphilis and eye or ear involvement

If a doctor suspects the nervous system is involved, a lumbar puncture (spinal tap) may be recommended. This procedure collects a small amount of the fluid that surrounds the brain and spinal cord so it can be tested for signs of infection. People with eye or ear symptoms are usually referred for a specialist eye or hearing examination. Imaging such as MRI or CT scans is not used to diagnose syphilis itself but may be ordered to look for complications in the brain, blood vessels, or bones.

Additional testing

Because syphilis often occurs alongside other infections, doctors commonly offer testing for HIV, gonorrhea, chlamydia, and hepatitis at the same time. Pregnant women are routinely screened for syphilis at the first prenatal visit, and in some situations again later in pregnancy and at delivery.

Syphilis treatment options

Syphilis treatment is highly effective when given correctly. The mainstay is antibiotic medication; there is no role for surgery in treating the infection itself, although procedures may occasionally be needed to manage late complications.

Penicillin

Penicillin given by injection is the preferred treatment for all stages of syphilis. The number of injections depends on the stage:

• Primary, secondary, or early latent syphilis: usually a single injection of long-acting penicillin into a muscle.
• Late latent syphilis, latent syphilis of unknown duration, or tertiary syphilis without nervous system involvement: usually a series of weekly injections over several weeks.
• Neurosyphilis, ocular syphilis, or otosyphilis: usually penicillin given intravenously (into a vein) or by frequent injections over a period of about two weeks, often requiring a hospital stay or close outpatient monitoring.
• Syphilis in pregnancy: penicillin is the only recommended treatment, because it also treats the unborn baby. Women who are allergic to penicillin are usually desensitized (a supervised process that allows penicillin to be given safely) rather than switched to another drug.

Alternatives for people allergic to penicillin

For non-pregnant adults with a confirmed penicillin allergy, doctors may prescribe other antibiotics such as doxycycline or, in some circumstances, ceftriaxone. These alternatives require careful follow-up because evidence for their effectiveness is more limited than for penicillin. Your doctor will decide based on the stage of infection and your medical history.

What to expect after treatment

• Jarisch-Herxheimer reaction: some people develop fever, chills, headache, and muscle aches within the first day after treatment. This is a reaction to the bacteria dying, not an allergy, and it usually settles within 24 hours. Rest and simple fever medicine are often enough, but you should report severe symptoms.
• Abstaining from sex: you will usually be advised to avoid sexual contact until any sores have fully healed and treatment is complete, to prevent passing the infection to others.
• Partner notification and treatment: recent sexual partners need to be informed, tested, and often treated even if their tests are negative, because they may be in the early window before antibodies appear.
• Follow-up blood tests: doctors repeat nontreponemal tests at intervals (commonly around 6 and 12 months, and longer for some people) to confirm the titer is falling as expected. A rising or unchanged titer may indicate treatment failure or reinfection.

Managing late complications

Antibiotics stop the infection but cannot reverse damage that has already occurred. People with heart, blood vessel, nerve, eye, or hearing damage from late syphilis may need ongoing care from cardiologists, neurologists, ophthalmologists, or audiologists, and in some cases rehabilitation services. Aortic damage may occasionally require surgical repair. At Acibadem, syphilis and its complications are managed through the Infectious Diseases Department in coordination with other specialties as needed.

Living with syphilis and outlook

For most people diagnosed in the early stages, the outlook is very good. A complete course of antibiotics cures the infection, and early symptoms such as the chancre and rash resolve. Blood test titers usually fall over the following months, although treponemal tests often stay positive for life. This does not mean the infection is still active; it simply reflects a past infection, and it is helpful to keep a record of your treatment so future doctors can interpret results correctly.

Having had syphilis once does not protect you from getting it again. Reinfection is common in people who continue to be exposed, so ongoing prevention and periodic testing are important. Many doctors recommend regular STI screening for people with new or multiple partners, and more frequent testing for people living with HIV or taking HIV prevention medication.

The outlook is less predictable when syphilis is diagnosed late. Treatment still stops the disease from progressing, but damage to the heart, brain, nerves, eyes, or hearing may be permanent, and recovery varies from person to person. Some people improve considerably after treatment, while others are left with lasting effects that need long-term management.

A diagnosis of any sexually transmitted infection can bring feelings of worry, embarrassment, or concern about relationships. These reactions are common. Talking openly with your healthcare team, and where helpful with a counselor, can make the process of notifying partners and completing follow-up easier. Health services treat STI information confidentially.

For babies born with congenital syphilis, early treatment significantly improves outcomes, and many children who are treated promptly develop normally. Some, however, may have lasting hearing, vision, dental, or developmental problems that require follow-up through childhood. Screening and treating pregnant women is the most effective way to prevent congenital syphilis.

Frequently asked questions

What are the first syphilis symptoms?

The first sign is usually a single, firm, painless sore (chancre) at the site where the bacteria entered the body, appearing a few weeks after exposure. It may be on the genitals, anus, or in the mouth, and it can easily go unnoticed. The sore heals on its own within a few weeks, but the infection remains unless it is treated.

How is syphilis diagnosed if I have no symptoms?

Syphilis diagnosis in people without symptoms relies on blood tests that detect antibodies to the bacteria. A screening test is usually followed by a confirmatory test of a different type. If you have had a recent exposure and the first test is negative, your doctor may suggest repeating it after a few weeks, because antibodies take time to develop.

What is the standard syphilis treatment?

The standard syphilis treatment is penicillin given by injection. Early infections are often treated with a single injection, while late or long-standing infections generally need a series of weekly injections. Infections affecting the brain, eyes, or ears usually require intravenous penicillin over about two weeks. People with penicillin allergy may be offered alternative antibiotics, except in pregnancy.

Can syphilis be cured completely?

Yes, the infection can be cured with appropriate antibiotics at any stage. However, treatment cannot undo damage that has already happened to organs in late-stage disease. Also, some blood tests may remain positive for life after successful treatment, which reflects past infection rather than ongoing disease.

What causes syphilis, and can I get it from a toilet seat?

Syphilis causes come down to one bacterium, Treponema pallidum, which is passed through direct contact with an infectious sore during sex, or from a mother to her baby during pregnancy. It is not spread by toilet seats, doorknobs, swimming pools, shared clothing, or casual physical contact, because the bacteria do not survive long outside the body.

How long after treatment can I have sex again?

Doctors generally advise waiting until your treatment is finished and any sores have completely healed, and until your partners have also been tested and treated if needed. Your doctor may give more specific guidance based on the stage of your infection and your follow-up test results.

Does syphilis go away on its own?

The visible symptoms of early syphilis do go away without treatment, but the infection itself does not. The bacteria remain in the body and can cause serious complications years later. Only antibiotic treatment clears the infection, which is why testing and treatment are important even after symptoms disappear.

When to see a doctor

You should arrange a medical assessment if you notice a sore on your genitals, anus, or mouth, develop an unexplained rash (especially on the palms or soles), or learn that a sexual partner has been diagnosed with syphilis or another STI. Testing is also advisable if you have had unprotected sex with a new partner, even without symptoms. Pregnant women should make sure syphilis screening is part of their prenatal care.

Seek urgent medical attention if you have a known or suspected syphilis infection and develop any of the following red-flag signs:

• Sudden changes in vision, eye pain, or redness in one or both eyes
• New hearing loss, ringing in the ears, or severe dizziness
• Severe headache with a stiff neck, fever, or sensitivity to light
• Confusion, memory loss, personality changes, or seizures
• Weakness, numbness, difficulty walking, or loss of bladder or bowel control
• Chest pain, shortness of breath, or fainting
• A high fever or a severe reaction within a day of receiving treatment
• Signs of a serious allergic reaction to medication, such as swelling of the face or throat, difficulty breathing, or widespread hives

Prompt evaluation allows doctors to confirm the syphilis diagnosis, choose the right treatment, and reduce the risk of long-term complications.